[Intel-gfx] [PATCH v6 02/12] drm/i915/mtl: Synchronize i915/BIOS on C6 enabling

[Belgaumkar, Vinay]

On 3/16/2023 8:43 PM, Dixit, Ashutosh wrote:
> On Wed, 15 Mar 2023 18:00:51 -0700, Umesh Nerlige Ramappa wrote:
>> From: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
> Hi Vinay,
>
>> If BIOS enables/disables C6, i915 should do the same.
> So MTL bios has a control for enabling/disabling C6? Both RC6 and MC6
> individually or collectively?
Yes, we can toggle both independently in BIOS.
>
> What happens if bios has disabled RC6 and i915 enables it: just that it
> will bust OA?

Yes, since OA init will rely on this information.

Thanks,

Vinay.

>
> The patch itself LGTM if the above is true, I can R-b it after I hear about
> the above.
>
> Thanks.
> --
> Ashutosh
>
>> Also, retain this value across driver reloads. This is needed only for
>> MTL as of now due to an existing bug in OA which needs C6 disabled for it
>> to function. BIOS behavior is also different across platforms in terms of
>> how C6 is enabled.
>>
>> Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar at intel.com>