Commit 1663ad49 authored by Imre Deak's avatar Imre Deak
Browse files

drm/i915: Disable LTTPR support when the LTTPR rev < 1.4 



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: 7b2a4ab8 ("drm/i915: Switch to LTTPR transparent mode link training")
Cc: <stable@vger.kernel.org> # v5.11
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: default avatarImre Deak <imre.deak@intel.com>
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210317184901.4029798-4-imre.deak@intel.com
parent 264613b4

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

+10 −4
Original line number Diff line number Diff line
@@ -100,17 +100,23 @@ 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