By the specification the 0xF0000 - 0xF02FF range is only valid if the
LTTPR revision at 0xF0000 is at least 1.4. Disable the LTTPR support
otherwise.
Fixes: 7b2a4ab8b0ef ("drm/i915: Switch to LTTPR transparent mode link training")
Cc: <stable@xxxxxxxxxxxxxxx> # v5.11
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20210317184901.4029798-4-imre.deak@xxxxxxxxx
(cherry picked from commit 1663ad4936e0679443a315fe342f99636a2420dd)
---
.../gpu/drm/i915/display/intel_dp_link_training.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
index c10e81a3d64f..be6ac0dd846e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -99,17 +99,23 @@ static bool intel_dp_read_lttpr_common_caps(struct intel_dp *intel_dp)
return false;
if (drm_dp_read_lttpr_common_caps(&intel_dp->aux,
- intel_dp->lttpr_common_caps) < 0) {
- intel_dp_reset_lttpr_common_caps(intel_dp);
- return false;
- }
+ intel_dp->lttpr_common_caps) < 0)
+ goto reset_caps;
drm_dbg_kms(&dp_to_i915(intel_dp)->drm,
"LTTPR common capabilities: %*ph\n",
(int)sizeof(intel_dp->lttpr_common_caps),
intel_dp->lttpr_common_caps);
+ /* The minimum value of LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV is 1.4 */
+ if (intel_dp->lttpr_common_caps[0] < 0x14)
+ goto reset_caps;
+
return true;
+
+reset_caps:
+ intel_dp_reset_lttpr_common_caps(intel_dp);
+ return false;
}
static bool
