[Intel-gfx] [PATCH] drm/i915: Handle changing enable_fbc parameter at runtime better.

[Maarten Lankhorst]

Op 06-03-18 om 21:02 schreef Rodrigo Vivi:
> On Tue, Mar 06, 2018 at 11:22:16AM +0100, Maarten Lankhorst wrote:
>> Op 05-03-18 om 19:50 schreef Rodrigo Vivi:
>>> On Mon, Mar 05, 2018 at 01:36:08PM +0100, Maarten Lankhorst wrote:
>>>> If i915.enable_fbc is cleared at runtime, but FBC was previously enabled
>>>> then we don't disable FBC until the next time the crtc is disabled.
>>>>
>>>> Make sure that if the module param is changed, we disable FBC in
>>>> intel_fbc_post_update so we never have to worry about disabling.
>>> What about switching this from a parameter to debugfs toggle like drrs?
>> There are still places where people recommend booting with i915.enable_fbc=0, this would break if we moved it to debugfs.
> I think this was exactly what Chris and Joonas were trying to avoid when removing enable_rc6.
> To avoid random recommendations of unvalidated combinations.
>
>> Having a small fix is enough.
>>
> Well... it would be fine for me.
>
> But I went to look the patch and I don't know what exactly we are trying to fix here.
>
> I don't know if it is safe to disable it like this when crtc is already enabled
> and mostly: why?! why just not wait until next modeset?
>
> Cc: Paulo
I'm trying to get rid of all modesets in kms_frontbuffer_tracking, they add up on glk where it's 50% of the total runtime for kms tests. :)

~Maarten