[Intel-gfx] [PATCH v2 11/15] drm/i915: Protect DSPARB registers with a spinlock

[Maarten Lankhorst]

Op 05-12-16 om 15:13 schreef ville.syrjala at linux.intel.com:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Each DSPARB register can house bits for two separate pipes, hence
> we must protect the registers during reprogramming so that parallel
> FIFO reconfigurations happening simultaneosly on multiple pipes won't
> corrupt each others values.
>
> We'll use a new spinlock for this instead of the wm_mutex since we'll
> have to move the DSPARB programming to happen from the vblank evade
> critical section, and we can't use mutexes in there.
>
> v2: Document why we use a spinlock instead of a mutex (Maarten)
>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>