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>

drivers/gpu/drm/radeon/radeon_drv.c

@@ -92,6 +92,7 @@ int radeon_tv = 1;
 int radeon_new_pll = -1;
 int radeon_dynpm = -1;
 int radeon_audio = 1;
+int radeon_disp_priority = 0;
 
 MODULE_PARM_DESC(no_wb, "Disable AGP writeback for scratch registers");
 module_param_named(no_wb, radeon_no_wb, int, 0444);
@@ -135,6 +136,9 @@ module_param_named(dynpm, radeon_dynpm, int, 0444);
 MODULE_PARM_DESC(audio, "Audio enable (0 = disable)");
 module_param_named(audio, radeon_audio, int, 0444);
 
+MODULE_PARM_DESC(disp_priority, "Display Priority (0 = auto, 1 = normal, 2 = high)");
+module_param_named(disp_priority, radeon_disp_priority, int, 0444);
+
 static int radeon_suspend(struct drm_device *dev, pm_message_t state)
 {
 	drm_radeon_private_t *dev_priv = dev->dev_private;