drm/i915: Skip vswing programming for TBT

commit eaf5bfe upstream.

In thunderbolt mode the PHY is owned by the thunderbolt controller.
We are not supposed to touch it. So skip the vswing programming
as well (we already skipped the other steps not applicable to TBT).

Touching this stuff could supposedly interfere with the PHY
programming done by the thunderbolt controller.

Cc: stable@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210128155948.13678-1-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>
(cherry picked from commit f8c6b61)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: vsyrjala

drivers/gpu/drm/i915/display/intel_ddi.c

@@ -2597,6 +2597,9 @@ static void icl_mg_phy_ddi_vswing_sequence(struct intel_encoder *encoder,
 	u32 n_entries, val;
 	int ln, rate = 0;
 
+	if (enc_to_dig_port(encoder)->tc_mode == TC_PORT_TBT_ALT)
+		return;
+
 	if (type != INTEL_OUTPUT_HDMI) {
 		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 
@@ -2741,6 +2744,9 @@ tgl_dkl_phy_ddi_vswing_sequence(struct intel_encoder *encoder, int link_clock,
 	u32 n_entries, val, ln, dpcnt_mask, dpcnt_val;
 	int rate = 0;
 
+	if (enc_to_dig_port(encoder)->tc_mode == TC_PORT_TBT_ALT)
+		return;
+
 	if (type != INTEL_OUTPUT_HDMI) {
 		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);