Re: [PATCH 5/7] ALSA: virtio: PCM substream operators

On 20.01.2021 09:36, Michael S. Tsirkin wrote:

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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@opensynergy.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