drm/amd/display: update conditions to do dfp cap ext validation

[why]
According to DP specs dfp cap ext validation is only for branch
device withou 128b/132b channel coding support and
downstream of the branch device doesn't have compression.
Therefore we are adding conditions to only do dfp cap
extension validation for branch devcie supporting 8b/10b
channel coding only and it has no DSC passthrough capability.

Acked-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Reviewed-by: George Shen <george.shen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index f1c9ee5..5d9460e 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -2606,7 +2606,9 @@ static bool dp_active_dongle_validate_timing(
 #if defined(CONFIG_DRM_AMD_DC_DCN)
        }
 
-       if (dongle_caps->dfp_cap_ext.supported) {
+       if (dpcd_caps->channel_coding_cap.bits.DP_128b_132b_SUPPORTED == 0 &&
+                       dpcd_caps->dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_PASSTHROUGH_SUPPORT == 0 &&
+                       dongle_caps->dfp_cap_ext.supported) {
 
                if (dongle_caps->dfp_cap_ext.max_pixel_rate_in_mps < (timing->pix_clk_100hz / 10000))
                        return false;