drm/radeon/kms: display watermark updates (v2)

- Add module option to force the display priority
  0 = auto, 1 = normal, 2 = high
- Default to high on r3xx/r4xx/rv515 chips
  Fixes flickering problems during heavy acceleration
  due to underflow to the display controllers
- Fill in minimal support for RS600

v2 - update display priority when bandwidth is updated
so the user can change the parameter at runtime and it
will take affect on the next modeset.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index 739a447..138ddd4 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -2389,6 +2389,8 @@
 	uint32_t pixel_bytes1 = 0;
 	uint32_t pixel_bytes2 = 0;
 
+	radeon_update_display_priority(rdev);
+
 	if (rdev->mode_info.crtcs[0]->base.enabled) {
 		mode1 = &rdev->mode_info.crtcs[0]->base.mode;
 		pixel_bytes1 = rdev->mode_info.crtcs[0]->base.fb->bits_per_pixel / 8;