| Message ID | 1461763613-28714-2-git-send-email-hias@horus.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | beff053c0ef6983897e3481169292e6435ef0a2d |
| Headers | show |
> On 27.04.2016, at 15:26, Matthias Reichl <hias@horus.com> wrote: > > 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>
Matthias Reichl <hias@horus.com> writes: > 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. Acked-by: Eric Anholt <eric@anholt.net>
diff --git a/sound/soc/bcm/bcm2835-i2s.c b/sound/soc/bcm/bcm2835-i2s.c index 1c1f221..40ba01d 100644 --- a/sound/soc/bcm/bcm2835-i2s.c +++ b/sound/soc/bcm/bcm2835-i2s.c @@ -678,6 +678,15 @@ 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;
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> --- sound/soc/bcm/bcm2835-i2s.c | 9 +++++++++ 1 file changed, 9 insertions(+)