On 03/13/2014 02:03 PM, Peter Ujfalusi wrote:
On 03/13/2014 12:28 PM, Lars-Peter Clausen wrote:
+int edma_pcm_platform_register(struct device *dev)
+{
+ if (dev->of_node)
+ return snd_dmaengine_pcm_register(dev,
+ &edma_dmaengine_pcm_config,
+ SND_DMAENGINE_PCM_FLAG_NO_RESIDUE);
Since the edma dmaengine driver implements the slave cap API there is no need
to manually specify SND_DMAENGINE_PCM_FLAG_NO_RESIDUE manually. But since the
edma driver sets the granularity to DMA_RESIDUE_GRANULARITY_DESCRIPTOR in this
case the generic dmaengine will not set SND_DMAENGINE_PCM_FLAG_NO_RESIDUE
automatically since it assumes that the dmaengine driver is capable of
properly reporting the DMA position.
Hrm, I see. For eDMA I think we can support DMA_RESIDUE_GRANULARITY_SEGMENT
granularity. Since according to the documentation the _SEGMENT means that the
DMA position will be updated per periods, which is basically the same thing
what we are doing at the moment when the granularity is
DMA_RESIDUE_GRANULARITY_DESCRIPTOR.
From ALSA point of view at least they are the same: neither of them can report
exact position, the DMA pointer jumps from period to period.
IMHO in the generic dmaengine PCM we should set the SNDRV_PCM_INFO_BATCH for
both cases.
Ups, sorry mixed up DMA_RESIDUE_GRANULARITY_SEGMENT and
DMA_RESIDUE_GRANULARITY_DESCRIPTOR. You can just remove the
SND_DMAENGINE_PCM_FLAG_NO_RESIDUE when registering the dmaengine PCM driver
and everything will still work as expected.
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