[SRU][E][PATCH 27/52] drm/i915: WARN about invalid lane reversal in TBT-alt/DP-alt modes

You-Sheng Yang vicamo.yang at canonical.com
Wed Apr 22 14:11:50 UTC 2020

From: Imre Deak <imre.deak at intel.com>

BugLink: https://bugs.launchpad.net/bugs/1868936

Lane reversal happens only in the FIA module for TBT-alt/DP-alt mode, so
WARN if lane reversal is attempted at a different level. See the
BSpec DDI_BUF_CTL register description.

Cc: Manasi Navare <manasi.d.navare at intel.com>
Cc: José Roberto de Souza <jose.souza at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Signed-off-by: Imre Deak <imre.deak at intel.com>
Reviewed-by: José Roberto de Souza <jose.souza at intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190628143635.22066-24-imre.deak@intel.com
(cherry picked from commit 3ee2771e47b038624d68aa051d78ff8558c260b9)
Signed-off-by: You-Sheng Yang <vicamo.yang at canonical.com>
 drivers/gpu/drm/i915/display/intel_ddi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 839867ea5b01..5f3fd8907bdc 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -3604,6 +3604,8 @@ static void intel_ddi_set_fia_lane_count(struct intel_encoder *encoder,
 	u32 val = I915_READ(PORT_TX_DFLEXDPMLE1);
 	bool lane_reversal = dig_port->saved_port_bits & DDI_BUF_PORT_REVERSAL;
+	WARN_ON(lane_reversal && dig_port->tc_mode != TC_PORT_LEGACY);
 	val &= ~DFLEXDPMLE1_DPMLETC_MASK(tc_port);
 	switch (pipe_config->lane_count) {
 	case 1:

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