Date:   Tue, 17 Apr 2018 15:34:32 +0300
From:   Oleksandr Andrushchenko <Oleksandr_Andrushchenko@...m.com>
To:     Juergen Gross <jgross@...e.com>,
        Oleksandr Andrushchenko <andr2000@...il.com>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        alsa-devel@...a-project.org, boris.ostrovsky@...cle.com,
        konrad.wilk@...cle.com, perex@...ex.cz, tiwai@...e.com
Subject: Re: [PATCH v2 5/5] ALSA: xen-front: Implement ALSA virtual sound
 driver

On 04/17/2018 03:32 PM, Juergen Gross wrote:
> On 17/04/18 14:26, Oleksandr Andrushchenko wrote:
>> On 04/17/2018 02:32 PM, Oleksandr Andrushchenko wrote:
>>> On 04/16/2018 05:09 PM, Juergen Gross wrote:
>>>> On 16/04/18 08:24, Oleksandr Andrushchenko wrote:
>>>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>>>>
>>>>> Implement essential initialization of the sound driver:
>>>>>     - introduce required data structures
>>>>>     - handle driver registration
>>>>>     - handle sound card registration
>>>>>     - register sound driver on backend connection
>>>>>     - remove sound driver on backend disconnect
>>>>>
>>>>> Initialize virtual sound card with streams according to the
>>>>> Xen store configuration.
>>>>>
>>>>> Implement ALSA driver operations including:
>>>>> - manage frontend/backend shared buffers
>>>>> - manage Xen bus event channel states
>>>>>
>>>>> Implement requests from front to back for ALSA
>>>>> PCM operations.
>>>>>    - report ALSA period elapsed event: handle XENSND_EVT_CUR_POS
>>>>>      notifications from the backend when stream position advances
>>>>>      during playback/capture. The event carries a value of how
>>>>>      many octets were played/captured at the time of the event.
>>>>>    - implement explicit stream parameter negotiation between
>>>>>      backend and frontend: handle XENSND_OP_HW_PARAM_QUERY request
>>>>>      to read/update configuration space for the parameter given:
>>>>>      request passes desired parameter interval and the response to
>>>>>      this request returns min/max interval for the parameter to be used.
>>>>>
>>>>> Signed-off-by: Oleksandr Andrushchenko
>>>>> <oleksandr_andrushchenko@...m.com>
>>>>> ---
>>>>>    sound/xen/Makefile                |   3 +-
>>>>>    sound/xen/xen_snd_front.c         | 193 ++++++++-
>>>>>    sound/xen/xen_snd_front.h         |  28 ++
>>>>>    sound/xen/xen_snd_front_alsa.c    | 830
>>>>> ++++++++++++++++++++++++++++++++++++++
>>>>>    sound/xen/xen_snd_front_alsa.h    |  23 ++
>>>>>    sound/xen/xen_snd_front_evtchnl.c |   6 +-
>>>>>    6 files changed, 1080 insertions(+), 3 deletions(-)
>>>>>    create mode 100644 sound/xen/xen_snd_front_alsa.c
>>>>>    create mode 100644 sound/xen/xen_snd_front_alsa.h
>>>>>
>>>>> diff --git a/sound/xen/Makefile b/sound/xen/Makefile
>>>>> index f028bc30af5d..1e6470ecc2f2 100644
>>>>> --- a/sound/xen/Makefile
>>>>> +++ b/sound/xen/Makefile
>>>>> @@ -3,6 +3,7 @@
>>>>>    snd_xen_front-objs := xen_snd_front.o \
>>>>>                  xen_snd_front_cfg.o \
>>>>>                  xen_snd_front_evtchnl.o \
>>>>> -              xen_snd_front_shbuf.o
>>>>> +              xen_snd_front_shbuf.o \
>>>>> +              xen_snd_front_alsa.o
>>>>>      obj-$(CONFIG_SND_XEN_FRONTEND) += snd_xen_front.o
>>>>> diff --git a/sound/xen/xen_snd_front.c b/sound/xen/xen_snd_front.c
>>>>> index 0569c6c596a3..1fef253ea21a 100644
>>>>> --- a/sound/xen/xen_snd_front.c
>>>>> +++ b/sound/xen/xen_snd_front.c
>>>>> @@ -19,10 +19,201 @@
>>>>>    #include <xen/interface/io/sndif.h>
>>>>>      #include "xen_snd_front.h"
>>>>> +#include "xen_snd_front_alsa.h"
>>>>>    #include "xen_snd_front_evtchnl.h"
>>>>> +#include "xen_snd_front_shbuf.h"
>>>>> +
>>>>> +static struct xensnd_req *
>>>>> +be_stream_prepare_req(struct xen_snd_front_evtchnl *evtchnl, u8
>>>>> operation)
>>>>> +{
>>>>> +    struct xensnd_req *req;
>>>>> +
>>>>> +    req = RING_GET_REQUEST(&evtchnl->u.req.ring,
>>>>> +                   evtchnl->u.req.ring.req_prod_pvt);
>>>>> +    req->operation = operation;
>>>>> +    req->id = evtchnl->evt_next_id++;
>>>>> +    evtchnl->evt_id = req->id;
>>>>> +    return req;
>>>>> +}
>>>>> +
>>>>> +static int be_stream_do_io(struct xen_snd_front_evtchnl *evtchnl)
>>>>> +{
>>>>> +    if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
>>>>> +        return -EIO;
>>>>> +
>>>>> +    reinit_completion(&evtchnl->u.req.completion);
>>>>> +    xen_snd_front_evtchnl_flush(evtchnl);
>>>>> +    return 0;
>>>>> +}
>>>>> +
>>>>> +static int be_stream_wait_io(struct xen_snd_front_evtchnl *evtchnl)
>>>>> +{
>>>>> +    if (wait_for_completion_timeout(&evtchnl->u.req.completion,
>>>>> +            msecs_to_jiffies(VSND_WAIT_BACK_MS)) <= 0)
>>>>> +        return -ETIMEDOUT;
>>>>> +
>>>>> +    return evtchnl->u.req.resp_status;
>>>>> +}
>>>>> +
>>>>> +int xen_snd_front_stream_query_hw_param(struct
>>>>> xen_snd_front_evtchnl *evtchnl,
>>>>> +                    struct xensnd_query_hw_param *hw_param_req,
>>>>> +                    struct xensnd_query_hw_param *hw_param_resp)
>>>>> +{
>>>>> +    struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>>> +    struct xensnd_req *req;
>>>>> +    unsigned long flags;
>>>>> +    int ret;
>>>>> +
>>>>> +    mutex_lock(&evtchnl->u.req.req_io_lock);
>>>>> +
>>>>> +    spin_lock_irqsave(&front_info->io_lock, flags);
>>>>> +    req = be_stream_prepare_req(evtchnl, XENSND_OP_HW_PARAM_QUERY);
>>>>> +    req->op.hw_param = *hw_param_req;
>>>>> +
>>>>> +    ret = be_stream_do_io(evtchnl);
>>>>> +    spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>>> +
>>>>> +    if (ret == 0)
>>>>> +        ret = be_stream_wait_io(evtchnl);
>>>>> +
>>>>> +    if (ret == 0)
>>>>> +        *hw_param_resp = evtchnl->u.req.resp.hw_param;
>>>>> +
>>>>> +    mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>>> +    return ret;
>>>>> +}
>>>>> +
>>>>> +int xen_snd_front_stream_prepare(struct xen_snd_front_evtchnl
>>>>> *evtchnl,
>>>>> +                 struct xen_snd_front_shbuf *sh_buf,
>>>>> +                 u8 format, unsigned int channels,
>>>>> +                 unsigned int rate, u32 buffer_sz,
>>>>> +                 u32 period_sz)
>>>>> +{
>>>>> +    struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>>> +    struct xensnd_req *req;
>>>>> +    unsigned long flags;
>>>>> +    int ret;
>>>>> +
>>>>> +    mutex_lock(&evtchnl->u.req.req_io_lock);
>>>>> +
>>>>> +    spin_lock_irqsave(&front_info->io_lock, flags);
>>>>> +    req = be_stream_prepare_req(evtchnl, XENSND_OP_OPEN);
>>>>> +    req->op.open.pcm_format = format;
>>>>> +    req->op.open.pcm_channels = channels;
>>>>> +    req->op.open.pcm_rate = rate;
>>>>> +    req->op.open.buffer_sz = buffer_sz;
>>>>> +    req->op.open.period_sz = period_sz;
>>>>> +    req->op.open.gref_directory =
>>>>> xen_snd_front_shbuf_get_dir_start(sh_buf);
>>>>> +
>>>>> +    ret = be_stream_do_io(evtchnl);
>>>>> +    spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>>> +
>>>>> +    if (ret == 0)
>>>>> +        ret = be_stream_wait_io(evtchnl);
>>>>> +
>>>>> +    mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>>> +    return ret;
>>>>> +}
>>>>> +
>>>>> +int xen_snd_front_stream_close(struct xen_snd_front_evtchnl *evtchnl)
>>>>> +{
>>>>> +    struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>>> +    struct xensnd_req *req;
>>>>> +    unsigned long flags;
>>>>> +    int ret;
>>>>> +
>>>>> +    mutex_lock(&evtchnl->u.req.req_io_lock);
>>>>> +
>>>>> +    spin_lock_irqsave(&front_info->io_lock, flags);
>>>>> +    req = be_stream_prepare_req(evtchnl, XENSND_OP_CLOSE);
>>>>> +
>>>>> +    ret = be_stream_do_io(evtchnl);
>>>>> +    spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>>> +
>>>>> +    if (ret == 0)
>>>>> +        ret = be_stream_wait_io(evtchnl);
>>>>> +
>>>>> +    mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>>> +    return ret;
>>>>> +}
>>>>> +
>>>>> +int xen_snd_front_stream_write(struct xen_snd_front_evtchnl *evtchnl,
>>>>> +                   unsigned long pos, unsigned long count)
>>>>> +{
>>>>> +    struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>>> +    struct xensnd_req *req;
>>>>> +    unsigned long flags;
>>>>> +    int ret;
>>>>> +
>>>>> +    mutex_lock(&evtchnl->u.req.req_io_lock);
>>>>> +
>>>>> +    spin_lock_irqsave(&front_info->io_lock, flags);
>>>>> +    req = be_stream_prepare_req(evtchnl, XENSND_OP_WRITE);
>>>>> +    req->op.rw.length = count;
>>>>> +    req->op.rw.offset = pos;
>>>>> +
>>>>> +    ret = be_stream_do_io(evtchnl);
>>>>> +    spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>>> +
>>>>> +    if (ret == 0)
>>>>> +        ret = be_stream_wait_io(evtchnl);
>>>>> +
>>>>> +    mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>>> +    return ret;
>>>>> +}
>>>>> +
>>>>> +int xen_snd_front_stream_read(struct xen_snd_front_evtchnl *evtchnl,
>>>>> +                  unsigned long pos, unsigned long count)
>>>>> +{
>>>>> +    struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>>> +    struct xensnd_req *req;
>>>>> +    unsigned long flags;
>>>>> +    int ret;
>>>>> +
>>>>> +    mutex_lock(&evtchnl->u.req.req_io_lock);
>>>>> +
>>>>> +    spin_lock_irqsave(&front_info->io_lock, flags);
>>>>> +    req = be_stream_prepare_req(evtchnl, XENSND_OP_READ);
>>>>> +    req->op.rw.length = count;
>>>>> +    req->op.rw.offset = pos;
>>>>> +
>>>>> +    ret = be_stream_do_io(evtchnl);
>>>>> +    spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>>> +
>>>>> +    if (ret == 0)
>>>>> +        ret = be_stream_wait_io(evtchnl);
>>>>> +
>>>>> +    mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>>> +    return ret;
>>>>> +}
>>>>> +
>>>>> +int xen_snd_front_stream_trigger(struct xen_snd_front_evtchnl
>>>>> *evtchnl,
>>>>> +                 int type)
>>>>> +{
>>>>> +    struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>>> +    struct xensnd_req *req;
>>>>> +    unsigned long flags;
>>>>> +    int ret;
>>>>> +
>>>>> +    mutex_lock(&evtchnl->u.req.req_io_lock);
>>>>> +
>>>>> +    spin_lock_irqsave(&front_info->io_lock, flags);
>>>>> +    req = be_stream_prepare_req(evtchnl, XENSND_OP_TRIGGER);
>>>>> +    req->op.trigger.type = type;
>>>>> +
>>>>> +    ret = be_stream_do_io(evtchnl);
>>>>> +    spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>>> +
>>>>> +    if (ret == 0)
>>>>> +        ret = be_stream_wait_io(evtchnl);
>>>>> +
>>>>> +    mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>>> +    return ret;
>>>>> +}
>>>>>      static void xen_snd_drv_fini(struct xen_snd_front_info *front_info)
>>>>>    {
>>>>> +    xen_snd_front_alsa_fini(front_info);
>>>>>        xen_snd_front_evtchnl_free_all(front_info);
>>>>>    }
>>>>>    @@ -45,7 +236,7 @@ static int sndback_initwait(struct
>>>>> xen_snd_front_info *front_info)
>>>>>      static int sndback_connect(struct xen_snd_front_info *front_info)
>>>>>    {
>>>>> -    return 0;
>>>>> +    return xen_snd_front_alsa_init(front_info);
>>>>>    }
>>>>>      static void sndback_disconnect(struct xen_snd_front_info
>>>>> *front_info)
>>>>> diff --git a/sound/xen/xen_snd_front.h b/sound/xen/xen_snd_front.h
>>>>> index 9c2ffbb4e4b8..7adbdb4d2019 100644
>>>>> --- a/sound/xen/xen_snd_front.h
>>>>> +++ b/sound/xen/xen_snd_front.h
>>>>> @@ -13,17 +13,45 @@
>>>>>      #include "xen_snd_front_cfg.h"
>>>>>    +struct card_info;
>>>>> +struct xen_snd_front_evtchnl;
>>>>>    struct xen_snd_front_evtchnl_pair;
>>>>> +struct xen_snd_front_shbuf;
>>>>> +struct xensnd_query_hw_param;
>>>>>      struct xen_snd_front_info {
>>>>>        struct xenbus_device *xb_dev;
>>>>>    +    struct card_info *card_info;
>>>>> +
>>>>>        /* serializer for backend IO: request/response */
>>>>>        spinlock_t io_lock;
>>>>> +
>>>>>        int num_evt_pairs;
>>>>>        struct xen_snd_front_evtchnl_pair *evt_pairs;
>>>>>          struct xen_front_cfg_card cfg;
>>>>>    };
>>>>>    +int xen_snd_front_stream_query_hw_param(struct
>>>>> xen_snd_front_evtchnl *evtchnl,
>>>>> +                    struct xensnd_query_hw_param *hw_param_req,
>>>>> +                    struct xensnd_query_hw_param *hw_param_resp);
>>>>> +
>>>>> +int xen_snd_front_stream_prepare(struct xen_snd_front_evtchnl
>>>>> *evtchnl,
>>>>> +                 struct xen_snd_front_shbuf *sh_buf,
>>>>> +                 u8 format, unsigned int channels,
>>>>> +                 unsigned int rate, u32 buffer_sz,
>>>>> +                 u32 period_sz);
>>>>> +
>>>>> +int xen_snd_front_stream_close(struct xen_snd_front_evtchnl *evtchnl);
>>>>> +
>>>>> +int xen_snd_front_stream_write(struct xen_snd_front_evtchnl *evtchnl,
>>>>> +                   unsigned long pos, unsigned long count);
>>>>> +
>>>>> +int xen_snd_front_stream_read(struct xen_snd_front_evtchnl *evtchnl,
>>>>> +                  unsigned long pos, unsigned long count);
>>>>> +
>>>>> +int xen_snd_front_stream_trigger(struct xen_snd_front_evtchnl
>>>>> *evtchnl,
>>>>> +                 int type);
>>>>> +
>>>>>    #endif /* __XEN_SND_FRONT_H */
>>>>> diff --git a/sound/xen/xen_snd_front_alsa.c
>>>>> b/sound/xen/xen_snd_front_alsa.c
>>>>> new file mode 100644
>>>>> index 000000000000..f524b172750e
>>>>> --- /dev/null
>>>>> +++ b/sound/xen/xen_snd_front_alsa.c
>>>>> @@ -0,0 +1,830 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>>>>> +
>>>>> +/*
>>>>> + * Xen para-virtual sound device
>>>>> + *
>>>>> + * Copyright (C) 2016-2018 EPAM Systems Inc.
>>>>> + *
>>>>> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>>>> + */
>>>>> +
>>>>> +#include <linux/platform_device.h>
>>>>> +
>>>>> +#include <sound/core.h>
>>>>> +#include <sound/pcm.h>
>>>>> +#include <sound/pcm_params.h>
>>>>> +
>>>>> +#include <xen/xenbus.h>
>>>>> +
>>>>> +#include "xen_snd_front.h"
>>>>> +#include "xen_snd_front_alsa.h"
>>>>> +#include "xen_snd_front_cfg.h"
>>>>> +#include "xen_snd_front_evtchnl.h"
>>>>> +#include "xen_snd_front_shbuf.h"
>>>>> +
>>>>> +struct pcm_stream_info {
>>>> Not sure how this is generally handled in the sound drivers, but when
>>>> reviewing the code using those structures I repeatedly tried to find
>>>> their definitions in the sound headers instead of here. Same applies to
>>>> the alsa_* names.
>>>>
>>>> I'd prefer names which don't poison the name space.
>>> I'll try to do something about naming
>> One question still remains wrt alsa_* names: if this is for structures
>> I have (alsa_sndif_sample_format/alsa_sndif_hw_param), then
>> those already have sndif in their name which clearly says these are
>> Xen related ones (sndif is a Xen protocol).
>> If you also don't like the alsa_* function names then those are all
>> static and defined in this same file, so see no confusion here.
>>
>> I have changed other non-obvious struct names:
>>
>> -struct pcm_stream_info {
>> +struct xen_snd_front_pcm_stream_info {
>>
>> -struct pcm_instance_info {
>> +struct xen_snd_front_pcm_instance_info {
>>
>> -struct card_info {
>> +struct xen_snd_front_card_info {
>>
>> Does the above work for you?
> Yes, this seems to be okay.
Good, thank you
> Thanks,
>
> Juergen

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