Re: [RFC v2 4/7] ASoC: dmaengine_pcm: add copy support

On Wed, Feb 15, 2017 at 04:46:44PM +0100, Arnaud Pouliquen wrote:

On 02/15/2017 03:53 PM, Mark Brown wrote:

quoted

On Wed, Feb 15, 2017 at 02:59:18PM +0100, Arnaud Pouliquen wrote:

quoted

No, copy() is an alternative to doing DMA rather than something
that works with DMA.  If you want to have some sort of post
processing operation it shoudn't be called copy().  It's probably
worth considering just making a new format and letting userspace
convert things here.

You mean using a plug-in alsa to do it? this seems not possible with
tiny-alsa...
Without a plug-in, driver will not be compatible with standard audio
application.

Right.  But if you're using tinyalsa you've got some open coded system
specific stuff anyway!

Do you think this would be reasonable if i implement something similar
in my driver, without using the soc generic DMA engine?

Probably.  It might even be possible to fit it elegently into the
generic dmaengine code, just don't say it's a copy() operation since
that's a specific thing in ALSA.
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Hello Mark,

Sorry for the late answer, i was OoO...

On 02/16/2017 09:14 PM, Mark Brown wrote:

On Wed, Feb 15, 2017 at 04:46:44PM +0100, Arnaud Pouliquen wrote:

quoted

On 02/15/2017 03:53 PM, Mark Brown wrote:

quoted

On Wed, Feb 15, 2017 at 02:59:18PM +0100, Arnaud Pouliquen
wrote:

quoted

quoted

No, copy() is an alternative to doing DMA rather than
something that works with DMA.  If you want to have some sort
of post processing operation it shoudn't be called copy().
It's probably worth considering just making a new format and
letting userspace convert things here.

quoted

You mean using a plug-in alsa to do it? this seems not possible
with tiny-alsa... Without a plug-in, driver will not be
compatible with standard audio application.

Right.  But if you're using tinyalsa you've got some open coded
system specific stuff anyway!

quoted

Do you think this would be reasonable if i implement something
similar in my driver, without using the soc generic DMA engine?

Probably.  It might even be possible to fit it elegently into the 
generic dmaengine code, just don't say it's a copy() operation
since that's a specific thing in ALSA.

Ok I will have a look in generic dmaengine and try to propose
something in this way in the V2.

Regards,
Arnaud