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

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>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
index 21aacc1f45c1fd7afded7f6088c8a365e9005224..bf731e9f643e9ecddd367034179fae6a40d294ce 100644 (file)
--- 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_link_config(struct drm_connector *connector
        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;