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

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Date:	Fri, 22 Apr 2016 15:08:43 +0300
From:	Tero Kristo <t-kristo@...com>
To:	Peter Ujfalusi <peter.ujfalusi@...com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Mark Brown <broonie@...nel.org>
CC:	<alsa-devel@...a-project.org>,
	Michael Turquette <mturquette@...libre.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Jyri Sarha <jsarha@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	<linux-clk@...r.kernel.org>
Subject: Re: [alsa-devel] [PATCH 4/4] ASoC: simple-card: Support for selecting
 system clocks by ID

On 22/04/16 14:52, Peter Ujfalusi wrote:
> On 04/22/16 01:29, Stephen Boyd wrote:
>>>> 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...
>>>
>>> Well, at least long term we do need daVinci converting to CCF - this is
>>> going to continue to cause problems, devices not part of the SoC can and
>>> do contain clocks and are going to end up being supported via the clock
>>> API.
>>
>> Does anyone here know what's involved in converting daVinci to
>> CCF? It doesn't look too far off from what is in the CCF today,
>> so I'm not sure what's blocking the transition.
>
> Not entirely sure, but most likely new clk driver(s) for daVinci under
> drivers/clk/ti/ new set of structures to describe the clocks if the ti_clk* is
> not applicable I guess for starter. Support for DT, non DT boots as most of
> daVinci is not booting with DT and most likely never will.
> It might help to have different daVinci boards for testing the transition. I
> only have OMAP-L138-evm. I don't think it is enough for testing an entire
> architecture for this big change...
>
> Tero might have better estimates on what is involved when switching an
> architecture to CCF from custom, but at least synchronized API - so we don't
> need to convert drivers at least.
>

Davinci is currently a mutant architecture, it is overriding the common 
clk APIs and using its own. Converting these to CCF may open a can of 
worms in many ways.

All the clock data should be converted to support CCF, (from 
arch/arm/mach-davinci/), along with whatever Peter said.

This also in a situation where many/most upstream people don't even have 
davinci devices... Personally I have a grand total of zero davinci 
boards on my desk so at least I am unable to work on this right now.

-Tero