linux-kernel - Re: [PATCH 2/3] spi: sh-msiof: Convert to spi core auto_runtime

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Date:	Wed, 12 Mar 2014 10:23:48 +0900
From:	Magnus Damm <magnus.damm@...il.com>
To:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Mark Brown <broonie@...nel.org>,
	linux-spi <linux-spi@...r.kernel.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Geert Uytterhoeven <geert+renesas@...ux-m68k.org>
Subject: Re: [PATCH 2/3] spi: sh-msiof: Convert to spi core auto_runtime_pm framework

On Wed, Mar 12, 2014 at 1:32 AM, Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
> On Tuesday 11 March 2014 17:23:37 Geert Uytterhoeven wrote:
>> Hi Laurent,
>>
>> On Tue, Mar 11, 2014 at 4:55 PM, Laurent Pinchart wrote:
>> > Does this require drivers/sh/pm_runtime.c to be compiled in ?
>>
>> Let's check...
>>
>> My koelsch-legacy kernel has drivers/sh/pm_runtime.c compiled in.
>> My koelsch-reference kernel hasn't.
>>
>> However, under the -reference kernel many MSTP clocks (incl. MSIOF)
>> seem to be enabled all the time, while under -legacy they are enabled and
>> disabled on demand.
>
> Is PM_RUNTIME enabled in both cases ?
>
>
> There's something fishy in there that we should try to fix without too further
> much delay. Ben Dooks has pointed out the problem a couple of months ago, but
> the discussion on the mailing list just died.

Yes, Runtime PM is not working as expected in the multiplatform case,
that is true. I propose that we keep Runtime PM disabled in the
Kconfig for R-Car Gen2 for now to keep things simple.

>From my side I see it as two separate solutions. The short term fix is
to temporarily work around drivers that depend on Runtime PM for clock
control, I propose enabling selected clocks statically using the
function introduced by this series:

[PATCH 00/03] ARM: shmobile: Break out and extend clock workaround
http://www.spinics.net/lists/arm-kernel/msg310278.html

The long term fix I'm not sure sure about, but I trust Geert to figure
it out. =)

Regardless, rushing to fix this "correctly" seems as useful to me as
dead line driven DT development....

Thanks,

/ magnus
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