linux-kernel - Re: [PATCH V3 1/4] regmap: Use regcache_mark_dirty() to indicate power loss or reset

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Message-ID: <5547AD4D.4000007@metafoo.de>
Date:	Mon, 04 May 2015 19:33:01 +0200
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Kevin Cernekee <cernekee@...omium.org>
CC:	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>, dgreid@...omium.org,
	Andrew Bresticker <abrestic@...omium.org>,
	Olof Johansson <olofj@...omium.org>,
	alsa-devel@...a-project.org, devicetree@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3 1/4] regmap: Use regcache_mark_dirty() to indicate
 power loss or reset

On 05/04/2015 04:05 PM, Kevin Cernekee wrote:
> On Sun, May 3, 2015 at 11:38 PM, Lars-Peter Clausen <lars@...afoo.de> wrote:
>>> diff --git a/drivers/base/regmap/regcache.c
>>> b/drivers/base/regmap/regcache.c
>>> index 7eb7b3b98794..63af3103d0c6 100644
>>> --- a/drivers/base/regmap/regcache.c
>>> +++ b/drivers/base/regmap/regcache.c
>>> @@ -253,6 +253,9 @@ static int regcache_default_sync(struct regmap *map,
>>> unsigned int min,
>>>                                   unsigned int max)
>>>    {
>>>          unsigned int reg;
>>> +       bool no_sync_defaults = map->no_sync_defaults;
>>> +
>>> +       map->no_sync_defaults = false;
>>
>>
>> This needs to be done at the end in regcache_sync(), the same place where
>> dirty is set to false.
>
> But map->cache_dirty means "any register is dirty," not "all registers
> are dirty."  So it can only be cleared after a successful flush.
>
> If one of the writes fails and regcache_sync() has to return
> prematurely, we probably don't want no_sync_defaults to stay true
> because some of the HW registers might not match map->reg_defaults
> anymore.

Makes sense. But it should still be done in a central place rather than 
repeating it in every sync implementation. You can still put it at the end 
of regcache_sync(), just clear it regardless of whether it succeeded or not.

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