drm/i915: Optimize VLV/CHV display FIFO updates

Use I915_{READ,WRITE}_FW() for updating the DSPARB registers on
VLV/CHV. This is less expesive as we can grab the uncore.lock across
the entire sequence of reads and writes instead of each register
access grabbing it.

This also allows us to eliminate the dsparb lock entirely as the
uncore.lock now effectively protects the contents of the DSPARB
registers.

v2: Add a note that interrupts are already disabled (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170309154434.29303-6-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 1af5471..e312b61 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -825,7 +825,6 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
 
 	spin_lock_init(&dev_priv->mm.object_stat_lock);
 	spin_lock_init(&dev_priv->mmio_flip_lock);
-	spin_lock_init(&dev_priv->wm.dsparb_lock);
 	mutex_init(&dev_priv->sb_lock);
 	mutex_init(&dev_priv->modeset_restore_lock);
 	mutex_init(&dev_priv->av_mutex);