lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 2 Jun 2017 17:17:31 +0530
From:   Jassi Brar <jassisinghbrar@...il.com>
To:     Ruslan Bilovol <ruslan.bilovol@...il.com>
Cc:     Felipe Balbi <balbi@...nel.org>, Daniel Mack <zonque@...il.com>,
        Clemens Ladisch <clemens@...isch.de>,
        Jonathan Corbet <corbet@....net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Chen <hzpeterchen@...il.com>,
        Julian Scheel <julian@...st.de>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        linux-doc@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/3] usb: gadget: f_uac2: split out audio core

On Tue, May 30, 2017 at 5:13 AM, Ruslan Bilovol
<ruslan.bilovol@...il.com> wrote:
> On Mon, May 22, 2017 at 6:58 PM, Jassi Brar <jassisinghbrar@...il.com> wrote:
>> On Thu, May 18, 2017 at 4:07 AM, Ruslan Bilovol
>> <ruslan.bilovol@...il.com> wrote:
>>> Abstract the peripheral side ALSA sound card code from
>>> the f_uac2 function into a component that can be called
>>> by various functions, so the various flavors can be split
>>> apart and selectively reused.
>>>
>>> Visible changes:
>>>  - add uac_params structure to pass audio paramteres for
>>>    g_audio_setup
>>>  - make ALSA sound card's name configurable
>>>  - add [in/out]_ep_maxpsize
>>>  - allocate snd_uac_chip structure during g_audio_setup
>>>  - add u_audio_[start/stop]_[capture/playback] functions
>>>
>>> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@...il.com>
>>> ---
>>>  drivers/usb/gadget/Kconfig            |   4 +
>>>  drivers/usb/gadget/function/Makefile  |   1 +
>>>  drivers/usb/gadget/function/f_uac2.c  | 721 ++++------------------------------
>>>  drivers/usb/gadget/function/u_audio.c | 661 +++++++++++++++++++++++++++++++
>>>  drivers/usb/gadget/function/u_audio.h |  95 +++++
>>>  drivers/usb/gadget/legacy/Kconfig     |   1 +
>>>  6 files changed, 846 insertions(+), 637 deletions(-)
>>>  create mode 100644 drivers/usb/gadget/function/u_audio.c
>>>  create mode 100644 drivers/usb/gadget/function/u_audio.h
>>>
>>> diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
>>> index c164d6b..2ba0ace 100644
>>> --- a/drivers/usb/gadget/Kconfig
>>> +++ b/drivers/usb/gadget/Kconfig
>>> @@ -158,6 +158,9 @@ config USB_U_SERIAL
>>>  config USB_U_ETHER
>>>         tristate
>>>
>>> +config USB_U_AUDIO
>>> +       tristate
>>> +
>>>  config USB_F_SERIAL
>>>         tristate
>>>
>>> @@ -381,6 +384,7 @@ config USB_CONFIGFS_F_UAC2
>>>         depends on SND
>>>         select USB_LIBCOMPOSITE
>>>         select SND_PCM
>>> +       select USB_U_AUDIO
>>>         select USB_F_UAC2
>>>         help
>>>           This Audio function is compatible with USB Audio Class
>>> diff --git a/drivers/usb/gadget/function/Makefile b/drivers/usb/gadget/function/Makefile
>>> index cb8c225..b29f2ae 100644
>>> --- a/drivers/usb/gadget/function/Makefile
>>> +++ b/drivers/usb/gadget/function/Makefile
>>> @@ -32,6 +32,7 @@ usb_f_mass_storage-y          := f_mass_storage.o storage_common.o
>>>  obj-$(CONFIG_USB_F_MASS_STORAGE)+= usb_f_mass_storage.o
>>>  usb_f_fs-y                     := f_fs.o
>>>  obj-$(CONFIG_USB_F_FS)         += usb_f_fs.o
>>> +obj-$(CONFIG_USB_U_AUDIO)      += u_audio.o
>>>  usb_f_uac1-y                   := f_uac1.o u_uac1.o
>>>  obj-$(CONFIG_USB_F_UAC1)       += usb_f_uac1.o
>>>  usb_f_uac2-y                   := f_uac2.o
>>> diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
>>> index d4565b5..059a14a 100644
>>> --- a/drivers/usb/gadget/function/f_uac2.c
>>> +++ b/drivers/usb/gadget/function/f_uac2.c
>>> @@ -15,10 +15,7 @@
>>>  #include <linux/usb/audio-v2.h>
>>>  #include <linux/module.h>
>>>
>>> -#include <sound/core.h>
>>> -#include <sound/pcm.h>
>>> -#include <sound/pcm_params.h>
>>> -
>>> +#include "u_audio.h"
>>>  #include "u_uac2.h"
>>>
>>>  /*
>>> @@ -50,455 +47,23 @@
>>>  #define UNFLW_CTRL     8
>>>  #define OVFLW_CTRL     10
>>>
>>> -struct uac2_req {
>>> -       struct uac2_rtd_params *pp; /* parent param */
>>> -       struct usb_request *req;
>>> -};
>>> -
>>> -struct uac2_rtd_params {
>>> -       struct snd_uac2_chip *uac2; /* parent chip */
>>> -       bool ep_enabled; /* if the ep is enabled */
>>> -       /* Size of the ring buffer */
>>> -       size_t dma_bytes;
>>> -       unsigned char *dma_area;
>>> -
>>> -       struct snd_pcm_substream *ss;
>>> -
>>> -       /* Ring buffer */
>>> -       ssize_t hw_ptr;
>>> -
>>> -       void *rbuf;
>>> -
>>> -       size_t period_size;
>>> -
>>> -       unsigned max_psize;
>>> -       struct uac2_req *ureq;
>>> -
>>> -       spinlock_t lock;
>>> -};
>>> -
>>> -struct snd_uac2_chip {
>>> -       struct uac2_rtd_params p_prm;
>>> -       struct uac2_rtd_params c_prm;
>>> -
>>> -       struct snd_card *card;
>>> -       struct snd_pcm *pcm;
>>> -
>>> -       /* timekeeping for the playback endpoint */
>>> -       unsigned int p_interval;
>>> -       unsigned int p_residue;
>>> -
>>> -       /* pre-calculated values for playback iso completion */
>>> -       unsigned int p_pktsize;
>>> -       unsigned int p_pktsize_residue;
>>> -       unsigned int p_framesize;
>>> +struct f_uac2 {
>>> +       struct g_audio g_audio;
>>> +       u8 ac_intf, as_in_intf, as_out_intf;
>>> +       u8 ac_alt, as_in_alt, as_out_alt;       /* needed for get_alt() */
>>>  };
>>>
>>> -#define BUFF_SIZE_MAX  (PAGE_SIZE * 16)
>>> -#define PRD_SIZE_MAX   PAGE_SIZE
>>> -#define MIN_PERIODS    4
>>> -
>>> -static struct snd_pcm_hardware uac2_pcm_hardware = {
>>> -       .info = SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER
>>> -                | SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID
>>> -                | SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME,
>>> -       .rates = SNDRV_PCM_RATE_CONTINUOUS,
>>> -       .periods_max = BUFF_SIZE_MAX / PRD_SIZE_MAX,
>>> -       .buffer_bytes_max = BUFF_SIZE_MAX,
>>> -       .period_bytes_max = PRD_SIZE_MAX,
>>> -       .periods_min = MIN_PERIODS,
>>> -};
>>> -
>>> -struct audio_dev {
>>> -       u8 ac_intf, ac_alt;
>>> -       u8 as_out_intf, as_out_alt;
>>> -       u8 as_in_intf, as_in_alt;
>>> -
>>> -       struct usb_ep *in_ep, *out_ep;
>>> -       struct usb_function func;
>>> -       struct usb_gadget *gadget;
>>> -
>>> -       /* The ALSA Sound Card it represents on the USB-Client side */
>>> -       struct snd_uac2_chip uac2;
>>> -};
>>> -
>>> -static inline
>>> -struct audio_dev *func_to_agdev(struct usb_function *f)
>>> +static inline struct f_uac2 *func_to_uac2(struct usb_function *f)
>>>  {
>>> -       return container_of(f, struct audio_dev, func);
>>> +       return container_of(f, struct f_uac2, g_audio.func);
>>>  }
>>>
>>>  static inline
>>> -struct audio_dev *uac2_to_agdev(struct snd_uac2_chip *u)
>>> -{
>>> -       return container_of(u, struct audio_dev, uac2);
>>> -}
>>> -
>>> -static inline
>>> -struct f_uac2_opts *agdev_to_uac2_opts(struct audio_dev *agdev)
>>> +struct f_uac2_opts *g_audio_to_uac2_opts(struct g_audio *agdev)
>>>  {
>>>         return container_of(agdev->func.fi, struct f_uac2_opts, func_inst);
>>>  }
>>>
>>> -static inline
>>> -uint num_channels(uint chanmask)
>>> -{
>>> -       uint num = 0;
>>> -
>>> -       while (chanmask) {
>>> -               num += (chanmask & 1);
>>> -               chanmask >>= 1;
>>> -       }
>>> -
>>> -       return num;
>>> -}
>>> -
>>> -static void
>>> -agdev_iso_complete(struct usb_ep *ep, struct usb_request *req)
>>> -{
>>> -       unsigned pending;
>>> -       unsigned long flags;
>>> -       unsigned int hw_ptr;
>>> -       bool update_alsa = false;
>>> -       int status = req->status;
>>> -       struct uac2_req *ur = req->context;
>>> -       struct snd_pcm_substream *substream;
>>> -       struct uac2_rtd_params *prm = ur->pp;
>>> -       struct snd_uac2_chip *uac2 = prm->uac2;
>>> -
>>> -       /* i/f shutting down */
>>> -       if (!prm->ep_enabled || req->status == -ESHUTDOWN)
>>> -               return;
>>> -
>>> -       /*
>>> -        * We can't really do much about bad xfers.
>>> -        * Afterall, the ISOCH xfers could fail legitimately.
>>> -        */
>>> -       if (status)
>>> -               pr_debug("%s: iso_complete status(%d) %d/%d\n",
>>> -                       __func__, status, req->actual, req->length);
>>> -
>>> -       substream = prm->ss;
>>> -
>>> -       /* Do nothing if ALSA isn't active */
>>> -       if (!substream)
>>> -               goto exit;
>>> -
>>> -       spin_lock_irqsave(&prm->lock, flags);
>>> -
>>> -       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
>>> -               /*
>>> -                * For each IN packet, take the quotient of the current data
>>> -                * rate and the endpoint's interval as the base packet size.
>>> -                * If there is a residue from this division, add it to the
>>> -                * residue accumulator.
>>> -                */
>>> -               req->length = uac2->p_pktsize;
>>> -               uac2->p_residue += uac2->p_pktsize_residue;
>>> -
>>> -               /*
>>> -                * Whenever there are more bytes in the accumulator than we
>>> -                * need to add one more sample frame, increase this packet's
>>> -                * size and decrease the accumulator.
>>> -                */
>>> -               if (uac2->p_residue / uac2->p_interval >= uac2->p_framesize) {
>>> -                       req->length += uac2->p_framesize;
>>> -                       uac2->p_residue -= uac2->p_framesize *
>>> -                                          uac2->p_interval;
>>> -               }
>>> -
>>> -               req->actual = req->length;
>>> -       }
>>> -
>>> -       pending = prm->hw_ptr % prm->period_size;
>>> -       pending += req->actual;
>>> -       if (pending >= prm->period_size)
>>> -               update_alsa = true;
>>> -
>>> -       hw_ptr = prm->hw_ptr;
>>> -       prm->hw_ptr = (prm->hw_ptr + req->actual) % prm->dma_bytes;
>>> -
>>> -       spin_unlock_irqrestore(&prm->lock, flags);
>>> -
>>> -       /* Pack USB load in ALSA ring buffer */
>>> -       pending = prm->dma_bytes - hw_ptr;
>>> -
>>> -       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
>>> -               if (unlikely(pending < req->actual)) {
>>> -                       memcpy(req->buf, prm->dma_area + hw_ptr, pending);
>>> -                       memcpy(req->buf + pending, prm->dma_area,
>>> -                              req->actual - pending);
>>> -               } else {
>>> -                       memcpy(req->buf, prm->dma_area + hw_ptr, req->actual);
>>> -               }
>>> -       } else {
>>> -               if (unlikely(pending < req->actual)) {
>>> -                       memcpy(prm->dma_area + hw_ptr, req->buf, pending);
>>> -                       memcpy(prm->dma_area, req->buf + pending,
>>> -                              req->actual - pending);
>>> -               } else {
>>> -                       memcpy(prm->dma_area + hw_ptr, req->buf, req->actual);
>>> -               }
>>> -       }
>>> -
>>> -exit:
>>> -       if (usb_ep_queue(ep, req, GFP_ATOMIC))
>>> -               dev_err(uac2->card->dev, "%d Error!\n", __LINE__);
>>> -
>>> -       if (update_alsa)
>>> -               snd_pcm_period_elapsed(substream);
>>> -
>>> -       return;
>>> -}
>>> -
>>> -static int
>>> -uac2_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
>>> -{
>>> -       struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
>>> -       struct audio_dev *agdev = uac2_to_agdev(uac2);
>>> -       struct f_uac2_opts *uac2_opts = agdev_to_uac2_opts(agdev);
>>> -       struct uac2_rtd_params *prm;
>>> -       unsigned long flags;
>>> -       int err = 0;
>>> -
>>> -       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
>>> -               prm = &uac2->p_prm;
>>> -       else
>>> -               prm = &uac2->c_prm;
>>> -
>>> -       spin_lock_irqsave(&prm->lock, flags);
>>> -
>>> -       /* Reset */
>>> -       prm->hw_ptr = 0;
>>> -
>>> -       switch (cmd) {
>>> -       case SNDRV_PCM_TRIGGER_START:
>>> -       case SNDRV_PCM_TRIGGER_RESUME:
>>> -               prm->ss = substream;
>>> -               break;
>>> -       case SNDRV_PCM_TRIGGER_STOP:
>>> -       case SNDRV_PCM_TRIGGER_SUSPEND:
>>> -               prm->ss = NULL;
>>> -               break;
>>> -       default:
>>> -               err = -EINVAL;
>>> -       }
>>> -
>>> -       spin_unlock_irqrestore(&prm->lock, flags);
>>> -
>>> -       /* Clear buffer after Play stops */
>>> -       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK && !prm->ss)
>>> -               memset(prm->rbuf, 0, prm->max_psize * uac2_opts->req_number);
>>> -
>>> -       return err;
>>> -}
>>> -
>>> -static snd_pcm_uframes_t uac2_pcm_pointer(struct snd_pcm_substream *substream)
>>> -{
>>> -       struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
>>> -       struct uac2_rtd_params *prm;
>>> -
>>> -       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
>>> -               prm = &uac2->p_prm;
>>> -       else
>>> -               prm = &uac2->c_prm;
>>> -
>>> -       return bytes_to_frames(substream->runtime, prm->hw_ptr);
>>> -}
>>> -
>>> -static int uac2_pcm_hw_params(struct snd_pcm_substream *substream,
>>> -                              struct snd_pcm_hw_params *hw_params)
>>> -{
>>> -       struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
>>> -       struct uac2_rtd_params *prm;
>>> -       int err;
>>> -
>>> -       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
>>> -               prm = &uac2->p_prm;
>>> -       else
>>> -               prm = &uac2->c_prm;
>>> -
>>> -       err = snd_pcm_lib_malloc_pages(substream,
>>> -                                       params_buffer_bytes(hw_params));
>>> -       if (err >= 0) {
>>> -               prm->dma_bytes = substream->runtime->dma_bytes;
>>> -               prm->dma_area = substream->runtime->dma_area;
>>> -               prm->period_size = params_period_bytes(hw_params);
>>> -       }
>>> -
>>> -       return err;
>>> -}
>>> -
>>> -static int uac2_pcm_hw_free(struct snd_pcm_substream *substream)
>>> -{
>>> -       struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
>>> -       struct uac2_rtd_params *prm;
>>> -
>>> -       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
>>> -               prm = &uac2->p_prm;
>>> -       else
>>> -               prm = &uac2->c_prm;
>>> -
>>> -       prm->dma_area = NULL;
>>> -       prm->dma_bytes = 0;
>>> -       prm->period_size = 0;
>>> -
>>> -       return snd_pcm_lib_free_pages(substream);
>>> -}
>>> -
>>> -static int uac2_pcm_open(struct snd_pcm_substream *substream)
>>> -{
>>> -       struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
>>> -       struct snd_pcm_runtime *runtime = substream->runtime;
>>> -       struct audio_dev *audio_dev;
>>> -       struct f_uac2_opts *opts;
>>> -       int p_ssize, c_ssize;
>>> -       int p_srate, c_srate;
>>> -       int p_chmask, c_chmask;
>>> -
>>> -       audio_dev = uac2_to_agdev(uac2);
>>> -       opts = container_of(audio_dev->func.fi, struct f_uac2_opts, func_inst);
>>> -       p_ssize = opts->p_ssize;
>>> -       c_ssize = opts->c_ssize;
>>> -       p_srate = opts->p_srate;
>>> -       c_srate = opts->c_srate;
>>> -       p_chmask = opts->p_chmask;
>>> -       c_chmask = opts->c_chmask;
>>> -       uac2->p_residue = 0;
>>> -
>>> -       runtime->hw = uac2_pcm_hardware;
>>> -
>>> -       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
>>> -               spin_lock_init(&uac2->p_prm.lock);
>>> -               runtime->hw.rate_min = p_srate;
>>> -               switch (p_ssize) {
>>> -               case 3:
>>> -                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
>>> -                       break;
>>> -               case 4:
>>> -                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
>>> -                       break;
>>> -               default:
>>> -                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
>>> -                       break;
>>> -               }
>>> -               runtime->hw.channels_min = num_channels(p_chmask);
>>> -               runtime->hw.period_bytes_min = 2 * uac2->p_prm.max_psize
>>> -                                               / runtime->hw.periods_min;
>>> -       } else {
>>> -               spin_lock_init(&uac2->c_prm.lock);
>>> -               runtime->hw.rate_min = c_srate;
>>> -               switch (c_ssize) {
>>> -               case 3:
>>> -                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
>>> -                       break;
>>> -               case 4:
>>> -                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
>>> -                       break;
>>> -               default:
>>> -                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
>>> -                       break;
>>> -               }
>>> -               runtime->hw.channels_min = num_channels(c_chmask);
>>> -               runtime->hw.period_bytes_min = 2 * uac2->c_prm.max_psize
>>> -                                               / runtime->hw.periods_min;
>>> -       }
>>> -
>>> -       runtime->hw.rate_max = runtime->hw.rate_min;
>>> -       runtime->hw.channels_max = runtime->hw.channels_min;
>>> -
>>> -       snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
>>> -
>>> -       return 0;
>>> -}
>>> -
>>> -/* ALSA cries without these function pointers */
>>> -static int uac2_pcm_null(struct snd_pcm_substream *substream)
>>> -{
>>> -       return 0;
>>> -}
>>> -
>>> -static struct snd_pcm_ops uac2_pcm_ops = {
>>> -       .open = uac2_pcm_open,
>>> -       .close = uac2_pcm_null,
>>> -       .ioctl = snd_pcm_lib_ioctl,
>>> -       .hw_params = uac2_pcm_hw_params,
>>> -       .hw_free = uac2_pcm_hw_free,
>>> -       .trigger = uac2_pcm_trigger,
>>> -       .pointer = uac2_pcm_pointer,
>>> -       .prepare = uac2_pcm_null,
>>> -};
>>> -
>>> -static int snd_uac2_probe(struct audio_dev *audio_dev)
>>> -{
>>> -       struct snd_uac2_chip *uac2 = &audio_dev->uac2;
>>> -       struct snd_card *card;
>>> -       struct snd_pcm *pcm;
>>> -       struct f_uac2_opts *opts;
>>> -       int err;
>>> -       int p_chmask, c_chmask;
>>> -
>>> -       opts = container_of(audio_dev->func.fi, struct f_uac2_opts, func_inst);
>>> -       p_chmask = opts->p_chmask;
>>> -       c_chmask = opts->c_chmask;
>>> -
>>> -       /* Choose any slot, with no id */
>>> -       err = snd_card_new(&audio_dev->gadget->dev,
>>> -                       -1, NULL, THIS_MODULE, 0, &card);
>>> -       if (err < 0)
>>> -               return err;
>>> -
>>> -       uac2->card = card;
>>> -
>>> -       /*
>>> -        * Create first PCM device
>>> -        * Create a substream only for non-zero channel streams
>>> -        */
>>> -       err = snd_pcm_new(uac2->card, "UAC2 PCM", 0,
>>> -                              p_chmask ? 1 : 0, c_chmask ? 1 : 0, &pcm);
>>> -       if (err < 0)
>>> -               goto snd_fail;
>>> -
>>> -       strcpy(pcm->name, "UAC2 PCM");
>>> -       pcm->private_data = uac2;
>>> -
>>> -       uac2->pcm = pcm;
>>> -
>>> -       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &uac2_pcm_ops);
>>> -       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &uac2_pcm_ops);
>>> -
>>> -       strcpy(card->driver, "UAC2_Gadget");
>>> -       strcpy(card->shortname, "UAC2_Gadget");
>>> -       sprintf(card->longname, "UAC2_Gadget %i", card->dev->id);
>>> -
>>> -       snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
>>> -               snd_dma_continuous_data(GFP_KERNEL), 0, BUFF_SIZE_MAX);
>>> -
>>> -       err = snd_card_register(card);
>>> -
>>> -       if (!err)
>>> -               return 0;
>>> -
>>> -snd_fail:
>>> -       snd_card_free(card);
>>> -
>>> -       uac2->pcm = NULL;
>>> -       uac2->card = NULL;
>>> -
>>> -       return err;
>>> -}
>>> -
>>> -static int snd_uac2_remove(struct audio_dev *audio_dev)
>>> -{
>>> -       struct snd_card *card = audio_dev->uac2.card;
>>> -
>>> -       if (card)
>>> -               return snd_card_free(card);
>>> -
>>> -       return 0;
>>> -}
>>> -
>>> -
>>>  /* --------- USB Function Interface ------------- */
>>>
>>>  enum {
>>> @@ -886,32 +451,6 @@ struct cntrl_range_lay3 {
>>>         __u32   dRES;
>>>  } __packed;
>>>
>>> -static inline void
>>> -free_ep(struct uac2_rtd_params *prm, struct usb_ep *ep)
>>> -{
>>> -       struct snd_uac2_chip *uac2 = prm->uac2;
>>> -       struct audio_dev *agdev = uac2_to_agdev(uac2);
>>> -       struct f_uac2_opts *uac2_opts = agdev_to_uac2_opts(agdev);
>>> -       int i;
>>> -
>>> -       if (!prm->ep_enabled)
>>> -               return;
>>> -
>>> -       prm->ep_enabled = false;
>>> -
>>> -       for (i = 0; i < uac2_opts->req_number; i++) {
>>> -               if (prm->ureq[i].req) {
>>> -                       usb_ep_dequeue(ep, prm->ureq[i].req);
>>> -                       usb_ep_free_request(ep, prm->ureq[i].req);
>>> -                       prm->ureq[i].req = NULL;
>>> -               }
>>> -       }
>>> -
>>> -       if (usb_ep_disable(ep))
>>> -               dev_err(uac2->card->dev,
>>> -                       "%s:%d Error!\n", __func__, __LINE__);
>>> -}
>>> -
>>>  static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>         struct usb_endpoint_descriptor *ep_desc,
>>>         unsigned int factor, bool is_playback)
>>> @@ -938,12 +477,11 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>  static int
>>>  afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
>>>  {
>>> -       struct audio_dev *agdev = func_to_agdev(fn);
>>> -       struct snd_uac2_chip *uac2 = &agdev->uac2;
>>> +       struct f_uac2 *uac2 = func_to_uac2(fn);
>>> +       struct g_audio *agdev = func_to_g_audio(fn);
>>>         struct usb_composite_dev *cdev = cfg->cdev;
>>>         struct usb_gadget *gadget = cdev->gadget;
>>>         struct device *dev = &gadget->dev;
>>> -       struct uac2_rtd_params *prm;
>>>         struct f_uac2_opts *uac2_opts;
>>>         struct usb_string *us;
>>>         int ret;
>>> @@ -990,8 +528,8 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>                 return ret;
>>>         }
>>>         std_ac_if_desc.bInterfaceNumber = ret;
>>> -       agdev->ac_intf = ret;
>>> -       agdev->ac_alt = 0;
>>> +       uac2->ac_intf = ret;
>>> +       uac2->ac_alt = 0;
>>>
>>>         ret = usb_interface_id(cfg, fn);
>>>         if (ret < 0) {
>>> @@ -1000,8 +538,8 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>         }
>>>         std_as_out_if0_desc.bInterfaceNumber = ret;
>>>         std_as_out_if1_desc.bInterfaceNumber = ret;
>>> -       agdev->as_out_intf = ret;
>>> -       agdev->as_out_alt = 0;
>>> +       uac2->as_out_intf = ret;
>>> +       uac2->as_out_alt = 0;
>>>
>>>         ret = usb_interface_id(cfg, fn);
>>>         if (ret < 0) {
>>> @@ -1010,8 +548,8 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>         }
>>>         std_as_in_if0_desc.bInterfaceNumber = ret;
>>>         std_as_in_if1_desc.bInterfaceNumber = ret;
>>> -       agdev->as_in_intf = ret;
>>> -       agdev->as_in_alt = 0;
>>> +       uac2->as_in_intf = ret;
>>> +       uac2->as_in_alt = 0;
>>>
>>>         agdev->out_ep = usb_ep_autoconfig(gadget, &fs_epout_desc);
>>>         if (!agdev->out_ep) {
>>> @@ -1025,15 +563,17 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>                 return ret;
>>>         }
>>>
>>> -       uac2->p_prm.uac2 = uac2;
>>> -       uac2->c_prm.uac2 = uac2;
>>> -
>>>         /* Calculate wMaxPacketSize according to audio bandwidth */
>>>         set_ep_max_packet_size(uac2_opts, &fs_epin_desc, 1000, true);
>>>         set_ep_max_packet_size(uac2_opts, &fs_epout_desc, 1000, false);
>>>         set_ep_max_packet_size(uac2_opts, &hs_epin_desc, 8000, true);
>>>         set_ep_max_packet_size(uac2_opts, &hs_epout_desc, 8000, false);
>>>
>>> +       agdev->in_ep_maxpsize = max(fs_epin_desc.wMaxPacketSize,
>>> +                                       hs_epin_desc.wMaxPacketSize);
>>> +       agdev->out_ep_maxpsize = max(fs_epout_desc.wMaxPacketSize,
>>> +                                       hs_epout_desc.wMaxPacketSize);
>>> +
>>>         hs_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
>>>         hs_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;
>>>
>>> @@ -1044,46 +584,18 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>
>>>         agdev->gadget = gadget;
>>>
>>> -       prm = &agdev->uac2.c_prm;
>>> -       prm->max_psize = hs_epout_desc.wMaxPacketSize;
>>> -       prm->ureq = kcalloc(uac2_opts->req_number, sizeof(struct uac2_req),
>>> -                       GFP_KERNEL);
>>> -       if (!prm->ureq) {
>>> -               ret = -ENOMEM;
>>> -               goto err_free_descs;
>>> -       }
>>> -       prm->rbuf = kcalloc(uac2_opts->req_number, prm->max_psize, GFP_KERNEL);
>>> -       if (!prm->rbuf) {
>>> -               prm->max_psize = 0;
>>> -               ret = -ENOMEM;
>>> -               goto err_free_descs;
>>> -       }
>>> -
>>> -       prm = &agdev->uac2.p_prm;
>>> -       prm->max_psize = hs_epin_desc.wMaxPacketSize;
>>> -       prm->ureq = kcalloc(uac2_opts->req_number, sizeof(struct uac2_req),
>>> -                       GFP_KERNEL);
>>> -       if (!prm->ureq) {
>>> -               ret = -ENOMEM;
>>> -               goto err_free_descs;
>>> -       }
>>> -       prm->rbuf = kcalloc(uac2_opts->req_number, prm->max_psize, GFP_KERNEL);
>>> -       if (!prm->rbuf) {
>>> -               prm->max_psize = 0;
>>> -               ret = -ENOMEM;
>>> -               goto err_no_memory;
>>> -       }
>>> -
>>> -       ret = snd_uac2_probe(agdev);
>>> +       agdev->params.p_chmask = uac2_opts->p_chmask;
>>> +       agdev->params.p_srate = uac2_opts->p_srate;
>>> +       agdev->params.p_ssize = uac2_opts->p_ssize;
>>> +       agdev->params.c_chmask = uac2_opts->c_chmask;
>>> +       agdev->params.c_srate = uac2_opts->c_srate;
>>> +       agdev->params.c_ssize = uac2_opts->c_ssize;
>>> +       agdev->params.req_number = uac2_opts->req_number;
>>> +       ret = g_audio_setup(agdev, "UAC2 PCM", "UAC2_Gadget");
>>>         if (ret)
>>> -               goto err_no_memory;
>>> +               goto err_free_descs;
>>>         return 0;
>>>
>>> -err_no_memory:
>>> -       kfree(agdev->uac2.p_prm.ureq);
>>> -       kfree(agdev->uac2.c_prm.ureq);
>>> -       kfree(agdev->uac2.p_prm.rbuf);
>>> -       kfree(agdev->uac2.c_prm.rbuf);
>>>  err_free_descs:
>>>         usb_free_all_descriptors(fn);
>>>         agdev->gadget = NULL;
>>> @@ -1094,15 +606,10 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>  afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
>>>  {
>>>         struct usb_composite_dev *cdev = fn->config->cdev;
>>> -       struct audio_dev *agdev = func_to_agdev(fn);
>>> -       struct f_uac2_opts *opts = agdev_to_uac2_opts(agdev);
>>> -       struct snd_uac2_chip *uac2 = &agdev->uac2;
>>> +       struct f_uac2 *uac2 = func_to_uac2(fn);
>>>         struct usb_gadget *gadget = cdev->gadget;
>>>         struct device *dev = &gadget->dev;
>>> -       struct usb_request *req;
>>> -       struct usb_ep *ep;
>>> -       struct uac2_rtd_params *prm;
>>> -       int req_len, i;
>>> +       int ret = 0;
>>>
>>>         /* No i/f has more than 2 alt settings */
>>>         if (alt > 1) {
>>> @@ -1110,7 +617,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>                 return -EINVAL;
>>>         }
>>>
>>> -       if (intf == agdev->ac_intf) {
>>> +       if (intf == uac2->ac_intf) {
>>>                 /* Control I/f has only 1 AltSetting - 0 */
>>>                 if (alt) {
>>>                         dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
>>> @@ -1119,92 +626,40 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>                 return 0;
>>>         }
>>>
>>> -       if (intf == agdev->as_out_intf) {
>>> -               ep = agdev->out_ep;
>>> -               prm = &uac2->c_prm;
>>> -               config_ep_by_speed(gadget, fn, ep);
>>> -               agdev->as_out_alt = alt;
>>> -               req_len = prm->max_psize;
>>> -       } else if (intf == agdev->as_in_intf) {
>>> -               unsigned int factor, rate;
>>> -               struct usb_endpoint_descriptor *ep_desc;
>>> -
>>> -               ep = agdev->in_ep;
>>> -               prm = &uac2->p_prm;
>>> -               config_ep_by_speed(gadget, fn, ep);
>>> -               agdev->as_in_alt = alt;
>>> -
>>> -               /* pre-calculate the playback endpoint's interval */
>>> -               if (gadget->speed == USB_SPEED_FULL) {
>>> -                       ep_desc = &fs_epin_desc;
>>> -                       factor = 1000;
>>> -               } else {
>>> -                       ep_desc = &hs_epin_desc;
>>> -                       factor = 8000;
>>> -               }
>>> -
>>> -               /* pre-compute some values for iso_complete() */
>>> -               uac2->p_framesize = opts->p_ssize *
>>> -                                   num_channels(opts->p_chmask);
>>> -               rate = opts->p_srate * uac2->p_framesize;
>>> -               uac2->p_interval = factor / (1 << (ep_desc->bInterval - 1));
>>> -               uac2->p_pktsize = min_t(unsigned int, rate / uac2->p_interval,
>>> -                                       prm->max_psize);
>>> +       if (intf == uac2->as_out_intf) {
>>> +               uac2->as_out_alt = alt;
>>>
>>> -               if (uac2->p_pktsize < prm->max_psize)
>>> -                       uac2->p_pktsize_residue = rate % uac2->p_interval;
>>> +               if (alt)
>>> +                       ret = u_audio_start_capture(&uac2->g_audio);
>>>                 else
>>> -                       uac2->p_pktsize_residue = 0;
>>> +                       u_audio_stop_capture(&uac2->g_audio);
>>> +       } else if (intf == uac2->as_in_intf) {
>>> +               uac2->as_in_alt = alt;
>>>
>>> -               req_len = uac2->p_pktsize;
>>> -               uac2->p_residue = 0;
>>> +               if (alt)
>>> +                       ret = u_audio_start_playback(&uac2->g_audio);
>>> +               else
>>> +                       u_audio_stop_playback(&uac2->g_audio);
>>>         } else {
>>>                 dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
>>>                 return -EINVAL;
>>>         }
>>>
>>> -       if (alt == 0) {
>>> -               free_ep(prm, ep);
>>> -               return 0;
>>> -       }
>>> -
>>> -       prm->ep_enabled = true;
>>> -       usb_ep_enable(ep);
>>> -
>>> -       for (i = 0; i < opts->req_number; i++) {
>>> -               if (!prm->ureq[i].req) {
>>> -                       req = usb_ep_alloc_request(ep, GFP_ATOMIC);
>>> -                       if (req == NULL)
>>> -                               return -ENOMEM;
>>> -
>>> -                       prm->ureq[i].req = req;
>>> -                       prm->ureq[i].pp = prm;
>>> -
>>> -                       req->zero = 0;
>>> -                       req->context = &prm->ureq[i];
>>> -                       req->length = req_len;
>>> -                       req->complete = agdev_iso_complete;
>>> -                       req->buf = prm->rbuf + i * prm->max_psize;
>>> -               }
>>> -
>>> -               if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
>>> -                       dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
>>> -       }
>>> -
>>> -       return 0;
>>> +       return ret;
>>>  }
>>>
>>>  static int
>>>  afunc_get_alt(struct usb_function *fn, unsigned intf)
>>>  {
>>> -       struct audio_dev *agdev = func_to_agdev(fn);
>>> -
>>> -       if (intf == agdev->ac_intf)
>>> -               return agdev->ac_alt;
>>> -       else if (intf == agdev->as_out_intf)
>>> -               return agdev->as_out_alt;
>>> -       else if (intf == agdev->as_in_intf)
>>> -               return agdev->as_in_alt;
>>> +       struct f_uac2 *uac2 = func_to_uac2(fn);
>>> +       struct g_audio *agdev = func_to_g_audio(fn);
>>> +
>>> +       if (intf == uac2->ac_intf)
>>> +               return uac2->ac_alt;
>>> +       else if (intf == uac2->as_out_intf)
>>> +               return uac2->as_out_alt;
>>> +       else if (intf == uac2->as_in_intf)
>>> +               return uac2->as_in_alt;
>>>         else
>>>                 dev_err(&agdev->gadget->dev,
>>>                         "%s:%d Invalid Interface %d!\n",
>>> @@ -1216,21 +671,19 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>  static void
>>>  afunc_disable(struct usb_function *fn)
>>>  {
>>> -       struct audio_dev *agdev = func_to_agdev(fn);
>>> -       struct snd_uac2_chip *uac2 = &agdev->uac2;
>>> -
>>> -       free_ep(&uac2->p_prm, agdev->in_ep);
>>> -       agdev->as_in_alt = 0;
>>> +       struct f_uac2 *uac2 = func_to_uac2(fn);
>>>
>>> -       free_ep(&uac2->c_prm, agdev->out_ep);
>>> -       agdev->as_out_alt = 0;
>>> +       uac2->as_in_alt = 0;
>>> +       uac2->as_out_alt = 0;
>>> +       u_audio_stop_capture(&uac2->g_audio);
>>> +       u_audio_stop_playback(&uac2->g_audio);
>>>  }
>>>
>>>  static int
>>>  in_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
>>>  {
>>>         struct usb_request *req = fn->config->cdev->req;
>>> -       struct audio_dev *agdev = func_to_agdev(fn);
>>> +       struct g_audio *agdev = func_to_g_audio(fn);
>>>         struct f_uac2_opts *opts;
>>>         u16 w_length = le16_to_cpu(cr->wLength);
>>>         u16 w_index = le16_to_cpu(cr->wIndex);
>>> @@ -1240,7 +693,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>         int value = -EOPNOTSUPP;
>>>         int p_srate, c_srate;
>>>
>>> -       opts = agdev_to_uac2_opts(agdev);
>>> +       opts = g_audio_to_uac2_opts(agdev);
>>>         p_srate = opts->p_srate;
>>>         c_srate = opts->c_srate;
>>>
>>> @@ -1271,7 +724,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>  in_rq_range(struct usb_function *fn, const struct usb_ctrlrequest *cr)
>>>  {
>>>         struct usb_request *req = fn->config->cdev->req;
>>> -       struct audio_dev *agdev = func_to_agdev(fn);
>>> +       struct g_audio *agdev = func_to_g_audio(fn);
>>>         struct f_uac2_opts *opts;
>>>         u16 w_length = le16_to_cpu(cr->wLength);
>>>         u16 w_index = le16_to_cpu(cr->wIndex);
>>> @@ -1282,7 +735,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>         int value = -EOPNOTSUPP;
>>>         int p_srate, c_srate;
>>>
>>> -       opts = agdev_to_uac2_opts(agdev);
>>> +       opts = g_audio_to_uac2_opts(agdev);
>>>         p_srate = opts->p_srate;
>>>         c_srate = opts->c_srate;
>>>
>>> @@ -1336,11 +789,12 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>  static int
>>>  setup_rq_inf(struct usb_function *fn, const struct usb_ctrlrequest *cr)
>>>  {
>>> -       struct audio_dev *agdev = func_to_agdev(fn);
>>> +       struct f_uac2 *uac2 = func_to_uac2(fn);
>>> +       struct g_audio *agdev = func_to_g_audio(fn);
>>>         u16 w_index = le16_to_cpu(cr->wIndex);
>>>         u8 intf = w_index & 0xff;
>>>
>>> -       if (intf != agdev->ac_intf) {
>>> +       if (intf != uac2->ac_intf) {
>>>                 dev_err(&agdev->gadget->dev,
>>>                         "%s:%d Error!\n", __func__, __LINE__);
>>>                 return -EOPNOTSUPP;
>>> @@ -1358,7 +812,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
>>>  afunc_setup(struct usb_function *fn, const struct usb_ctrlrequest *cr)
>>>  {
>>>         struct usb_composite_dev *cdev = fn->config->cdev;
>>> -       struct audio_dev *agdev = func_to_agdev(fn);
>>> +       struct g_audio *agdev = func_to_g_audio(fn);
>>>         struct usb_request *req = cdev->req;
>>>         u16 w_length = le16_to_cpu(cr->wLength);
>>>         int value = -EOPNOTSUPP;
>>> @@ -1504,10 +958,10 @@ static struct usb_function_instance *afunc_alloc_inst(void)
>>>
>>>  static void afunc_free(struct usb_function *f)
>>>  {
>>> -       struct audio_dev *agdev;
>>> +       struct g_audio *agdev;
>>>         struct f_uac2_opts *opts;
>>>
>>> -       agdev = func_to_agdev(f);
>>> +       agdev = func_to_g_audio(f);
>>>         opts = container_of(f->fi, struct f_uac2_opts, func_inst);
>>>         kfree(agdev);
>>>         mutex_lock(&opts->lock);
>>> @@ -1517,17 +971,9 @@ static void afunc_free(struct usb_function *f)
>>>
>>>  static void afunc_unbind(struct usb_configuration *c, struct usb_function *f)
>>>  {
>>> -       struct audio_dev *agdev = func_to_agdev(f);
>>> -       struct uac2_rtd_params *prm;
>>> -
>>> -       snd_uac2_remove(agdev);
>>> -
>>> -       prm = &agdev->uac2.p_prm;
>>> -       kfree(prm->rbuf);
>>> +       struct g_audio *agdev = func_to_g_audio(f);
>>>
>>> -       prm = &agdev->uac2.c_prm;
>>> -       kfree(prm->rbuf);
>>> -       kfree(prm->ureq);
>>> +       g_audio_cleanup(agdev);
>>>         usb_free_all_descriptors(f);
>>>
>>>         agdev->gadget = NULL;
>>> @@ -1535,11 +981,11 @@ static void afunc_unbind(struct usb_configuration *c, struct usb_function *f)
>>>
>>>  static struct usb_function *afunc_alloc(struct usb_function_instance *fi)
>>>  {
>>> -       struct audio_dev *agdev;
>>> +       struct f_uac2   *uac2;
>>>         struct f_uac2_opts *opts;
>>>
>>> -       agdev = kzalloc(sizeof(*agdev), GFP_KERNEL);
>>> -       if (agdev == NULL)
>>> +       uac2 = kzalloc(sizeof(*uac2), GFP_KERNEL);
>>> +       if (uac2 == NULL)
>>>                 return ERR_PTR(-ENOMEM);
>>>
>>>         opts = container_of(fi, struct f_uac2_opts, func_inst);
>>> @@ -1547,19 +993,20 @@ static struct usb_function *afunc_alloc(struct usb_function_instance *fi)
>>>         ++opts->refcnt;
>>>         mutex_unlock(&opts->lock);
>>>
>>> -       agdev->func.name = "uac2_func";
>>> -       agdev->func.bind = afunc_bind;
>>> -       agdev->func.unbind = afunc_unbind;
>>> -       agdev->func.set_alt = afunc_set_alt;
>>> -       agdev->func.get_alt = afunc_get_alt;
>>> -       agdev->func.disable = afunc_disable;
>>> -       agdev->func.setup = afunc_setup;
>>> -       agdev->func.free_func = afunc_free;
>>> +       uac2->g_audio.func.name = "uac2_func";
>>> +       uac2->g_audio.func.bind = afunc_bind;
>>> +       uac2->g_audio.func.unbind = afunc_unbind;
>>> +       uac2->g_audio.func.set_alt = afunc_set_alt;
>>> +       uac2->g_audio.func.get_alt = afunc_get_alt;
>>> +       uac2->g_audio.func.disable = afunc_disable;
>>> +       uac2->g_audio.func.setup = afunc_setup;
>>> +       uac2->g_audio.func.free_func = afunc_free;
>>>
>>> -       return &agdev->func;
>>> +       return &uac2->g_audio.func;
>>>  }
>>>
>>>  DECLARE_USB_FUNCTION_INIT(uac2, afunc_alloc_inst, afunc_alloc);
>>>  MODULE_LICENSE("GPL");
>>>  MODULE_AUTHOR("Yadwinder Singh");
>>>  MODULE_AUTHOR("Jaswinder Singh");
>>> +MODULE_AUTHOR("Ruslan Bilovol");
>>>
>> drivers/usb/gadget/function/f_uac2.c  | 721 ++++------------------------------
>>
>> Basically you move out ALSA sound card implementation and  %s/agdev/uac2/
>> I am not sure churn warrants a MODULE_AUTHOR. People have made far
>> more important contribution to the UAC2,
>
> Yes, I added it after cumulative effect of this patch and patch 1/3
> where I removed  platform driver/device creation from f_uac2.
> I haven't find any rules on this and just counted changed lines,
> however in this particular case it's better to use something
> like MODULE_CLEANER(). Just joking :)
>
> I'll remove this line then.
>
Thanks, that will be fair to all.

>>
>>
>>> diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
>>> new file mode 100644
>>> index 0000000..8ee65b8
>>> --- /dev/null
>>> +++ b/drivers/usb/gadget/function/u_audio.c
>>> @@ -0,0 +1,661 @@
>>> +/*
>>> + * u_audio.c -- interface to USB gadget "ALSA sound card" utilities
>>> + *
>>> + * Copyright (C) 2016
>>> + * Author: Ruslan Bilovol <ruslan.bilovol@...il.com>
>>> + *
>>> + * Based on f_uac2.c which is:
>>> + *    Copyright (C) 2011
>>> + *    Yadwinder Singh (yadi.brar01@...il.com)
>>> + *    Jaswinder Singh (jaswinder.singh@...aro.org)
>>> + *
>> Again this is not "based on", rather where you paste the code you cut
>> from f_uac2.c
>> Of course you also pad it with minor changes to make it useful to your
>> uac1 code. I am not happy with losing copyright on the sound card
>> implementation for the UAC drivers.
>
> I don't remember why I wrote it as "based on" back in 2016,
> probably looking into another patches as example. As per my
> understanding, "based on" + your name in Copyright means
> that you still continue to hold copyright on the sound card
> implementation (otherwise why mention it?).
>
I don't think copyright spreads by inspiration :)

But seriously, we have to be careful if we set a precedence here. You
write some important piece of code and assert copyright over it.
Sometime later someone finds a reason to move that code to a new file
and adds his/her copyright while relegating you to just "inspiration".
You can contest the code was your copyright originally but is surely
tougher than having the code clearly state that fact.

> However I'm not a lawyer so can't say for sure.
> Will change this description in next patchset to make it clear,
> so you won't loose your copyright.
>
Thank you.

Powered by blists - more mailing lists