The dmaengine framework now exposes the granularity with which it is able to report the transfer residue for a certain DMA channel. Check the granularity in the generic dmaengine PCM driver and a) Set the SNDRV_PCM_INFO_BATCH if the granularity is per period or worse. b) Fallback to the (race condition prone) period counting if the driver does not support any residue reporting.
Signed-off-by: Lars-Peter Clausen lars@metafoo.de --- sound/soc/soc-generic-dmaengine-pcm.c | 37 +++++++++++++++++++++++++++++++++-- 1 file changed, 35 insertions(+), 2 deletions(-)
diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c index 87e8635..7bdee7b 100644 --- a/sound/soc/soc-generic-dmaengine-pcm.c +++ b/sound/soc/soc-generic-dmaengine-pcm.c @@ -144,6 +144,8 @@ static int dmaengine_pcm_set_runtime_hwparams(struct snd_pcm_substream *substrea if (ret == 0) { if (dma_caps.cmd_pause) hw.info |= SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME; + if (dma_caps.residue_granularity <= DMA_RESIDUE_GRANULARITY_SEGMENT) + hw.info |= SNDRV_PCM_INFO_BATCH; }
return snd_soc_set_runtime_hwparams(substream, &hw); @@ -282,6 +284,27 @@ static const struct snd_soc_platform_driver dmaengine_no_residue_pcm_platform = .probe_order = SND_SOC_COMP_ORDER_LATE, };
+static bool dmaengine_pcm_can_report_residue(struct dmaengine_pcm *pcm) +{ + struct dma_slave_caps dma_caps; + int ret; + int i; + + for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) { + if (!pcm->chan[i]) + continue; + + ret = dma_get_slave_caps(pcm->chan[i], &dma_caps); + if (ret != 0) + continue; + + if (dma_caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) + return false; + } + + return true; +} + static const char * const dmaengine_pcm_dma_channel_names[] = { [SNDRV_PCM_STREAM_PLAYBACK] = "tx", [SNDRV_PCM_STREAM_CAPTURE] = "rx", @@ -323,11 +346,21 @@ int snd_dmaengine_pcm_register(struct device *dev, if (!pcm) return -ENOMEM;
+ dmaengine_pcm_request_chan_of(pcm, dev); + + /* + * This will only return false if we know for sure that at least one + * channel does not support residue reporting. If the compat path is + * used for requesting the channels or the dma driver does not implement + * the slave_caps API we rely on the caller to set the NO_RESIDUE flag + * in case residue reporting is not supported. + */ + if (!dmaengine_pcm_can_report_residue(pcm)) + flags |= SND_DMAENGINE_PCM_FLAG_NO_RESIDUE; + pcm->config = config; pcm->flags = flags;
- dmaengine_pcm_request_chan_of(pcm, dev); - if (flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE) return snd_soc_add_platform(dev, &pcm->platform, &dmaengine_no_residue_pcm_platform);