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Message-ID: <61b9fe09-84c7-f109-3242-167bc324844e@opensynergy.com>
Date: Sun, 24 Jan 2021 17:51:23 +0100
From: Anton Yakovlev <anton.yakovlev@...nsynergy.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
CC: <virtualization@...ts.linux-foundation.org>,
<alsa-devel@...a-project.org>, <virtio-dev@...ts.oasis-open.org>,
<linux-kernel@...r.kernel.org>, Takashi Iwai <tiwai@...e.com>
Subject: Re: [PATCH 5/7] ALSA: virtio: PCM substream operators
On 20.01.2021 09:36, Michael S. Tsirkin wrote:
> CAUTION: This email originated from outside of the organization.
> Do not click links or open attachments unless you recognize the sender and know the content is safe.
>
>
> On Wed, Jan 20, 2021 at 01:36:33AM +0100, Anton Yakovlev wrote:
>> Introduce the operators required for the operation of substreams.
>>
>> Signed-off-by: Anton Yakovlev <anton.yakovlev@...nsynergy.com>
>> ---
>> sound/virtio/Makefile | 3 +-
>> sound/virtio/virtio_pcm.c | 5 +-
>> sound/virtio/virtio_pcm.h | 2 +
>> sound/virtio/virtio_pcm_ops.c | 509 ++++++++++++++++++++++++++++++++++
>> 4 files changed, 517 insertions(+), 2 deletions(-)
>> create mode 100644 sound/virtio/virtio_pcm_ops.c
>>
>> diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
>> index 626af3cc3ed7..34493226793f 100644
>> --- a/sound/virtio/Makefile
>> +++ b/sound/virtio/Makefile
>> @@ -6,5 +6,6 @@ virtio_snd-objs := \
>> virtio_card.o \
>> virtio_ctl_msg.o \
>> virtio_pcm.o \
>> - virtio_pcm_msg.o
>> + virtio_pcm_msg.o \
>> + virtio_pcm_ops.o
>>
>> diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c
>> index 1ab50dcc88c8..6a1ca6b2c3ca 100644
>> --- a/sound/virtio/virtio_pcm.c
>> +++ b/sound/virtio/virtio_pcm.c
>> @@ -121,7 +121,8 @@ static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *substream,
>> SNDRV_PCM_INFO_MMAP_VALID |
>> SNDRV_PCM_INFO_BATCH |
>> SNDRV_PCM_INFO_BLOCK_TRANSFER |
>> - SNDRV_PCM_INFO_INTERLEAVED;
>> + SNDRV_PCM_INFO_INTERLEAVED |
>> + SNDRV_PCM_INFO_PAUSE;
>>
>> if (!info->channels_min || info->channels_min > info->channels_max) {
>> dev_err(&vdev->dev,
>> @@ -503,6 +504,8 @@ int virtsnd_pcm_build_devs(struct virtio_snd *snd)
>> if (rc)
>> return rc;
>> }
>> +
>> + snd_pcm_set_ops(pcm->pcm, i, &virtsnd_pcm_ops);
>> }
>>
>> return 0;
>> diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h
>> index d011b7e1d18d..fe467bc05d8b 100644
>> --- a/sound/virtio/virtio_pcm.h
>> +++ b/sound/virtio/virtio_pcm.h
>> @@ -90,6 +90,8 @@ struct virtio_pcm {
>> struct virtio_pcm_stream streams[SNDRV_PCM_STREAM_LAST + 1];
>> };
>>
>> +extern const struct snd_pcm_ops virtsnd_pcm_ops;
>> +
>> int virtsnd_pcm_validate(struct virtio_device *vdev);
>>
>> int virtsnd_pcm_parse_cfg(struct virtio_snd *snd);
>> diff --git a/sound/virtio/virtio_pcm_ops.c b/sound/virtio/virtio_pcm_ops.c
>> new file mode 100644
>> index 000000000000..8d26c1144ad6
>> --- /dev/null
>> +++ b/sound/virtio/virtio_pcm_ops.c
>> @@ -0,0 +1,509 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Sound card driver for virtio
>> + * Copyright (C) 2020 OpenSynergy GmbH
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
>> + */
>> +#include <sound/pcm_params.h>
>> +
>> +#include "virtio_card.h"
>> +
>> +/*
>> + * Our main concern here is maintaining the correct state of the underlying I/O
>> + * virtqueues. Thus, operators are implemented to support all of the following
>> + * possible control paths (excluding all trivial ones):
>> + *
>> + * +---------+
>> + * | open() |<------------------+
>> + * +----+----+ |
>> + * v |
>> + * +------+------+ |
>> + * +------------->| hw_params() |<-------------+ |
>> + * | +-------------+ | |
>> + * | v | |
>> + * | +-----------+ | |
>> + * | | prepare() |<-----------+ | |
>> + * | +-----------+ | | |
>> + * | v | | |
>> + * | +-------------------------+ | | |
>> + * +-----------+ | trigger(START/ | | | |
>> + * | restore() | | PAUSE_RELEASE/ |<-+ | | |
>> + * +-----------+ | RESUME) | | | | |
>> + * ^ +-------------------------+ | | | |
>> + * | v | | | |
>> + * | +-----------+ | | | |
>> + * | | pointer() | | | | |
>> + * | +-----------+ | | | |
>> + * | v | | | |
>> + * | +---------------------+ | | | |
>> + * +-----------+ | trigger(STOP/ |----+ | | |
>> + * | freeze() |<---| PAUSE_PUSH/ |-------+ | |
>> + * +-----------+ | SUSPEND) | | |
>> + * +---------------------+ | |
>> + * v | |
>> + * +-----------+ | |
>> + * | hw_free() |---------------+ |
>> + * +-----------+ |
>> + * v |
>> + * +---------+ |
>> + * | close() |-------------------+
>> + * +---------+
>> + */
>> +
>> +/* Map for converting ALSA format to VirtIO format. */
>> +struct virtsnd_a2v_format {
>> + unsigned int alsa_bit;
>> + unsigned int vio_bit;
>> +};
>> +
>> +static const struct virtsnd_a2v_format g_a2v_format_map[] = {
>> + { SNDRV_PCM_FORMAT_IMA_ADPCM, VIRTIO_SND_PCM_FMT_IMA_ADPCM },
>> + { SNDRV_PCM_FORMAT_MU_LAW, VIRTIO_SND_PCM_FMT_MU_LAW },
>> + { SNDRV_PCM_FORMAT_A_LAW, VIRTIO_SND_PCM_FMT_A_LAW },
>> + { SNDRV_PCM_FORMAT_S8, VIRTIO_SND_PCM_FMT_S8 },
>> + { SNDRV_PCM_FORMAT_U8, VIRTIO_SND_PCM_FMT_U8 },
>> + { SNDRV_PCM_FORMAT_S16_LE, VIRTIO_SND_PCM_FMT_S16 },
>> + { SNDRV_PCM_FORMAT_U16_LE, VIRTIO_SND_PCM_FMT_U16 },
>> + { SNDRV_PCM_FORMAT_S18_3LE, VIRTIO_SND_PCM_FMT_S18_3 },
>> + { SNDRV_PCM_FORMAT_U18_3LE, VIRTIO_SND_PCM_FMT_U18_3 },
>> + { SNDRV_PCM_FORMAT_S20_3LE, VIRTIO_SND_PCM_FMT_S20_3 },
>> + { SNDRV_PCM_FORMAT_U20_3LE, VIRTIO_SND_PCM_FMT_U20_3 },
>> + { SNDRV_PCM_FORMAT_S24_3LE, VIRTIO_SND_PCM_FMT_S24_3 },
>> + { SNDRV_PCM_FORMAT_U24_3LE, VIRTIO_SND_PCM_FMT_U24_3 },
>> + { SNDRV_PCM_FORMAT_S20_LE, VIRTIO_SND_PCM_FMT_S20 },
>> + { SNDRV_PCM_FORMAT_U20_LE, VIRTIO_SND_PCM_FMT_U20 },
>> + { SNDRV_PCM_FORMAT_S24_LE, VIRTIO_SND_PCM_FMT_S24 },
>> + { SNDRV_PCM_FORMAT_U24_LE, VIRTIO_SND_PCM_FMT_U24 },
>> + { SNDRV_PCM_FORMAT_S32_LE, VIRTIO_SND_PCM_FMT_S32 },
>> + { SNDRV_PCM_FORMAT_U32_LE, VIRTIO_SND_PCM_FMT_U32 },
>> + { SNDRV_PCM_FORMAT_FLOAT_LE, VIRTIO_SND_PCM_FMT_FLOAT },
>> + { SNDRV_PCM_FORMAT_FLOAT64_LE, VIRTIO_SND_PCM_FMT_FLOAT64 },
>> + { SNDRV_PCM_FORMAT_DSD_U8, VIRTIO_SND_PCM_FMT_DSD_U8 },
>> + { SNDRV_PCM_FORMAT_DSD_U16_LE, VIRTIO_SND_PCM_FMT_DSD_U16 },
>> + { SNDRV_PCM_FORMAT_DSD_U32_LE, VIRTIO_SND_PCM_FMT_DSD_U32 },
>> + { SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE,
>> + VIRTIO_SND_PCM_FMT_IEC958_SUBFRAME }
>> +};
>> +
>> +/* Map for converting ALSA frame rate to VirtIO frame rate. */
>> +struct virtsnd_a2v_rate {
>> + unsigned int rate;
>> + unsigned int vio_bit;
>> +};
>> +
>> +static const struct virtsnd_a2v_rate g_a2v_rate_map[] = {
>> + { 5512, VIRTIO_SND_PCM_RATE_5512 },
>> + { 8000, VIRTIO_SND_PCM_RATE_8000 },
>> + { 11025, VIRTIO_SND_PCM_RATE_11025 },
>> + { 16000, VIRTIO_SND_PCM_RATE_16000 },
>> + { 22050, VIRTIO_SND_PCM_RATE_22050 },
>> + { 32000, VIRTIO_SND_PCM_RATE_32000 },
>> + { 44100, VIRTIO_SND_PCM_RATE_44100 },
>> + { 48000, VIRTIO_SND_PCM_RATE_48000 },
>> + { 64000, VIRTIO_SND_PCM_RATE_64000 },
>> + { 88200, VIRTIO_SND_PCM_RATE_88200 },
>> + { 96000, VIRTIO_SND_PCM_RATE_96000 },
>> + { 176400, VIRTIO_SND_PCM_RATE_176400 },
>> + { 192000, VIRTIO_SND_PCM_RATE_192000 }
>> +};
>> +
>> +/**
>> + * virtsnd_pcm_release() - Release the PCM substream on the device side.
>> + * @substream: VirtIO substream.
>> + *
>> + * The function waits for all pending I/O messages to complete.
>> + *
>> + * Context: Any context that permits to sleep.
>> + * Return: 0 on success, -errno on failure.
>> + */
>> +static inline bool virtsnd_pcm_released(struct virtio_pcm_substream *substream)
>> +{
>> + return atomic_read(&substream->msg_count) == 0;
>
> All this use of atomic_read/atomic_set all over the place makes me pause.
> Could you add documentation explaining the use rules for these atomic fields?
I added some additional comments about that in v2:
[5/9] virtio_pcm_msg.c:virtsnd_pcm_msg_complete()
[6/9] virtio_pcm_ops.c:virtsnd_pcm_released()
>> +}
>> +
>> +static int virtsnd_pcm_release(struct virtio_pcm_substream *substream)
>> +{
>> + struct virtio_snd *snd = substream->snd;
>> + struct virtio_snd_msg *msg;
>> + unsigned int js = msecs_to_jiffies(msg_timeout_ms);
>> + int rc;
>> +
>> + msg = virtsnd_pcm_ctl_msg_alloc(substream, VIRTIO_SND_R_PCM_RELEASE,
>> + GFP_KERNEL);
>> + if (IS_ERR(msg))
>> + return PTR_ERR(msg);
>> +
>> + rc = virtsnd_ctl_msg_send_sync(snd, msg);
>> + if (rc)
>> + return rc;
>> +
>> + return wait_event_interruptible_timeout(substream->msg_empty,
>> + virtsnd_pcm_released(substream),
>> + js);
>> +}
>> +
>> +/**
>> + * virtsnd_pcm_open() - Open the PCM substream.
>> + * @substream: Kernel ALSA substream.
>> + *
>> + * Context: Any context.
>> + * Return: 0 on success, -errno on failure.
>> + */
>> +static int virtsnd_pcm_open(struct snd_pcm_substream *substream)
>> +{
>> + struct virtio_pcm *pcm = snd_pcm_substream_chip(substream);
>> + struct virtio_pcm_substream *ss = NULL;
>> +
>> + if (pcm) {
>> + switch (substream->stream) {
>> + case SNDRV_PCM_STREAM_PLAYBACK:
>> + case SNDRV_PCM_STREAM_CAPTURE: {
>> + struct virtio_pcm_stream *stream =
>> + &pcm->streams[substream->stream];
>> +
>> + if (substream->number < stream->nsubstreams)
>> + ss = stream->substreams[substream->number];
>> + break;
>> + }
>> + }
>> + }
>> +
>> + if (!ss)
>> + return -EBADFD;
>> +
>> + substream->runtime->hw = ss->hw;
>> + substream->private_data = ss;
>> +
>> + return 0;
>> +}
>> +
>> +/**
>> + * virtsnd_pcm_close() - Close the PCM substream.
>> + * @substream: Kernel ALSA substream.
>> + *
>> + * Context: Any context.
>> + * Return: 0.
>> + */
>> +static int virtsnd_pcm_close(struct snd_pcm_substream *substream)
>> +{
>> + return 0;
>> +}
>> +
>> +/**
>> + * virtsnd_pcm_hw_params() - Set the parameters of the PCM substream.
>> + * @substream: Kernel ALSA substream.
>> + * @hw_params: Hardware parameters (can be NULL).
>> + *
>> + * The function can be called both from the upper level (in this case,
>> + * @hw_params is not NULL) or from the driver itself (in this case, @hw_params
>> + * is NULL, and the parameter values are taken from the runtime structure).
>> + *
>> + * In all cases, the function:
>> + * 1. checks the state of the virtqueue and, if necessary, tries to fix it,
>> + * 2. sets the parameters on the device side,
>> + * 3. allocates a hardware buffer and I/O messages.
>> + *
>> + * Context: Any context that permits to sleep.
>> + * Return: 0 on success, -errno on failure.
>> + */
>> +static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
>> + struct snd_pcm_hw_params *hw_params)
>> +{
>> + struct snd_pcm_runtime *runtime = substream->runtime;
>> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
>> + struct virtio_device *vdev = ss->snd->vdev;
>> + struct virtio_snd_msg *msg;
>> + struct virtio_snd_pcm_set_params *request;
>> + snd_pcm_format_t format;
>> + unsigned int channels;
>> + unsigned int rate;
>> + unsigned int buffer_bytes;
>> + unsigned int period_bytes;
>> + unsigned int periods;
>> + unsigned int i;
>> + int vformat = -1;
>> + int vrate = -1;
>> + int rc;
>> +
>> + /*
>> + * If we got here after ops->trigger() was called, the queue may
>> + * still contain messages. In this case, we need to release the
>> + * substream first.
>> + */
>> + if (atomic_read(&ss->msg_count)) {
>> + rc = virtsnd_pcm_release(ss);
>> + if (rc) {
>> + dev_err(&vdev->dev,
>> + "SID %u: invalid I/O queue state\n",
>> + ss->sid);
>> + return rc;
>> + }
>> + }
>> +
>> + /* Set hardware parameters in device */
>> + if (hw_params) {
>> + format = params_format(hw_params);
>> + channels = params_channels(hw_params);
>> + rate = params_rate(hw_params);
>> + buffer_bytes = params_buffer_bytes(hw_params);
>> + period_bytes = params_period_bytes(hw_params);
>> + periods = params_periods(hw_params);
>> + } else {
>> + format = runtime->format;
>> + channels = runtime->channels;
>> + rate = runtime->rate;
>> + buffer_bytes = frames_to_bytes(runtime, runtime->buffer_size);
>> + period_bytes = frames_to_bytes(runtime, runtime->period_size);
>> + periods = runtime->periods;
>> + }
>> +
>> + for (i = 0; i < ARRAY_SIZE(g_a2v_format_map); ++i)
>> + if (g_a2v_format_map[i].alsa_bit == format) {
>> + vformat = g_a2v_format_map[i].vio_bit;
>> +
>> + break;
>> + }
>> +
>> + for (i = 0; i < ARRAY_SIZE(g_a2v_rate_map); ++i)
>> + if (g_a2v_rate_map[i].rate == rate) {
>> + vrate = g_a2v_rate_map[i].vio_bit;
>> +
>> + break;
>> + }
>> +
>> + if (vformat == -1 || vrate == -1)
>> + return -EINVAL;
>> +
>> + msg = virtsnd_pcm_ctl_msg_alloc(ss, VIRTIO_SND_R_PCM_SET_PARAMS,
>> + GFP_KERNEL);
>> + if (IS_ERR(msg))
>> + return PTR_ERR(msg);
>> +
>> + request = sg_virt(&msg->sg_request);
>> +
>> + request->buffer_bytes = cpu_to_virtio32(vdev, buffer_bytes);
>> + request->period_bytes = cpu_to_virtio32(vdev, period_bytes);
>> + request->channels = channels;
>> + request->format = vformat;
>> + request->rate = vrate;
>> +
>> + if (ss->features & (1U << VIRTIO_SND_PCM_F_MSG_POLLING))
>> + request->features |=
>> + cpu_to_virtio32(vdev,
>> + 1U << VIRTIO_SND_PCM_F_MSG_POLLING);
>> +
>> + if (ss->features & (1U << VIRTIO_SND_PCM_F_EVT_XRUNS))
>> + request->features |=
>> + cpu_to_virtio32(vdev,
>> + 1U << VIRTIO_SND_PCM_F_EVT_XRUNS);
>> +
>> + rc = virtsnd_ctl_msg_send_sync(ss->snd, msg);
>> + if (rc)
>> + return rc;
>> +
>> + /* If the buffer was already allocated earlier, do nothing. */
>> + if (runtime->dma_area)
>> + return 0;
>> +
>> + /* Allocate hardware buffer */
>> + rc = snd_pcm_lib_malloc_pages(substream, buffer_bytes);
>> + if (rc < 0)
>> + return rc;
>> +
>> + /* Allocate and initialize I/O messages */
>> + rc = virtsnd_pcm_msg_alloc(ss, periods, runtime->dma_area,
>> + period_bytes);
>> + if (rc)
>> + snd_pcm_lib_free_pages(substream);
>> +
>> + return rc;
>> +}
>> +
>> +/**
>> + * virtsnd_pcm_hw_free() - Reset the parameters of the PCM substream.
>> + * @substream: Kernel ALSA substream.
>> + *
>> + * The function does the following:
>> + * 1. tries to release the PCM substream on the device side,
>> + * 2. frees the hardware buffer.
>> + *
>> + * Context: Any context that permits to sleep.
>> + * Return: 0 on success, -errno on failure.
>> + */
>> +static int virtsnd_pcm_hw_free(struct snd_pcm_substream *substream)
>> +{
>> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
>> + int rc;
>> +
>> + rc = virtsnd_pcm_release(ss);
>> +
>> + /*
>> + * Even if we failed to send the RELEASE message or wait for the queue
>> + * flush to complete, we can safely delete the buffer. Because after
>> + * receiving the STOP command, the device must stop all I/O message
>> + * processing. If there are still pending messages in the queue, the
>> + * next ops->hw_params() call should deal with this.
>> + */
>> + snd_pcm_lib_free_pages(substream);
>> +
>> + return rc;
>> +}
>> +
>> +/**
>> + * virtsnd_pcm_hw_params() - Prepare the PCM substream.
>> + * @substream: Kernel ALSA substream.
>> + *
>> + * The function can be called both from the upper level or from the driver
>> + * itself.
>> + *
>> + * In all cases, the function:
>> + * 1. checks the state of the virtqueue and, if necessary, tries to fix it,
>> + * 2. prepares the substream on the device side.
>> + *
>> + * Context: Any context that permits to sleep. May take and release the tx/rx
>> + * queue spinlock.
>> + * Return: 0 on success, -errno on failure.
>> + */
>> +static int virtsnd_pcm_prepare(struct snd_pcm_substream *substream)
>> +{
>> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
>> + struct virtio_snd_queue *queue = virtsnd_pcm_queue(ss);
>> + struct virtio_snd_msg *msg;
>> + unsigned long flags;
>> + int rc;
>> +
>> + /*
>> + * If we got here after ops->trigger() was called, the queue may
>> + * still contain messages. In this case, we need to reset the
>> + * substream first.
>> + */
>> + if (atomic_read(&ss->msg_count)) {
>> + rc = virtsnd_pcm_hw_params(substream, NULL);
>> + if (rc)
>> + return rc;
>> + }
>> +
>> + spin_lock_irqsave(&queue->lock, flags);
>> + ss->msg_last_enqueued = -1;
>> + spin_unlock_irqrestore(&queue->lock, flags);
>> +
>> + /*
>> + * Since I/O messages are asynchronous, they can be completed
>> + * when the runtime structure no longer exists. Since each
>> + * completion implies incrementing the hw_ptr, we cache all the
>> + * current values needed to compute the new hw_ptr value.
>> + */
>> + ss->frame_bytes = substream->runtime->frame_bits >> 3;
>> + ss->period_size = substream->runtime->period_size;
>> + ss->buffer_size = substream->runtime->buffer_size;
>> +
>> + atomic_set(&ss->hw_ptr, 0);
>> + atomic_set(&ss->xfer_xrun, 0);
>> + atomic_set(&ss->msg_count, 0);
>> +
>> + msg = virtsnd_pcm_ctl_msg_alloc(ss, VIRTIO_SND_R_PCM_PREPARE,
>> + GFP_KERNEL);
>> + if (IS_ERR(msg))
>> + return PTR_ERR(msg);
>> +
>> + return virtsnd_ctl_msg_send_sync(ss->snd, msg);
>> +}
>> +
>> +/**
>> + * virtsnd_pcm_trigger() - Process command for the PCM substream.
>> + * @substream: Kernel ALSA substream.
>> + * @command: Substream command (SNDRV_PCM_TRIGGER_XXX).
>> + *
>> + * Depending on the command, the function does the following:
>> + * 1. enables/disables data transmission,
>> + * 2. starts/stops the substream on the device side.
>> + *
>> + * Context: Atomic context. May take and release the tx/rx queue spinlock.
>> + * Return: 0 on success, -errno on failure.
>> + */
>> +static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command)
>> +{
>> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
>> + struct virtio_snd *snd = ss->snd;
>> + struct virtio_snd_queue *queue = virtsnd_pcm_queue(ss);
>> + struct virtio_snd_msg *msg;
>> +
>> + switch (command) {
>> + case SNDRV_PCM_TRIGGER_START:
>> + case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: {
>> + int rc;
>> +
>> + spin_lock(&queue->lock);
>> + rc = virtsnd_pcm_msg_send(ss);
>> + spin_unlock(&queue->lock);
>> + if (rc)
>> + return rc;
>> +
>> + atomic_set(&ss->xfer_enabled, 1);
>> +
>> + msg = virtsnd_pcm_ctl_msg_alloc(ss, VIRTIO_SND_R_PCM_START,
>> + GFP_ATOMIC);
>> + if (IS_ERR(msg))
>> + return PTR_ERR(msg);
>> +
>> + return virtsnd_ctl_msg_send(snd, msg);
>> + }
>> + case SNDRV_PCM_TRIGGER_STOP:
>> + case SNDRV_PCM_TRIGGER_PAUSE_PUSH: {
>> + atomic_set(&ss->xfer_enabled, 0);
>> +
>> + msg = virtsnd_pcm_ctl_msg_alloc(ss, VIRTIO_SND_R_PCM_STOP,
>> + GFP_ATOMIC);
>> + if (IS_ERR(msg))
>> + return PTR_ERR(msg);
>> +
>> + return virtsnd_ctl_msg_send(snd, msg);
>> + }
>> + default: {
>> + return -EINVAL;
>> + }
>> + }
>> +}
>> +
>> +/**
>> + * virtsnd_pcm_pointer() - Get the current hardware position for the PCM
>> + * substream.
>> + * @substream: Kernel ALSA substream.
>> + *
>> + * Context: Atomic context.
>> + * Return: Hardware position in frames inside [0 ... buffer_size) range.
>> + */
>> +static snd_pcm_uframes_t
>> +virtsnd_pcm_pointer(struct snd_pcm_substream *substream)
>> +{
>> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
>> +
>> + if (atomic_read(&ss->xfer_xrun))
>> + return SNDRV_PCM_POS_XRUN;
>> +
>> + return (snd_pcm_uframes_t)atomic_read(&ss->hw_ptr);
>> +}
>> +
>> +/* PCM substream operators map. */
>> +const struct snd_pcm_ops virtsnd_pcm_ops = {
>> + .open = virtsnd_pcm_open,
>> + .close = virtsnd_pcm_close,
>> + .ioctl = snd_pcm_lib_ioctl,
>> + .hw_params = virtsnd_pcm_hw_params,
>> + .hw_free = virtsnd_pcm_hw_free,
>> + .prepare = virtsnd_pcm_prepare,
>> + .trigger = virtsnd_pcm_trigger,
>> + .pointer = virtsnd_pcm_pointer,
>> +};
>> --
>> 2.30.0
>>
>>
>
>
--
Anton Yakovlev
Senior Software Engineer
OpenSynergy GmbH
Rotherstr. 20, 10245 Berlin
Phone: +49 30 60 98 54 0
E-Mail: anton.yakovlev@...nsynergy.com
www.opensynergy.com
Handelsregister/Commercial Registry: Amtsgericht Charlottenburg, HRB 108616B
Geschäftsführer/Managing Director: Regis Adjamah
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