On 03/13/2014 10:18 AM, Peter Ujfalusi wrote:
[...]
+static const struct snd_pcm_hardware edma_pcm_hardware = {
+ .info = SNDRV_PCM_INFO_MMAP |
+ SNDRV_PCM_INFO_MMAP_VALID |
+ SNDRV_PCM_INFO_BATCH |
+ SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME |
+ SNDRV_PCM_INFO_INTERLEAVED,
+ .buffer_bytes_max = 128 * 1024,
+ .period_bytes_min = 32,
+ .period_bytes_max = 64 * 1024,
+ .periods_min = 2,
+ .periods_max = 19, /* Limit by edma dmaengine driver */
+};
The idea is that we can auto-discover all the things using the
dma_slave_caps API. Too bad we removed the possibility to specify the
maximum number of segments from the API. Maybe we need to add it back. Is
the 19 a hard-limit or could it be worked around by software in the
dmaengine driver?
+
+static const struct snd_dmaengine_pcm_config edma_dmaengine_pcm_config = {
+ .pcm_hardware = &edma_pcm_hardware,
+ .prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config,
+ .prealloc_buffer_size = 128 * 1024,
Unless there is a very good reason for exactly this size, just leave it 0
and let the generic dmaengine driver use the default.
+};
+
+static const struct snd_dmaengine_pcm_config edma_compat_dmaengine_pcm_config
= {
+ .pcm_hardware = &edma_pcm_hardware,
+ .prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config,
+ .compat_filter_fn = edma_filter_fn,
+ .prealloc_buffer_size = 128 * 1024,
+};
There is no need for different configs for DT and non-DT.
+
+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.
+ else
+ return snd_dmaengine_pcm_register(dev,
+ &edma_compat_dmaengine_pcm_config,
+ SND_DMAENGINE_PCM_FLAG_NO_RESIDUE |
+ SND_DMAENGINE_PCM_FLAG_NO_DT |
+ SND_DMAENGINE_PCM_FLAG_COMPAT);
If you set the flags to just SND_DMAENGINE_PCM_FLAG_COMPAT it will do the
right thing in the generic dmaengine driver depending on whether
dev->of_node is set or not.
There is also a devm_ version of snd_dmaengine_pcm_register() it probably
makes sense to use it here.
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