Patch "drm/amdgpu/dp: add back special handling for NUTMEG" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    drm/amdgpu/dp: add back special handling for NUTMEG

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amdgpu-dp-add-back-special-handling-for-nutmeg.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 02d27234759dc4fe14a880ec1e1dee108cb0b503 Mon Sep 17 00:00:00 2001
From: Alex Deucher <alexander.deucher@amd.com>
Date: Thu, 3 Mar 2016 19:34:28 -0500
Subject: drm/amdgpu/dp: add back special handling for NUTMEG
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

From: Alex Deucher <alexander.deucher@amd.com>

commit 02d27234759dc4fe14a880ec1e1dee108cb0b503 upstream.

When I fixed the dp rate selection in:
3b73b168cffd9c392584d3f665021fa2190f8612
drm/amdgpu: fix dp link rate selection (v2)
I accidently dropped the special handling for NUTMEG
DP bridge chips.  They require a fixed link rate.

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Ken Wang <Qingqing.Wang@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/amd/amdgpu/atombios_dp.c |   20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
+++ b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
@@ -265,15 +265,27 @@ static int amdgpu_atombios_dp_get_dp_lin
 	unsigned max_lane_num = drm_dp_max_lane_count(dpcd);
 	unsigned lane_num, i, max_pix_clock;
 
-	for (lane_num = 1; lane_num <= max_lane_num; lane_num <<= 1) {
-		for (i = 0; i < ARRAY_SIZE(link_rates) && link_rates[i] <= max_link_rate; i++) {
-			max_pix_clock = (lane_num * link_rates[i] * 8) / bpp;
+	if (amdgpu_connector_encoder_get_dp_bridge_encoder_id(connector) ==
+	    ENCODER_OBJECT_ID_NUTMEG) {
+		for (lane_num = 1; lane_num <= max_lane_num; lane_num <<= 1) {
+			max_pix_clock = (lane_num * 270000 * 8) / bpp;
 			if (max_pix_clock >= pix_clock) {
 				*dp_lanes = lane_num;
-				*dp_rate = link_rates[i];
+				*dp_rate = 270000;
 				return 0;
 			}
 		}
+	} else {
+		for (lane_num = 1; lane_num <= max_lane_num; lane_num <<= 1) {
+			for (i = 0; i < ARRAY_SIZE(link_rates) && link_rates[i] <= max_link_rate; i++) {
+				max_pix_clock = (lane_num * link_rates[i] * 8) / bpp;
+				if (max_pix_clock >= pix_clock) {
+					*dp_lanes = lane_num;
+					*dp_rate = link_rates[i];
+					return 0;
+				}
+			}
+		}
 	}
 
 	return -EINVAL;


Patches currently in stable-queue which might be from alexander.deucher@amd.com are

queue-4.4/drm-amdgpu-fix-dp-mode-validation.patch
queue-4.4/drm-radeon-fix-dp-mode-validation.patch
queue-4.4/drm-amdgpu-dp-add-back-special-handling-for-nutmeg.patch
queue-4.4/drm-radeon-dp-add-back-special-handling-for-nutmeg.patch