drm/i915: Protect DSPARB registers with a spinlock
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@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1480947208-18468-1-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8daa4fb..33758ac 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2191,6 +2191,9 @@ struct drm_i915_private {
} sagv_status;
struct {
+ /* protects DSPARB registers on pre-g4x/vlv/chv */
+ spinlock_t dsparb_lock;
+
/*
* Raw watermark latency values:
* in 0.1us units for WM0,