@@ -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);
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(-)