[PATCH 3/5] ASoC: soc-generic-dmaengine-pcm: Add custom prepare and submit function

[Pierre-Louis Bossart]

On 11/16/20 1:58 PM, Mark Brown wrote:
> On Mon, Nov 16, 2020 at 02:19:03PM +0800, Michael Sit Wei Hong wrote:
> 
>> In the Intel KeemBay solution, the DW AXI-based DMA has a limitation on
>> the number of DMA blocks per transfer. In the case of 16 bit audio ASoC
>> would allocate blocks exceeding the DMA block limitation.
> 
>> The ASoC layers are not aware of such DMA limitation, and the DMA engine
>> does not provide an API to set the maximum number of blocks per linked link.
> 
> Can we not extend the dmaengine API so that the ASoC layer (and any
> other users) can become aware of this limitation and handle it
> appropriately rather than jumping straight to some client driver
> specific handling?

This was supposed to be an RFC, I asked Vinod/Lars to be copied for 
feedback. Unfortunately the RFC tag is missing and Vinod's email wasn't 
the right one... (fixed now).

This patchset suggests an ALSA-only quirk, having other more generic 
means to deal with this limitation would be fine - we just wanted to 
have a discussion on preferred directions. The IPs used are not 
Intel-specific so sooner or later someone else will have similar 
limitations to work-around.