[Intel-xe] [PATCH v6 1/2] drm/xe/display: Don't try to use vram if not available

[Juha-Pekka Heikkila]

On 17.10.2023 14.38, Ruhl, Michael J wrote:
>> -----Original Message-----
>> From: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
>> Sent: Tuesday, October 17, 2023 7:13 AM
>> To: Ruhl, Michael J <michael.j.ruhl at intel.com>; intel-xe at lists.freedesktop.org
>> Subject: Re: [PATCH v6 1/2] drm/xe/display: Don't try to use vram if not
>> available
>>
>> On 16.10.2023 18.03, Ruhl, Michael J wrote:
>>>> -----Original Message-----
>>>> From: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
>>>> Sent: Monday, October 16, 2023 10:54 AM
>>>> To: Ruhl, Michael J <michael.j.ruhl at intel.com>
>>>> Subject: Fwd: [PATCH v6 1/2] drm/xe/display: Don't try to use vram if not
>>>> available
>>>>
>>>> Trying to get bo from vram when vram not available will cause
>>>> WARN_ON() hence avoid touching vram if not available.
>>>>
>>>> Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
>>>> ---
>>>>    drivers/gpu/drm/xe/display/xe_fb_pin.c | 11 ++++++-----
>>>>    1 file changed, 6 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/xe/display/xe_fb_pin.c
>>>> b/drivers/gpu/drm/xe/display/xe_fb_pin.c
>>>> index 2c36e5032433..89cf65c58191 100644
>>>> --- a/drivers/gpu/drm/xe/display/xe_fb_pin.c
>>>> +++ b/drivers/gpu/drm/xe/display/xe_fb_pin.c
>>>> @@ -62,11 +62,12 @@ static int __xe_pin_fb_vma_dpt(struct
>>>> intel_framebuffer *fb,
>>>>    		dpt_size = ALIGN(intel_rotation_info_size(&view->rotated) * 8,
>>>>    				 XE_PAGE_SIZE);
>>>>    -	dpt = xe_bo_create_pin_map(xe, tile0, NULL, dpt_size,
>>>> -				  ttm_bo_type_kernel,
>>>> -				  XE_BO_CREATE_VRAM0_BIT |
>>>> -				  XE_BO_CREATE_GGTT_BIT);
>>>> -	if (IS_ERR(dpt))
>>>> +	if (IS_DGFX(xe))
>>>> +		dpt = xe_bo_create_pin_map(xe, tile0, NULL, dpt_size,
>>>> +					   ttm_bo_type_kernel,
>>>> +					   XE_BO_CREATE_VRAM0_BIT |
>>>> +					   XE_BO_CREATE_GGTT_BIT);
>>>> +	else
>>>>    		dpt = xe_bo_create_pin_map(xe, tile0, NULL, dpt_size,
>>>>    					   ttm_bo_type_kernel,
>>>>    					   XE_BO_CREATE_STOLEN_BIT |
>>>
>>> Hi Juha,
>>>
>>> You have changed this code from:
>>>
>>> "Best effort allocation" (try vram, and then fallback to stolen), to "Discrete
>> gets vram, !discrete gets
>>> stolen".
>>
>> Hi Michael,
>>
>> this is correct. vram is for discrete and stolen is found on integrated.
>> Earlier pattern was copied from i915 way of setting up display page
>> table but it had to be changed because asking for vram on Xe while on
>> discrete will cause WARN_ON() hence exact same pattern from i915
>> couldn't be used.
> 
> Ok, that makes sense.  If there is still time, I would suggest updating the commit
> message to say something like:
> 
> --
> Discrete should us vram only.  Current allocation allows a fallback.
> Update display allocation to require vram for discrete.
> --
> 
> Or something like that so the commit message tells us why the change is happening.
> 

Alas this was merged already to drm-xe-next.

/Juha-Pekka

>>
>>>
>>> If this is correct:
>>>
>>> Reviewed-by: Michael J. Ruhl <michael.j.ruhl at intel.com>
>>>
>>> Is this new sematic the "correct" allocation method?
>>>
>>> Thanks,
>>>
>>> Mike
>>>
>>>
>>>> --
>>>> 2.25.1
>>>
>