Hi,
Changes since v1: - the hw.formats mask preparation moved to dmaengine_pcm_set_runtime_hwparams() - we prepare the mask for all supported sample formats based on the physical width of the sample and beased on the slave_caps information.
I have noticed while switching the daVinci audio to dmaengine_pcm that the _3LE and _3BE support is not working correctly via dmaengine_pcm: In case of _3LE/_3BE formats the samples are stored in 3 consecutive bytes without padding it to 4 bytes. This means that the DMA needs to be able to support 3 bytes word length in order to read/write the samples from memory correctly. Originally the code treated 24 bits physical length samples as they were 32 bits which leads to corruption when playing or recording audio.
To fix the support for 3 bytes physical samples the dma driver also need to have support for such data arrangement. eDMA does have support for it in HW and the legacy davinci-pcm platform driver w/o dmaengine was able to support such formats.
First step is to add DMA_SLAVE_BUSWIDTH_3_BYTES to dma_slave_buswidth for engines and users to select 3 bytes as bus width.
Followed by: In dmaengine_pcm_set_runtime_hwparams() we should check the slave_caps of the dma if it supports the give sample physical width of the sample. Based on this information we initialize the hw.formats: masking out all non supported formats based on the physical width. In case the dma driver does not implement the slave_caps the default assumption is that it supports 1, 2 and 4 bytes widths.
Regards, Peter --- Peter Ujfalusi (5): dma: Support for 3 bytes word size ALSA: pcm_dmaengine: Use the available wrapper to get physical width ASoC: generic-dmaengine-pcm: Prepare formats mask for valid physical sample sizes ALSA: pcm_dmaengine: Correct support for 24bits physical sample widths dma: edma: Declare DMA_SLAVE_BUSWIDTH_3_BYTES as supported buswidth
drivers/dma/edma.c | 1 + include/linux/dmaengine.h | 1 + sound/core/pcm_dmaengine.c | 4 +++- sound/soc/soc-generic-dmaengine-pcm.c | 26 +++++++++++++++++++++++++- 4 files changed, 30 insertions(+), 2 deletions(-)