From 140ef138db07285b9eecf14ae3ee7c0a407ab93a Mon Sep 17 00:00:00 2001
From: Manasi Navare <manasi.d.navare@intel.com>
Date: Thu, 8 Jun 2017 13:41:03 -0700
Subject: [PATCH] drm/i915/dp: Validate the compliance test link parameters
Git-commit: 140ef138db07285b9eecf14ae3ee7c0a407ab93a
Patch-mainline: v4.14-rc1
References: FATE#322643 bsc#1055900

Validate the compliance test link parameters when the compliance
test dpcd registers are read. Also validate them in compute_config
before using them since the max values might have been reduced
due to link training fallback.

If either the link rate or lane count is invalid, we still bail
from using the test parameters since the combination would not work
and instead use the fallback values.

V2: 
* Added commit message to explain why we still bail when either of
of the params is invalid (Ville Syrjala)
* Add reason for validating in the comment (Jani Nikula)
* Also check if index >= 0 after validating (Jani Nikula)

Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Tested-by: Nathan Ciobanu <nathan.d.ciobanu@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1496954463-18038-2-git-send-email-manasi.d.navare@intel.com
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/intel_dp.c |   34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1690,12 +1690,18 @@ intel_dp_compute_config(struct intel_enc
 	if (intel_dp->compliance.test_type == DP_TEST_LINK_TRAINING) {
 		int index;
 
-		index = intel_dp_rate_index(intel_dp->common_rates,
-					    intel_dp->num_common_rates,
-					    intel_dp->compliance.test_link_rate);
-		if (index >= 0)
-			min_clock = max_clock = index;
-		min_lane_count = max_lane_count = intel_dp->compliance.test_lane_count;
+		/* Validate the compliance test data since max values
+		 * might have changed due to link train fallback.
+		 */
+		if (intel_dp_link_params_valid(intel_dp, intel_dp->compliance.test_link_rate,
+					       intel_dp->compliance.test_lane_count)) {
+			index = intel_dp_rate_index(intel_dp->common_rates,
+						    intel_dp->num_common_rates,
+						    intel_dp->compliance.test_link_rate);
+			if (index >= 0)
+				min_clock = max_clock = index;
+			min_lane_count = max_lane_count = intel_dp->compliance.test_lane_count;
+		}
 	}
 	DRM_DEBUG_KMS("DP link computation with max lane count %i "
 		      "max bw %d pixel clock %iKHz\n",
@@ -3976,8 +3982,7 @@ intel_dp_get_sink_irq_esi(struct intel_d
 static uint8_t intel_dp_autotest_link_training(struct intel_dp *intel_dp)
 {
 	int status = 0;
-	int min_lane_count = 1;
-	int link_rate_index, test_link_rate;
+	int test_link_rate;
 	uint8_t test_lane_count, test_link_bw;
 	/* (DP CTS 1.2)
 	 * 4.3.1.11
@@ -3991,10 +3996,6 @@ static uint8_t intel_dp_autotest_link_tr
 		return DP_TEST_NAK;
 	}
 	test_lane_count &= DP_MAX_LANE_COUNT_MASK;
-	/* Validate the requested lane count */
-	if (test_lane_count < min_lane_count ||
-	    test_lane_count > intel_dp->max_link_lane_count)
-		return DP_TEST_NAK;
 
 	status = drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_LINK_RATE,
 				   &test_link_bw);
@@ -4002,12 +4003,11 @@ static uint8_t intel_dp_autotest_link_tr
 		DRM_DEBUG_KMS("Link Rate read failed\n");
 		return DP_TEST_NAK;
 	}
-	/* Validate the requested link rate */
 	test_link_rate = drm_dp_bw_code_to_link_rate(test_link_bw);
-	link_rate_index = intel_dp_rate_index(intel_dp->common_rates,
-					      intel_dp->num_common_rates,
-					      test_link_rate);
-	if (link_rate_index < 0)
+
+	/* Validate the requested link rate and lane count */
+	if (!intel_dp_link_params_valid(intel_dp, test_link_rate,
+					test_lane_count))
 		return DP_TEST_NAK;
 
 	intel_dp->compliance.test_lane_count = test_lane_count;