Re: [alsa-devel] [PATCH 4/4] ASoC: simple-card: Support for selecting system clocks by ID

From: Peter Ujfalusi
Date: Mon Apr 18 2016 - 11:52:29 EST

On 02/17/2016 09:52 PM, Peter Ujfalusi wrote:
> On 02/17/2016 02:07 PM, Mark Brown wrote:
>> On Wed, Feb 17, 2016 at 10:13:35AM +0200, Peter Ujfalusi wrote:
>>> With this change we don't need to write custom machine drivers for setup not
>>> using sysclk_id == 0.
>>> I do think this is reasonable change by itself.
>>> However I do think that the current simple-card is flawed regarding to clock
>>> selection and the change Jyri and me are proposing is reasonable.
>> But you define a new ABI to specify it in the process, I'd rather fix
>> the flaws by using the common clock ABI than extend any device stuff.
>> If it didn't define a new ABI I'd probably not worry about it but one of
>> the issues we have with DT is that we do end up making ABIs every time
>> we put something in DT.
> I understand. This should have been supported by simple-card since the
> beginning. When we tried to move all boards to use simple-card, we hit the
> wall by not being able to select and configure other sysclk_id than 0.
> I don't want to create yet another simple card which handles only sysclk_id 1 ;)
> On the other hand this ABI is backwards compatible since if it is missing it
> will default to the configuration we right now have regarding to sysclk_dir
> and sysclk_id.
> I will look at the CCF implementation for McASP first then for aic3x.

The first issue with converting the McASP to use CCF internally for clock
selection, muxing and rate configuration is that the daVinci platform does not
use CCF at all. Given that the davinci-mcasp driver is used by daVinci, we
need to have non CCF way supported in ASoC...