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

[Kevin Cernekee]

On Sun, May 3, 2015 at 11:38 PM, Lars-Peter Clausen <lars at metafoo.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.

Leaving it set to true wouldn't break the current regcache_sync()
implementation, but no_sync_defaults is documented as: "if set, the HW
registers are known to match map->reg_defaults".  Writing any register
to a non-default value makes it false.