drm/i915/mtl: Fix SSC selection for MPLLA

Driver does not clear the default SSC for MPLLA. This causes link training
failure when trying to use 10G and 20G rates. Fix the behaviour and enable
ssc only when we really want.

Fixes: 237e7be0bf57 ("drm/i915/mtl: For DP2.0 10G and 20G rates use MPLLA")
Cc: Mika Kahola <mika.kahola@intel.com>
Cc: Clint Taylor <Clinton.A.Taylor@intel.com>
Cc: Khaled Almahallawy <khaled.almahallawy@intel.com>
Cc: Arun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Tested-by: Khaled Almahallawy <khaled.almahallawy@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230616043950.1576836-1-radhakrishna.sripada@intel.com
(cherry picked from commit 7e8d87e2da3b359ad73246233673a84c4dabfa07)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.c b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
index 0600fdcd06ef2a4bd76deec7869e379a302c22cc..719447ce86e7012431f1a7f302c90b78eecc7724 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
+++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
@@ -2435,7 +2435,8 @@ static void intel_program_port_clock_ctl(struct intel_encoder *encoder,
 
        intel_de_rmw(i915, XELPDP_PORT_CLOCK_CTL(encoder->port),
                     XELPDP_LANE1_PHY_CLOCK_SELECT | XELPDP_FORWARD_CLOCK_UNGATE |
-                    XELPDP_DDI_CLOCK_SELECT_MASK | XELPDP_SSC_ENABLE_PLLB, val);
+                    XELPDP_DDI_CLOCK_SELECT_MASK | XELPDP_SSC_ENABLE_PLLA |
+                    XELPDP_SSC_ENABLE_PLLB, val);
 }
 
 static u32 intel_cx0_get_powerdown_update(u8 lane_mask)