From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Currently we allow DRRS on IVB PCH ports, but we're missing a
few programming steps meaning it is guaranteed to not work.
And on HSW DRRS is not supported on anything but port A ever
as only transcoder EDP has the M2/N2 registers (though I'm
not sure if HSW ever has eDP on any other port).
Starting from BDW all transcoders have the dynamically
reprogrammable M/N registers so DRRS could work on any
port.
Stop initializing DRRS on ports where it cannot possibly work.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_drrs.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_drrs.c b/drivers/gpu/drm/i915/display/intel_drrs.c
index 53f014b4436b..9f673255578e 100644
--- a/drivers/gpu/drm/i915/display/intel_drrs.c
+++ b/drivers/gpu/drm/i915/display/intel_drrs.c
@@ -413,6 +413,7 @@ intel_drrs_init(struct intel_connector *connector,
struct drm_display_mode *fixed_mode)
{
struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
+ struct intel_encoder *encoder = connector->encoder;
struct drm_display_mode *downclock_mode = NULL;
INIT_DELAYED_WORK(&dev_priv->drrs.work, intel_drrs_downclock_work);
@@ -424,6 +425,13 @@ intel_drrs_init(struct intel_connector *connector,
return NULL;
}
+ if ((DISPLAY_VER(dev_priv) < 8 && !HAS_GMCH(dev_priv)) &&
+ encoder->port != PORT_A) {
+ drm_dbg_kms(&dev_priv->drm,
+ "DRRS only supported on eDP port A\n");
+ return NULL;
+ }
+
if (dev_priv->vbt.drrs_type != SEAMLESS_DRRS_SUPPORT) {
drm_dbg_kms(&dev_priv->drm, "VBT doesn't support DRRS\n");
return NULL;
--
2.34.1
