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drm/i915: Disable DRRS on IVB/HSW port != A

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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@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220128103757.22461-11-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit f0d4ce59f4)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
This commit is contained in:
Ville Syrjälä 2022-01-28 12:37:50 +02:00 committed by Tvrtko Ursulin
parent eb48d42198
commit ee59792c97
1 changed files with 8 additions and 0 deletions
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8
drivers/gpu/drm/i915/display/intel_drrs.c
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@ -405,6 +405,7 @@ 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);
@ -416,6 +417,13 @@ 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;