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Message-ID: <e77fe463-68aa-b117-84c5-6dc729a3df42@gmail.com>
Date: Tue, 17 Apr 2018 14:32:06 +0300
From: Oleksandr Andrushchenko <andr2000@...il.com>
To: Juergen Gross <jgross@...e.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
Cc: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: Re: [PATCH v2 5/5] ALSA: xen-front: Implement ALSA virtual sound
driver
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
>> + struct xen_snd_front_info *front_info;
>> + struct xen_snd_front_evtchnl_pair *evt_pair;
>> + struct xen_snd_front_shbuf sh_buf;
>> + int index;
>> +
>> + bool is_open;
>> + struct snd_pcm_hardware pcm_hw;
>> +
>> + /* number of processed frames as reported by the backend */
>> + snd_pcm_uframes_t be_cur_frame;
>> + /* current HW pointer to be reported via .period callback */
>> + atomic_t hw_ptr;
>> + /* modulo of the number of processed frames - for period detection */
>> + u32 out_frames;
>> +};
>> +
>> +struct pcm_instance_info {
>> + struct card_info *card_info;
>> + struct snd_pcm *pcm;
>> + struct snd_pcm_hardware pcm_hw;
>> + int num_pcm_streams_pb;
>> + struct pcm_stream_info *streams_pb;
>> + int num_pcm_streams_cap;
>> + struct pcm_stream_info *streams_cap;
>> +};
>> +
>> +struct card_info {
>> + struct xen_snd_front_info *front_info;
>> + struct snd_card *card;
>> + struct snd_pcm_hardware pcm_hw;
>> + int num_pcm_instances;
>> + struct pcm_instance_info *pcm_instances;
>> +};
>> +
>> +struct alsa_sndif_sample_format {
>> + u8 sndif;
>> + snd_pcm_format_t alsa;
>> +};
>> +
>> +struct alsa_sndif_hw_param {
>> + u8 sndif;
>> + snd_pcm_hw_param_t alsa;
>> +};
>> +
>> +static const struct alsa_sndif_sample_format ALSA_SNDIF_FORMATS[] = {
>> + {
>> + .sndif = XENSND_PCM_FORMAT_U8,
>> + .alsa = SNDRV_PCM_FORMAT_U8
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_S8,
>> + .alsa = SNDRV_PCM_FORMAT_S8
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_U16_LE,
>> + .alsa = SNDRV_PCM_FORMAT_U16_LE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_U16_BE,
>> + .alsa = SNDRV_PCM_FORMAT_U16_BE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_S16_LE,
>> + .alsa = SNDRV_PCM_FORMAT_S16_LE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_S16_BE,
>> + .alsa = SNDRV_PCM_FORMAT_S16_BE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_U24_LE,
>> + .alsa = SNDRV_PCM_FORMAT_U24_LE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_U24_BE,
>> + .alsa = SNDRV_PCM_FORMAT_U24_BE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_S24_LE,
>> + .alsa = SNDRV_PCM_FORMAT_S24_LE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_S24_BE,
>> + .alsa = SNDRV_PCM_FORMAT_S24_BE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_U32_LE,
>> + .alsa = SNDRV_PCM_FORMAT_U32_LE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_U32_BE,
>> + .alsa = SNDRV_PCM_FORMAT_U32_BE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_S32_LE,
>> + .alsa = SNDRV_PCM_FORMAT_S32_LE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_S32_BE,
>> + .alsa = SNDRV_PCM_FORMAT_S32_BE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_A_LAW,
>> + .alsa = SNDRV_PCM_FORMAT_A_LAW
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_MU_LAW,
>> + .alsa = SNDRV_PCM_FORMAT_MU_LAW
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_F32_LE,
>> + .alsa = SNDRV_PCM_FORMAT_FLOAT_LE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_F32_BE,
>> + .alsa = SNDRV_PCM_FORMAT_FLOAT_BE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_F64_LE,
>> + .alsa = SNDRV_PCM_FORMAT_FLOAT64_LE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_F64_BE,
>> + .alsa = SNDRV_PCM_FORMAT_FLOAT64_BE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_IEC958_SUBFRAME_LE,
>> + .alsa = SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_IEC958_SUBFRAME_BE,
>> + .alsa = SNDRV_PCM_FORMAT_IEC958_SUBFRAME_BE
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_IMA_ADPCM,
>> + .alsa = SNDRV_PCM_FORMAT_IMA_ADPCM
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_MPEG,
>> + .alsa = SNDRV_PCM_FORMAT_MPEG
>> + },
>> + {
>> + .sndif = XENSND_PCM_FORMAT_GSM,
>> + .alsa = SNDRV_PCM_FORMAT_GSM
>> + },
>> +};
>> +
>> +static int to_sndif_format(snd_pcm_format_t format)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < ARRAY_SIZE(ALSA_SNDIF_FORMATS); i++)
>> + if (ALSA_SNDIF_FORMATS[i].alsa == format)
>> + return ALSA_SNDIF_FORMATS[i].sndif;
>> +
>> + return -EINVAL;
>> +}
>> +
>> +static u64 to_sndif_formats_mask(u64 alsa_formats)
>> +{
>> + u64 mask;
>> + int i;
>> +
>> + mask = 0;
>> + for (i = 0; i < ARRAY_SIZE(ALSA_SNDIF_FORMATS); i++)
>> + if (1 << ALSA_SNDIF_FORMATS[i].alsa & alsa_formats)
>> + mask |= 1 << ALSA_SNDIF_FORMATS[i].sndif;
>> +
>> + return mask;
>> +}
>> +
>> +static u64 to_alsa_formats_mask(u64 sndif_formats)
>> +{
>> + u64 mask;
>> + int i;
>> +
>> + mask = 0;
>> + for (i = 0; i < ARRAY_SIZE(ALSA_SNDIF_FORMATS); i++)
>> + if (1 << ALSA_SNDIF_FORMATS[i].sndif & sndif_formats)
>> + mask |= 1 << ALSA_SNDIF_FORMATS[i].alsa;
>> +
>> + return mask;
>> +}
>> +
>> +static void stream_clear(struct pcm_stream_info *stream)
>> +{
>> + stream->is_open = false;
>> + stream->be_cur_frame = 0;
>> + stream->out_frames = 0;
>> + atomic_set(&stream->hw_ptr, 0);
>> + xen_snd_front_evtchnl_pair_clear(stream->evt_pair);
>> + xen_snd_front_shbuf_clear(&stream->sh_buf);
>> +}
>> +
>> +static void stream_free(struct pcm_stream_info *stream)
>> +{
>> + xen_snd_front_shbuf_free(&stream->sh_buf);
>> + stream_clear(stream);
>> +}
>> +
>> +static struct pcm_stream_info *stream_get(struct snd_pcm_substream *substream)
>> +{
>> + struct pcm_instance_info *pcm_instance =
>> + snd_pcm_substream_chip(substream);
>> + struct pcm_stream_info *stream;
>> +
>> + if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
>> + stream = &pcm_instance->streams_pb[substream->number];
>> + else
>> + stream = &pcm_instance->streams_cap[substream->number];
>> +
>> + return stream;
>> +}
>> +
>> +static int alsa_hw_rule(struct snd_pcm_hw_params *params,
>> + struct snd_pcm_hw_rule *rule)
>> +{
>> + struct pcm_stream_info *stream = rule->private;
>> + struct device *dev = &stream->front_info->xb_dev->dev;
>> + struct snd_mask *formats =
>> + hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
>> + struct snd_interval *rates =
>> + hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
>> + struct snd_interval *channels =
>> + hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
>> + struct snd_interval *period =
>> + hw_param_interval(params,
>> + SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
>> + struct snd_interval *buffer =
>> + hw_param_interval(params,
>> + SNDRV_PCM_HW_PARAM_BUFFER_SIZE);
>> + struct xensnd_query_hw_param req;
>> + struct xensnd_query_hw_param resp;
>> + struct snd_interval interval;
>> + struct snd_mask mask;
>> + u64 sndif_formats;
>> + int changed, ret;
>> +
>> + /* collect all the values we need for the query */
>> +
>> + req.formats = to_sndif_formats_mask((u64)formats->bits[0] |
>> + (u64)(formats->bits[1]) << 32);
>> +
>> + req.rates.min = rates->min;
>> + req.rates.max = rates->max;
>> +
>> + req.channels.min = channels->min;
>> + req.channels.max = channels->max;
>> +
>> + req.buffer.min = buffer->min;
>> + req.buffer.max = buffer->max;
>> +
>> + req.period.min = period->min;
>> + req.period.max = period->max;
>> +
>> + ret = xen_snd_front_stream_query_hw_param(&stream->evt_pair->req,
>> + &req, &resp);
>> + if (ret < 0) {
>> + /* check if this is due to backend communication error */
>> + if (ret == -EIO || ret == -ETIMEDOUT)
>> + dev_err(dev, "Failed to query ALSA HW parameters\n");
>> + return ret;
>> + }
>> +
>> + /* refine HW parameters after the query */
>> + changed = 0;
>> +
>> + sndif_formats = to_alsa_formats_mask(resp.formats);
>> + snd_mask_none(&mask);
>> + mask.bits[0] = (u32)sndif_formats;
>> + mask.bits[1] = (u32)(sndif_formats >> 32);
>> + ret = snd_mask_refine(formats, &mask);
>> + if (ret < 0)
>> + return ret;
>> + changed |= ret;
>> +
>> + interval.openmin = 0;
>> + interval.openmax = 0;
>> + interval.integer = 1;
>> +
>> + interval.min = resp.rates.min;
>> + interval.max = resp.rates.max;
>> + ret = snd_interval_refine(rates, &interval);
>> + if (ret < 0)
>> + return ret;
>> + changed |= ret;
>> +
>> + interval.min = resp.channels.min;
>> + interval.max = resp.channels.max;
>> + ret = snd_interval_refine(channels, &interval);
>> + if (ret < 0)
>> + return ret;
>> + changed |= ret;
>> +
>> + interval.min = resp.buffer.min;
>> + interval.max = resp.buffer.max;
>> + ret = snd_interval_refine(buffer, &interval);
>> + if (ret < 0)
>> + return ret;
>> + changed |= ret;
>> +
>> + interval.min = resp.period.min;
>> + interval.max = resp.period.max;
>> + ret = snd_interval_refine(period, &interval);
>> + if (ret < 0)
>> + return ret;
>> + changed |= ret;
>> +
>> + return changed;
>> +}
>> +
>> +static int alsa_open(struct snd_pcm_substream *substream)
>> +{
>> + struct pcm_instance_info *pcm_instance =
>> + snd_pcm_substream_chip(substream);
>> + struct pcm_stream_info *stream = stream_get(substream);
>> + struct snd_pcm_runtime *runtime = substream->runtime;
>> + struct xen_snd_front_info *front_info =
>> + pcm_instance->card_info->front_info;
>> + struct device *dev = &front_info->xb_dev->dev;
>> + unsigned long flags;
>> + int ret;
>> +
>> + /*
>> + * return our HW properties: override defaults with those configured
>> + * via XenStore
>> + */
>> + runtime->hw = stream->pcm_hw;
>> + runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP |
>> + SNDRV_PCM_INFO_MMAP_VALID |
>> + SNDRV_PCM_INFO_DOUBLE |
>> + SNDRV_PCM_INFO_BATCH |
>> + SNDRV_PCM_INFO_NONINTERLEAVED |
>> + SNDRV_PCM_INFO_RESUME |
>> + SNDRV_PCM_INFO_PAUSE);
>> + runtime->hw.info |= SNDRV_PCM_INFO_INTERLEAVED;
>> +
>> + spin_lock_irqsave(&front_info->io_lock, flags);
>> +
>> + stream->evt_pair = &front_info->evt_pairs[stream->index];
>> +
>> + stream->front_info = front_info;
>> +
>> + xen_snd_front_evtchnl_pair_set_connected(stream->evt_pair, true);
>> +
>> + stream->evt_pair->evt.u.evt.substream = substream;
>> +
>> + stream_clear(stream);
>> +
>> + spin_unlock_irqrestore(&front_info->io_lock, flags);
>> +
>> + ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_FORMAT,
>> + alsa_hw_rule, stream,
>> + SNDRV_PCM_HW_PARAM_FORMAT, -1);
>> + if (ret) {
>> + dev_err(dev, "Failed to add HW rule for SNDRV_PCM_HW_PARAM_FORMAT\n");
>> + return ret;
>> + }
>> +
>> + ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
>> + alsa_hw_rule, stream,
>> + SNDRV_PCM_HW_PARAM_RATE, -1);
>> + if (ret) {
>> + dev_err(dev, "Failed to add HW rule for SNDRV_PCM_HW_PARAM_RATE\n");
>> + return ret;
>> + }
>> +
>> + ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
>> + alsa_hw_rule, stream,
>> + SNDRV_PCM_HW_PARAM_CHANNELS, -1);
>> + if (ret) {
>> + dev_err(dev, "Failed to add HW rule for SNDRV_PCM_HW_PARAM_CHANNELS\n");
>> + return ret;
>> + }
>> +
>> + ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
>> + alsa_hw_rule, stream,
>> + SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1);
>> + if (ret) {
>> + dev_err(dev, "Failed to add HW rule for SNDRV_PCM_HW_PARAM_PERIOD_SIZE\n");
>> + return ret;
>> + }
>> +
>> + ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
>> + alsa_hw_rule, stream,
>> + SNDRV_PCM_HW_PARAM_BUFFER_SIZE, -1);
>> + if (ret) {
>> + dev_err(dev, "Failed to add HW rule for SNDRV_PCM_HW_PARAM_BUFFER_SIZE\n");
>> + return ret;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int alsa_close(struct snd_pcm_substream *substream)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&stream->front_info->io_lock, flags);
>> +
>> + xen_snd_front_evtchnl_pair_set_connected(stream->evt_pair, false);
>> +
>> + spin_unlock_irqrestore(&stream->front_info->io_lock, flags);
>> + return 0;
>> +}
>> +
>> +static int alsa_hw_params(struct snd_pcm_substream *substream,
>> + struct snd_pcm_hw_params *params)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> + int ret;
>> +
>> + /*
>> + * this callback may be called multiple times,
>> + * so free the previously allocated shared buffer if any
>> + */
>> + stream_free(stream);
>> +
>> + ret = xen_snd_front_shbuf_alloc(stream->front_info->xb_dev,
>> + &stream->sh_buf,
>> + params_buffer_bytes(params));
>> + if (ret < 0) {
>> + stream_free(stream);
>> + dev_err(&stream->front_info->xb_dev->dev,
>> + "Failed to allocate buffers for stream with index %d\n",
>> + stream->index);
>> + return ret;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int alsa_hw_free(struct snd_pcm_substream *substream)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> + int ret;
>> +
>> + ret = xen_snd_front_stream_close(&stream->evt_pair->req);
>> + stream_free(stream);
>> + return ret;
>> +}
>> +
>> +static int alsa_prepare(struct snd_pcm_substream *substream)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> +
>> + if (!stream->is_open) {
>> + struct snd_pcm_runtime *runtime = substream->runtime;
>> + u8 sndif_format;
>> + int ret;
>> +
>> + sndif_format = to_sndif_format(runtime->format);
>> + if (sndif_format < 0) {
>> + dev_err(&stream->front_info->xb_dev->dev,
>> + "Unsupported sample format: %d\n",
>> + runtime->format);
>> + return sndif_format;
>> + }
>> +
>> + ret = xen_snd_front_stream_prepare(&stream->evt_pair->req,
>> + &stream->sh_buf,
>> + sndif_format,
>> + runtime->channels,
>> + runtime->rate,
>> + snd_pcm_lib_buffer_bytes(substream),
>> + snd_pcm_lib_period_bytes(substream));
>> + if (ret < 0)
>> + return ret;
>> +
>> + stream->is_open = true;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int alsa_trigger(struct snd_pcm_substream *substream, int cmd)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> + int type;
>> +
>> + switch (cmd) {
>> + case SNDRV_PCM_TRIGGER_START:
>> + type = XENSND_OP_TRIGGER_START;
>> + break;
>> +
>> + case SNDRV_PCM_TRIGGER_RESUME:
>> + type = XENSND_OP_TRIGGER_RESUME;
>> + break;
>> +
>> + case SNDRV_PCM_TRIGGER_STOP:
>> + type = XENSND_OP_TRIGGER_STOP;
>> + break;
>> +
>> + case SNDRV_PCM_TRIGGER_SUSPEND:
>> + type = XENSND_OP_TRIGGER_PAUSE;
>> + break;
>> +
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + return xen_snd_front_stream_trigger(&stream->evt_pair->req, type);
>> +}
>> +
>> +void xen_snd_front_alsa_handle_cur_pos(struct xen_snd_front_evtchnl *evtchnl,
>> + u64 pos_bytes)
>> +{
>> + struct snd_pcm_substream *substream = evtchnl->u.evt.substream;
>> + struct pcm_stream_info *stream = stream_get(substream);
>> + snd_pcm_uframes_t delta, new_hw_ptr, cur_frame;
>> +
>> + cur_frame = bytes_to_frames(substream->runtime, pos_bytes);
>> +
>> + delta = cur_frame - stream->be_cur_frame;
>> + stream->be_cur_frame = cur_frame;
>> +
>> + new_hw_ptr = (snd_pcm_uframes_t)atomic_read(&stream->hw_ptr);
>> + new_hw_ptr = (new_hw_ptr + delta) % substream->runtime->buffer_size;
>> + atomic_set(&stream->hw_ptr, (int)new_hw_ptr);
>> +
>> + stream->out_frames += delta;
>> + if (stream->out_frames > substream->runtime->period_size) {
>> + stream->out_frames %= substream->runtime->period_size;
>> + snd_pcm_period_elapsed(substream);
>> + }
>> +}
>> +
>> +static snd_pcm_uframes_t alsa_pointer(struct snd_pcm_substream *substream)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> +
>> + return (snd_pcm_uframes_t)atomic_read(&stream->hw_ptr);
>> +}
>> +
>> +static int alsa_pb_copy_user(struct snd_pcm_substream *substream,
>> + int channel, unsigned long pos, void __user *src,
>> + unsigned long count)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> +
>> + if (unlikely(pos + count > stream->sh_buf.buffer_sz))
>> + return -EINVAL;
>> +
>> + if (copy_from_user(stream->sh_buf.buffer + pos, src, count))
>> + return -EFAULT;
>> +
>> + return xen_snd_front_stream_write(&stream->evt_pair->req, pos, count);
>> +}
>> +
>> +static int alsa_pb_copy_kernel(struct snd_pcm_substream *substream,
>> + int channel, unsigned long pos, void *src,
>> + unsigned long count)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> +
>> + if (unlikely(pos + count > stream->sh_buf.buffer_sz))
>> + return -EINVAL;
>> +
>> + memcpy(stream->sh_buf.buffer + pos, src, count);
>> +
>> + return xen_snd_front_stream_write(&stream->evt_pair->req, pos, count);
>> +}
>> +
>> +static int alsa_cap_copy_user(struct snd_pcm_substream *substream,
>> + int channel, unsigned long pos, void __user *dst,
>> + unsigned long count)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> + int ret;
>> +
>> + if (unlikely(pos + count > stream->sh_buf.buffer_sz))
>> + return -EINVAL;
>> +
>> + ret = xen_snd_front_stream_read(&stream->evt_pair->req, pos, count);
>> + if (ret < 0)
>> + return ret;
>> +
>> + return copy_to_user(dst, stream->sh_buf.buffer + pos, count) ?
>> + -EFAULT : 0;
>> +}
>> +
>> +static int alsa_cap_copy_kernel(struct snd_pcm_substream *substream,
>> + int channel, unsigned long pos, void *dst,
>> + unsigned long count)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> + int ret;
>> +
>> + if (unlikely(pos + count > stream->sh_buf.buffer_sz))
>> + return -EINVAL;
>> +
>> + ret = xen_snd_front_stream_read(&stream->evt_pair->req, pos, count);
>> + if (ret < 0)
>> + return ret;
>> +
>> + memcpy(dst, stream->sh_buf.buffer + pos, count);
>> +
>> + return 0;
>> +}
>> +
>> +static int alsa_pb_fill_silence(struct snd_pcm_substream *substream,
>> + int channel, unsigned long pos,
>> + unsigned long count)
>> +{
>> + struct pcm_stream_info *stream = stream_get(substream);
>> +
>> + if (unlikely(pos + count > stream->sh_buf.buffer_sz))
>> + return -EINVAL;
>> +
>> + memset(stream->sh_buf.buffer + pos, 0, count);
>> +
>> + return xen_snd_front_stream_write(&stream->evt_pair->req, pos, count);
>> +}
>> +
>> +/*
>> + * FIXME: The mmaped data transfer is asynchronous and there is no
>> + * ack signal from user-space when it is done. This is the
>> + * reason it is not implemented in the PV driver as we do need
>> + * to know when the buffer can be transferred to the backend.
>> + */
>> +
>> +static struct snd_pcm_ops snd_drv_alsa_playback_ops = {
>> + .open = alsa_open,
>> + .close = alsa_close,
>> + .ioctl = snd_pcm_lib_ioctl,
>> + .hw_params = alsa_hw_params,
>> + .hw_free = alsa_hw_free,
>> + .prepare = alsa_prepare,
>> + .trigger = alsa_trigger,
>> + .pointer = alsa_pointer,
>> + .copy_user = alsa_pb_copy_user,
>> + .copy_kernel = alsa_pb_copy_kernel,
>> + .fill_silence = alsa_pb_fill_silence,
>> +};
>> +
>> +static struct snd_pcm_ops snd_drv_alsa_capture_ops = {
>> + .open = alsa_open,
>> + .close = alsa_close,
>> + .ioctl = snd_pcm_lib_ioctl,
>> + .hw_params = alsa_hw_params,
>> + .hw_free = alsa_hw_free,
>> + .prepare = alsa_prepare,
>> + .trigger = alsa_trigger,
>> + .pointer = alsa_pointer,
>> + .copy_user = alsa_cap_copy_user,
>> + .copy_kernel = alsa_cap_copy_kernel,
>> +};
>> +
>> +static int new_pcm_instance(struct card_info *card_info,
>> + struct xen_front_cfg_pcm_instance *instance_cfg,
>> + struct pcm_instance_info *pcm_instance_info)
>> +{
>> + struct snd_pcm *pcm;
>> + int ret, i;
>> +
>> + dev_dbg(&card_info->front_info->xb_dev->dev,
>> + "New PCM device \"%s\" with id %d playback %d capture %d",
>> + instance_cfg->name,
>> + instance_cfg->device_id,
>> + instance_cfg->num_streams_pb,
>> + instance_cfg->num_streams_cap);
>> +
>> + pcm_instance_info->card_info = card_info;
>> +
>> + pcm_instance_info->pcm_hw = instance_cfg->pcm_hw;
>> +
>> + if (instance_cfg->num_streams_pb) {
>> + pcm_instance_info->streams_pb =
>> + devm_kcalloc(&card_info->card->card_dev,
>> + instance_cfg->num_streams_pb,
>> + sizeof(struct pcm_stream_info),
>> + GFP_KERNEL);
>> + if (!pcm_instance_info->streams_pb)
>> + return -ENOMEM;
>> + }
>> +
>> + if (instance_cfg->num_streams_cap) {
>> + pcm_instance_info->streams_cap =
>> + devm_kcalloc(&card_info->card->card_dev,
>> + instance_cfg->num_streams_cap,
>> + sizeof(struct pcm_stream_info),
>> + GFP_KERNEL);
>> + if (!pcm_instance_info->streams_cap)
>> + return -ENOMEM;
>> + }
>> +
>> + pcm_instance_info->num_pcm_streams_pb =
>> + instance_cfg->num_streams_pb;
>> + pcm_instance_info->num_pcm_streams_cap =
>> + instance_cfg->num_streams_cap;
>> +
>> + for (i = 0; i < pcm_instance_info->num_pcm_streams_pb; i++) {
>> + pcm_instance_info->streams_pb[i].pcm_hw =
>> + instance_cfg->streams_pb[i].pcm_hw;
>> + pcm_instance_info->streams_pb[i].index =
>> + instance_cfg->streams_pb[i].index;
>> + }
>> +
>> + for (i = 0; i < pcm_instance_info->num_pcm_streams_cap; i++) {
>> + pcm_instance_info->streams_cap[i].pcm_hw =
>> + instance_cfg->streams_cap[i].pcm_hw;
>> + pcm_instance_info->streams_cap[i].index =
>> + instance_cfg->streams_cap[i].index;
>> + }
>> +
>> + ret = snd_pcm_new(card_info->card, instance_cfg->name,
>> + instance_cfg->device_id,
>> + instance_cfg->num_streams_pb,
>> + instance_cfg->num_streams_cap,
>> + &pcm);
>> + if (ret < 0)
>> + return ret;
>> +
>> + pcm->private_data = pcm_instance_info;
>> + pcm->info_flags = 0;
>> + /* we want to handle all PCM operations in non-atomic context */
>> + pcm->nonatomic = true;
>> + strncpy(pcm->name, "Virtual card PCM", sizeof(pcm->name));
>> +
>> + if (instance_cfg->num_streams_pb)
>> + snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK,
>> + &snd_drv_alsa_playback_ops);
>> +
>> + if (instance_cfg->num_streams_cap)
>> + snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE,
>> + &snd_drv_alsa_capture_ops);
>> +
>> + pcm_instance_info->pcm = pcm;
>> + return 0;
>> +}
>> +
>> +int xen_snd_front_alsa_init(struct xen_snd_front_info *front_info)
>> +{
>> + struct device *dev = &front_info->xb_dev->dev;
>> + struct xen_front_cfg_card *cfg = &front_info->cfg;
>> + struct card_info *card_info;
>> + struct snd_card *card;
>> + int ret, i;
>> +
>> + dev_dbg(dev, "Creating virtual sound card\n");
>> +
>> + ret = snd_card_new(dev, 0, XENSND_DRIVER_NAME, THIS_MODULE,
>> + sizeof(struct card_info), &card);
>> + if (ret < 0)
>> + return ret;
>> +
>> + card_info = card->private_data;
>> + card_info->front_info = front_info;
>> + front_info->card_info = card_info;
>> + card_info->card = card;
>> + card_info->pcm_instances =
>> + devm_kcalloc(dev, cfg->num_pcm_instances,
>> + sizeof(struct pcm_instance_info),
>> + GFP_KERNEL);
>> + if (!card_info->pcm_instances) {
>> + ret = -ENOMEM;
>> + goto fail;
>> + }
>> +
>> + card_info->num_pcm_instances = cfg->num_pcm_instances;
>> + card_info->pcm_hw = cfg->pcm_hw;
>> +
>> + for (i = 0; i < cfg->num_pcm_instances; i++) {
>> + ret = new_pcm_instance(card_info, &cfg->pcm_instances[i],
>> + &card_info->pcm_instances[i]);
>> + if (ret < 0)
>> + goto fail;
>> + }
>> +
>> + strncpy(card->driver, XENSND_DRIVER_NAME, sizeof(card->driver));
>> + strncpy(card->shortname, cfg->name_short, sizeof(card->shortname));
>> + strncpy(card->longname, cfg->name_long, sizeof(card->longname));
>> +
>> + ret = snd_card_register(card);
>> + if (ret < 0)
>> + goto fail;
>> +
>> + return 0;
>> +
>> +fail:
>> + snd_card_free(card);
>> + return ret;
>> +}
>> +
>> +void xen_snd_front_alsa_fini(struct xen_snd_front_info *front_info)
>> +{
>> + struct card_info *card_info;
>> + struct snd_card *card;
>> +
>> + card_info = front_info->card_info;
>> + if (!card_info)
>> + return;
>> +
>> + card = card_info->card;
>> + if (!card)
>> + return;
>> +
>> + dev_dbg(&front_info->xb_dev->dev, "Removing virtual sound card %d\n",
>> + card->number);
>> + snd_card_free(card);
>> +
>> + /* card_info will be freed when destroying front_info->xb_dev->dev */
>> + card_info->card = NULL;
>> +}
>> diff --git a/sound/xen/xen_snd_front_alsa.h b/sound/xen/xen_snd_front_alsa.h
>> new file mode 100644
>> index 000000000000..18abd9eec967
>> --- /dev/null
>> +++ b/sound/xen/xen_snd_front_alsa.h
>> @@ -0,0 +1,23 @@
>> +/* 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>
>> + */
>> +
>> +#ifndef __XEN_SND_FRONT_ALSA_H
>> +#define __XEN_SND_FRONT_ALSA_H
>> +
>> +struct xen_snd_front_info;
>> +
>> +int xen_snd_front_alsa_init(struct xen_snd_front_info *front_info);
>> +
>> +void xen_snd_front_alsa_fini(struct xen_snd_front_info *front_info);
>> +
>> +void xen_snd_front_alsa_handle_cur_pos(struct xen_snd_front_evtchnl *evtchnl,
>> + u64 pos_bytes);
>> +
>> +#endif /* __XEN_SND_FRONT_ALSA_H */
>> diff --git a/sound/xen/xen_snd_front_evtchnl.c b/sound/xen/xen_snd_front_evtchnl.c
>> index 9ece39f938f8..470196518716 100644
>> --- a/sound/xen/xen_snd_front_evtchnl.c
>> +++ b/sound/xen/xen_snd_front_evtchnl.c
>> @@ -14,6 +14,7 @@
>> #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"
>>
>> @@ -111,7 +112,10 @@ static irqreturn_t evtchnl_interrupt_evt(int irq, void *dev_id)
>>
>> switch (event->type) {
>> case XENSND_EVT_CUR_POS:
>> - /* do nothing at the moment */
>> + spin_unlock_irqrestore(&front_info->io_lock, flags);
>> + xen_snd_front_alsa_handle_cur_pos(channel,
>> + event->op.cur_pos.position);
>> + spin_lock_irqsave(&front_info->io_lock, flags);
> Is this correct? Why can you free the lock here without doing any
> harm? What is the lock protecting? I'd like to see at least some
> comments explaining why the lock is needed and why it can be dropped
> here.
Well, this code has issues and will be re-worked:
1. Which locks I need:
1.1. lock to serialize requests to backend
1.2. lock to protect the ring: between requests code and interrupt handler
2. I don't really need a spinlock here b/c interrupts are threaded,
so I can safely use a mutex: thus no need for fancy code with unlocking
and locking again while servicing xen_snd_front_alsa_handle_cur_pos
Thank you
>
> Juergen
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