[PATCH 4.5 082/101] drm/radeon: fix DP mode validation

Greg Kroah-Hartman
2016-05-17T01:28:17Z

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

commit ff0bd441bdfbfa09d05fdba9829a0401a46635c1 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@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -326,8 +326,8 @@ int radeon_dp_get_dp_link_config(struct
}
}
} 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;