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| author |   Matthias Reichl <hias@horus.com> | 2016-04-27 15:26:52 +0200 |
|---|---|---|
| committer |   Mark Brown <broonie@kernel.org> | 2016-04-27 17:35:53 +0100 |
| commit | beff053c0ef6983897e3481169292e6435ef0a2d (patch) | |
| tree | 16563f94c189398a71631aca60322e52a1fe1f20 /sound | |
| parent | Merge branch 'topic/dmaengine' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into asoc-bcm2835 (diff) | |
| download | linux-dev-beff053c0ef6983897e3481169292e6435ef0a2d.tar.xz linux-dev-beff053c0ef6983897e3481169292e6435ef0a2d.zip | |
ASoC: bcm2835: Add S16_LE support via packed DMA transfers
The bcm2835-i2s driver already has support for the S16_LE format but
that format hasn't been made available because dmaengine_pcm didn't
support packed data transfers.
bcm2835-i2s needs 16-bit left+right channel data to be packed into
a 32-bit word, the FIFO register is 32-bit only and doesn't support
16-bit access.
Now that dmaengine_pcm supports packed transfers the format can
be made available by setting the SND_DMAENGINE_PCM_DAI_FLAG_PACK flag.
No further configuration is necessary:
- snd_dmaengine_dai_dma_data.addr_width is already set to
DMA_SLAVE_BUSWIDTH_4_BYTES to force 32-bit DMA transfers
- dmaengine_pcm will pick up the S16_LE format from the DAI
configuration and make it available since it's no longer
masked out due to the PACK flag.
- there are no further corner cases to catch in hw_params,
since the channel count is fixed at 2 we always have two
16-bit stereo samples that can be transferred via 32-bit DMA
Signed-off-by: Matthias Reichl <hias@horus.com>
Tested-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/soc/bcm/bcm2835-i2s.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/sound/soc/bcm/bcm2835-i2s.c b/sound/soc/bcm/bcm2835-i2s.c index a0026e2d2f0a..6ba20498202e 100644 --- a/sound/soc/bcm/bcm2835-i2s.c +++ b/sound/soc/bcm/bcm2835-i2s.c @@ -690,6 +690,15 @@ static int bcm2835_i2s_probe(struct platform_device *pdev) dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK].maxburst = 2; dev->dma_data[SNDRV_PCM_STREAM_CAPTURE].maxburst = 2; + /* + * Set the PACK flag to enable S16_LE support (2 S16_LE values + * packed into 32-bit transfers). + */ + dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK].flags = + SND_DMAENGINE_PCM_DAI_FLAG_PACK; + dev->dma_data[SNDRV_PCM_STREAM_CAPTURE].flags = + SND_DMAENGINE_PCM_DAI_FLAG_PACK; + /* BCLK ratio - use default */ dev->bclk_ratio = 0; |