[PATCH v3] drm/i915: Flush WC GGTT only on required platforms

[Nirmoy Das]

Hi Andi,

On 10/18/2023 1:49 PM, Andi Shyti wrote:
> Hi Nirmoy,
>
> On Wed, Oct 18, 2023 at 11:38:15AM +0200, Nirmoy Das wrote:
>> gen8_ggtt_invalidate() is only needed for limited set of platforms
>> where GGTT is mapped as WC. This was added as way to fix WC based GGTT in
>> commit 0f9b91c754b7 ("drm/i915: flush system agent TLBs on SNB") and
>> there are no reference in HW docs that forces us to use this on non-WC
>> backed GGTT.
>>
>> This can also cause unwanted side-effects on XE_HP platforms where
>> GFX_FLSH_CNTL_GEN6 is not valid anymore.
>>
>> v2: Add a func to detect wc ggtt detection (Ville)
>> v3: Improve commit log and add reference commit (Daniel)
>>
>> Fixes: d2eae8e98d59 ("drm/i915/dg2: Drop force_probe requirement")
> I'm wondering if this is the right Fixes, though. Should this
> rather be:
>
> Fixes: 6266992cf105 ("drm/i915/gt: remove GRAPHICS_VER == 10")

Hard to find a real Fixes for this. I just want to backport this to dg2 
where we can have unwanted side-effects.


Regards,

Nirmoy

>
> ?
>
> Andi