From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> commit ee59792c97176f12c1da31f29fc4c2aab187f06e upstream. 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> Link: https://patchwork.freedesktop.org/patch/msgid/20220128103757.22461-11-ville.syrjala@xxxxxxxxxxxxxxx Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx> (cherry picked from commit f0d4ce59f4d48622044933054a0e0cefa91ba15e) Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/display/intel_drrs.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/gpu/drm/i915/display/intel_drrs.c +++ b/drivers/gpu/drm/i915/display/intel_drrs.c @@ -405,6 +405,7 @@ intel_drrs_init(struct intel_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); @@ -416,6 +417,13 @@ intel_drrs_init(struct intel_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;
