From: Wenjing Liu <wenjing....@amd.com>

[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.lip...@amd.com>
Signed-off-by: Wenjing Liu <wenjing....@amd.com>
Reviewed-by: George Shen <george.s...@amd.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

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 f1c9ee53ac67..5d9460e0dbab 100644
--- 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;
-- 
2.25.1

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