[Intel-gfx] [PATCH 11/12] drm/i915/skl: New ddb allocation algorithm

[Maarten Lankhorst]

Op 15-05-17 om 10:34 schreef Mahesh Kumar:
> From: "Kumar, Mahesh" <mahesh1.kumar at intel.com>
>
> This patch implements new DDB allocation algorithm as per HW team
> recommendation. This algo takecare of scenario where we allocate less DDB
> for the planes with lower relative pixel rate, but they require more DDB
> to work.
> It also takes care of enabling same watermark level for each
> plane in crtc, for efficient power saving.
>
> Changes since v1:
>  - Rebase on top of Paulo's patch series
>
> Changes since v2:
>  - Fix the for loop condition to enable WM
>
> Changes since v3:
>  - Fix crash in cursor i-g-t reported by Maarten
>  - Rebase after addressing Paulo's comments
>  - Few other ULT fixes
> Changes since v4:
>  - Rebase on drm-tip
>  - Added separate function to enable WM levels
> Changes since v5:
>  - Fix a crash identified in skl-6770HQ system
My main fear is that we may now add crtc's that were not part of the state before, so anything that may change watermarks may cause a pageflip on a unrelated crtc to return -EBUSY.
However this only happens during atomic commit and might also happen on nonblocking modesets, so it's probably harmless for now.

Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>