drm/amd/display: Increase DPCD read retries

[Why]
Empirical measurement of some monitors that fail to read EDID while
booting shows that the number of retries with a 30ms delay between
tries is as high as 16.

[How]
Increase number of retries to 20.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4672
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit ad1c59ad7cf74ec06e32fe2c330ac1e957222288)
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
index 4d0079b44de12812eac102f980511c54bc9dc23a..eb262ce42e2dc50901f29f86e70282bd3ce4ba19 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
@@ -1691,7 +1691,7 @@ static bool retrieve_link_cap(struct dc_link *link)
        union edp_configuration_cap edp_config_cap;
        union dp_downstream_port_present ds_port = { 0 };
        enum dc_status status = DC_ERROR_UNEXPECTED;
-       uint32_t read_dpcd_retry_cnt = 3;
+       uint32_t read_dpcd_retry_cnt = 20;
        int i;
        struct dp_sink_hw_fw_revision dp_hw_fw_revision;
        const uint32_t post_oui_delay = 30; // 30ms