[Intel-gfx] [PATCH v4 4/5] i2c: designware-baytrail: Disallow the CPU to enter C6 or C7 while holding the punit semaphore

[Jarkko Nikula]

On 12/13/2016 11:56 AM, Andy Shevchenko wrote:
> On Mon, 2016-12-12 at 22:56 +0100, Hans de Goede wrote:
>> On my cherrytrail tablet with axp288 pmic, just doing a bunch of
>> repeated
>> reads from the pmic, e.g. "i2cdump -y 14 0x34" would lookup the tablet
>> in
>> 1 - 3 runs guaranteed.
>>
>> This seems to be causes by the cpu trying to enter C6 or C7 while we
>> hold
>> the punit bus semaphore, at which point everything just hangs.
>>
>> Avoid this by disallowing the CPU to enter C6 or C7 before acquiring
>> the
>> punit bus semaphore.
>>
>
> Just a nitpick for abbreviations: pmic -> PMIC, punit -> P-Unit, but I'm
> okay with the contents which is more important.
>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
>
No need for v5 from my side either (Andy agreed it later in the thread)

Acked-by: Jarkko Nikula <jarkko.nikula at linux.intel.com>

>> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=109051
>
> What would be good is to have comments / tags from Len and Ville.
>
We can have also follow up patch if some other PM QoS acrobatics are 
required than what's implemented here. Getting real bug fixed is quite 
big benefit.