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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@opensynergy.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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