[0566/1094] drm/i915: use lane count and link rate from VBT as minimums for eDP

Commit Message

Dheeraj Jamwal Oct. 21, 2014, 10:52 a.m. UTC

From: Jani Nikula <[e-mail]>

Most likely the minimums for both should be enough for enabling the
native resolution on the eDP, and we'll end up using the predetermined
optimal link config for the panel.

v2: Add debug prints.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73539
Tested-by: Markus Blank-Burian <[e-mail]>
Reviewed-by: Damien Lespiau <[e-mail]>
Signed-off-by: Jani Nikula <[e-mail]>
(cherry picked from commit 56071a207602a451f0c46d3dcc8379b59ef576e2)

Signed-off-by: Dheeraj Jamwal <[e-mail]>
---
 drivers/gpu/drm/i915/intel_dp.c |   30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

Patch

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 115662c2..8233f2a 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -767,8 +767,10 @@  intel_dp_compute_config(struct intel_encoder *encoder,
 	struct intel_crtc *intel_crtc = encoder->new_crtc;
 	struct intel_connector *intel_connector = intel_dp->attached_connector;
 	int lane_count, clock;
+	int min_lane_count = 1;
 	int max_lane_count = intel_dp_max_lane_count(intel_dp);
 	/* Conveniently, the link BW constants become indices with a shift...*/
+	int min_clock = 0;
 	int max_clock = intel_dp_max_link_bw(intel_dp) >> 3;
 	int bpp, mode_rate;
 	static int bws[] = { DP_LINK_BW_1_62, DP_LINK_BW_2_7, DP_LINK_BW_5_4 };
@@ -801,19 +803,33 @@  intel_dp_compute_config(struct intel_encoder *encoder,
 	/* Walk through all bpp values. Luckily they're all nicely spaced with 2
 	 * bpc in between. */
 	bpp = pipe_config->pipe_bpp;
-	if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp &&
-	    dev_priv->vbt.edp_bpp < bpp) {
-		DRM_DEBUG_KMS("clamping bpp for eDP panel to BIOS-provided %i\n",
-			      dev_priv->vbt.edp_bpp);
-		bpp = dev_priv->vbt.edp_bpp;
+	if (is_edp(intel_dp)) {
+		if (dev_priv->vbt.edp_bpp && dev_priv->vbt.edp_bpp < bpp) {
+			DRM_DEBUG_KMS("clamping bpp for eDP panel to BIOS-provided %i\n",
+				      dev_priv->vbt.edp_bpp);
+			bpp = dev_priv->vbt.edp_bpp;
+		}
+
+		if (dev_priv->vbt.edp_lanes) {
+			min_lane_count = min(dev_priv->vbt.edp_lanes,
+					     max_lane_count);
+			DRM_DEBUG_KMS("using min %u lanes per VBT\n",
+				      min_lane_count);
+		}
+
+		if (dev_priv->vbt.edp_rate) {
+			min_clock = min(dev_priv->vbt.edp_rate >> 3, max_clock);
+			DRM_DEBUG_KMS("using min %02x link bw per VBT\n",
+				      bws[min_clock]);
+		}
 	}
 
 	for (; bpp >= 6*3; bpp -= 2*3) {
 		mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock,
 						   bpp);
 
-		for (lane_count = 1; lane_count <= max_lane_count; lane_count <<= 1) {
-			for (clock = 0; clock <= max_clock; clock++) {
+		for (lane_count = min_lane_count; lane_count <= max_lane_count; lane_count <<= 1) {
+			for (clock = min_clock; clock <= max_clock; clock++) {
 				link_clock = drm_dp_bw_code_to_link_rate(bws[clock]);
 				link_avail = intel_dp_max_data_rate(link_clock,
 								    lane_count);