drm/amd/display: Skip vendor specific LTTPR w/a outside link training

[Why]
Vendor specific link rate toggle workaround should not be
applied outside of link training scenario, such as when
outputting PHY test pattern.

[How]
Add flag to indicate when link training is occuring.
Make workaround a no-op when flag is not set.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-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_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 86177577f7c76f4571c5da280292f78b563d4ad6..81b0a01615c331f582f89598a23685b9178f817d 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -444,24 +444,26 @@ static void vendor_specific_lttpr_wa_one_two(
        struct dc_link *link,
        const uint8_t rate)
 {
-       uint8_t toggle_rate = 0x0;
+       if (link->apply_vendor_specific_lttpr_link_rate_wa) {
+               uint8_t toggle_rate = 0x0;
 
-       if (rate == 0x6)
-               toggle_rate = 0xA;
-       else
-               toggle_rate = 0x6;
+               if (rate == 0x6)
+                       toggle_rate = 0xA;
+               else
+                       toggle_rate = 0x6;
 
-       if (link->vendor_specific_lttpr_link_rate_wa == rate) {
-               /* W/A for certain LTTPR to reset internal state for link training */
-               core_link_write_dpcd(
-                               link,
-                               DP_LINK_BW_SET,
-                               &toggle_rate,
-                               1);
-       }
+               if (link->vendor_specific_lttpr_link_rate_wa == rate) {
+                       /* W/A for certain LTTPR to reset internal state for link training */
+                       core_link_write_dpcd(
+                                       link,
+                                       DP_LINK_BW_SET,
+                                       &toggle_rate,
+                                       1);
+               }
 
-       /* Store the last attempted link rate for this link */
-       link->vendor_specific_lttpr_link_rate_wa = rate;
+               /* Store the last attempted link rate for this link */
+               link->vendor_specific_lttpr_link_rate_wa = rate;
+       }
 }
 
 static void vendor_specific_lttpr_wa_three(
@@ -2383,10 +2385,12 @@ enum link_training_result dc_link_dp_perform_link_training(
        /* reset previous training states */
        if (link->dc->debug.apply_vendor_specific_lttpr_wa &&
                        (link->chip_caps & EXT_DISPLAY_PATH_CAPS__DP_FIXED_VS_EN) &&
-                       link->lttpr_mode == LTTPR_MODE_TRANSPARENT)
+                       link->lttpr_mode == LTTPR_MODE_TRANSPARENT) {
+               link->apply_vendor_specific_lttpr_link_rate_wa = true;
                vendor_specific_lttpr_wa_four(link, true);
-       else
+       } else {
                dpcd_exit_training_mode(link);
+       }
 
        /* configure link prior to entering training mode */
        dpcd_configure_lttpr_mode(link, &lt_settings);
@@ -2409,10 +2413,12 @@ enum link_training_result dc_link_dp_perform_link_training(
        /* exit training mode */
        if (link->dc->debug.apply_vendor_specific_lttpr_wa &&
                        (link->chip_caps & EXT_DISPLAY_PATH_CAPS__DP_FIXED_VS_EN) &&
-                       link->lttpr_mode == LTTPR_MODE_TRANSPARENT)
+                       link->lttpr_mode == LTTPR_MODE_TRANSPARENT) {
+               link->apply_vendor_specific_lttpr_link_rate_wa = false;
                vendor_specific_lttpr_wa_four(link, (status != LINK_TRAINING_SUCCESS));
-       else
+       } else {
                dpcd_exit_training_mode(link);
+       }
 
        /* switch to video idle */
        if ((status == LINK_TRAINING_SUCCESS) || !skip_video_pattern)

diff --git a/drivers/gpu/drm/amd/display/dc/dc_link.h b/drivers/gpu/drm/amd/display/dc/dc_link.h
index ef123ab2e4b533b215b0cba39430709b7d61f0ee..3d4f5bf049c33e2b33adbf3d3d07d1793908bc62 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dc_link.h
+++ b/drivers/gpu/drm/amd/display/dc/dc_link.h
@@ -188,6 +188,7 @@ struct dc_link {
 
        /* Vendor specific LTTPR workaround variables */
        uint8_t vendor_specific_lttpr_link_rate_wa;
+       bool apply_vendor_specific_lttpr_link_rate_wa;
 
        /* MST record stream using this link */
        struct link_flags {