linux-kernel - [PATCH 4.5 083/101] drm/amdgpu: fix DP mode validation

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Date:	Mon, 16 May 2016 18:21:28 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Alex Deucher <alexander.deucher@....com>
Subject: [PATCH 4.5 083/101] drm/amdgpu: fix DP mode validation

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit c47b9e0944e483309d66c807d650ac8b8ceafb57 upstream.

Switch the order of the loops to walk the rates on the top
so we exhaust all DP 1.1 rate/lane combinations before trying
DP 1.2 rate/lane combos.

This avoids selecting rates that are supported by the monitor,
but not the connector leading to valid modes getting rejected.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=95206

Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/amd/amdgpu/atombios_dp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
+++ b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
@@ -276,8 +276,8 @@ static int amdgpu_atombios_dp_get_dp_lin
 			}
 		}
 	} 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++) {
+		for (i = 0; i < ARRAY_SIZE(link_rates) && link_rates[i] <= max_link_rate; i++) {
+			for (lane_num = 1; lane_num <= max_lane_num; lane_num <<= 1) {
 				max_pix_clock = (lane_num * link_rates[i] * 8) / bpp;
 				if (max_pix_clock >= pix_clock) {
 					*dp_lanes = lane_num;