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Message-ID: <643248d4-d246-686f-34c3-7e592777e3ec@intel.com>
Date: Tue, 26 Jan 2021 10:22:49 +0100 (CET)
From: Guennadi Liakhovetski <guennadi.liakhovetski@...ux.intel.com>
To: Anton Yakovlev <anton.yakovlev@...nsynergy.com>
cc: virtualization@...ts.linux-foundation.org,
alsa-devel@...a-project.org, virtio-dev@...ts.oasis-open.org,
linux-kernel@...r.kernel.org, Jaroslav Kysela <perex@...ex.cz>,
Takashi Iwai <tiwai@...e.com>,
"Michael S. Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH v2 8/9] ALSA: virtio: introduce PCM channel map support
On Sun, 24 Jan 2021, Anton Yakovlev wrote:
> Enumerate all available PCM channel maps and create ALSA controls.
>
> Signed-off-by: Anton Yakovlev <anton.yakovlev@...nsynergy.com>
> ---
> sound/virtio/Makefile | 1 +
> sound/virtio/virtio_card.c | 15 +++
> sound/virtio/virtio_card.h | 8 ++
> sound/virtio/virtio_chmap.c | 237 ++++++++++++++++++++++++++++++++++++
> sound/virtio/virtio_pcm.h | 4 +
> 5 files changed, 265 insertions(+)
> create mode 100644 sound/virtio/virtio_chmap.c
[snip]
> diff --git a/sound/virtio/virtio_chmap.c b/sound/virtio/virtio_chmap.c
> new file mode 100644
> index 000000000000..8a2ddc4dcffb
> --- /dev/null
> +++ b/sound/virtio/virtio_chmap.c
> @@ -0,0 +1,237 @@
[snip]
> +/**
> + * virtsnd_chmap_parse_cfg() - Parse the channel map configuration.
> + * @snd: VirtIO sound device.
> + *
> + * This function is called during initial device initialization.
> + *
> + * Context: Any context that permits to sleep.
> + * Return: 0 on success, -errno on failure.
> + */
> +int virtsnd_chmap_parse_cfg(struct virtio_snd *snd)
> +{
> + struct virtio_device *vdev = snd->vdev;
> + unsigned int i;
> + int rc;
> +
> + virtio_cread(vdev, struct virtio_snd_config, chmaps, &snd->nchmaps);
> + if (!snd->nchmaps)
> + return 0;
> +
> + snd->chmaps = devm_kcalloc(&vdev->dev, snd->nchmaps,
> + sizeof(*snd->chmaps), GFP_KERNEL);
> + if (!snd->chmaps)
> + return -ENOMEM;
> +
> + rc = virtsnd_ctl_query_info(snd, VIRTIO_SND_R_CHMAP_INFO, 0,
> + snd->nchmaps, sizeof(*snd->chmaps),
> + snd->chmaps);
> + if (rc)
> + return rc;
> +
> + /* Count the number of channel maps per each PCM device/stream. */
> + for (i = 0; i < snd->nchmaps; ++i) {
> + struct virtio_snd_chmap_info *info = &snd->chmaps[i];
> + unsigned int nid = le32_to_cpu(info->hdr.hda_fn_nid);
> + struct virtio_pcm *pcm;
> + struct virtio_pcm_stream *stream;
> +
> + pcm = virtsnd_pcm_find_or_create(snd, nid);
> + if (IS_ERR(pcm))
> + return PTR_ERR(pcm);
> +
> + switch (info->direction) {
> + case VIRTIO_SND_D_OUTPUT: {
> + stream = &pcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
> + break;
> + }
> + case VIRTIO_SND_D_INPUT: {
> + stream = &pcm->streams[SNDRV_PCM_STREAM_CAPTURE];
> + break;
> + }
> + default: {
> + dev_err(&vdev->dev,
> + "chmap #%u: unknown direction (%u)\n", i,
> + info->direction);
> + return -EINVAL;
> + }
> + }
> +
> + stream->nchmaps++;
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * virtsnd_chmap_add_ctls() - Create an ALSA control for channel maps.
> + * @pcm: ALSA PCM device.
> + * @direction: PCM stream direction (SNDRV_PCM_STREAM_XXX).
> + * @stream: VirtIO PCM stream.
> + *
> + * Context: Any context.
> + * Return: 0 on success, -errno on failure.
> + */
> +static int virtsnd_chmap_add_ctls(struct snd_pcm *pcm, int direction,
> + struct virtio_pcm_stream *stream)
> +{
> + unsigned int i;
> + int max_channels = 0;
> +
> + for (i = 0; i < stream->nchmaps; i++)
> + if (max_channels < stream->chmaps[i].channels)
> + max_channels = stream->chmaps[i].channels;
> +
> + return snd_pcm_add_chmap_ctls(pcm, direction, stream->chmaps,
> + max_channels, 0, NULL);
> +}
> +
> +/**
> + * virtsnd_chmap_build_devs() - Build ALSA controls for channel maps.
> + * @snd: VirtIO sound device.
> + *
> + * Context: Any context.
> + * Return: 0 on success, -errno on failure.
> + */
> +int virtsnd_chmap_build_devs(struct virtio_snd *snd)
> +{
> + struct virtio_device *vdev = snd->vdev;
> + struct virtio_pcm *pcm;
> + struct virtio_pcm_stream *stream;
> + unsigned int i;
> + int rc;
> +
> + /* Allocate channel map elements per each PCM device/stream. */
> + list_for_each_entry(pcm, &snd->pcm_list, list) {
> + for (i = 0; i < ARRAY_SIZE(pcm->streams); ++i) {
> + stream = &pcm->streams[i];
> +
> + if (!stream->nchmaps)
> + continue;
> +
> + stream->chmaps = devm_kcalloc(&vdev->dev,
> + stream->nchmaps + 1,
> + sizeof(*stream->chmaps),
> + GFP_KERNEL);
> + if (!stream->chmaps)
> + return -ENOMEM;
> +
> + stream->nchmaps = 0;
> + }
> + }
> +
> + /* Initialize channel maps per each PCM device/stream. */
> + for (i = 0; i < snd->nchmaps; ++i) {
> + struct virtio_snd_chmap_info *info = &snd->chmaps[i];
> + unsigned int nid = le32_to_cpu(info->hdr.hda_fn_nid);
> + unsigned int channels = info->channels;
> + unsigned int ch;
> + struct snd_pcm_chmap_elem *chmap;
> +
> + pcm = virtsnd_pcm_find(snd, nid);
> + if (IS_ERR(pcm))
> + return PTR_ERR(pcm);
> +
> + if (info->direction == VIRTIO_SND_D_OUTPUT)
> + stream = &pcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
> + else
> + stream = &pcm->streams[SNDRV_PCM_STREAM_CAPTURE];
> +
> + chmap = &stream->chmaps[stream->nchmaps++];
> +
> + if (channels > ARRAY_SIZE(chmap->map))
> + channels = ARRAY_SIZE(chmap->map);
> +
> + chmap->channels = channels;
> +
> + for (ch = 0; ch < channels; ++ch) {
> + u8 position = info->positions[ch];
> +
> + if (position >= ARRAY_SIZE(g_v2a_position_map))
> + return -EINVAL;
> +
> + chmap->map[ch] = g_v2a_position_map[position];
> + }
> + }
You enter this function after virtsnd_chmap_parse_cfg() has run. And
virtsnd_chmap_parse_cfg() has already found or created all the PCMs and
counted channel maps - the same way as you do in the above loop. Wouldn't
it be enough to reuse the result of that counting and avoid re-counting
here?
> +
> + /* Create an ALSA control per each PCM device/stream. */
> + list_for_each_entry(pcm, &snd->pcm_list, list) {
> + if (!pcm->pcm)
> + continue;
> +
> + for (i = 0; i < ARRAY_SIZE(pcm->streams); ++i) {
> + stream = &pcm->streams[i];
> +
> + if (!stream->nchmaps)
> + continue;
> +
> + rc = virtsnd_chmap_add_ctls(pcm->pcm, i, stream);
> + if (rc)
> + return rc;
> + }
> + }
> +
> + return 0;
> +}
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