drm/msm/dp: Prepare for link training per-segment for LTTPRs

Per-segment link training requires knowing the number of LTTPRs
(if any) present. Store the count during LTTPRs' initialization.

Fixes: 72d0af4accd9 ("drm/msm/dp: Add support for LTTPR handling")
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Aleksandrs Vinarskis <alex.vinarskis@gmail.com>
Tested-by: Jessica Zhang <quic_jesszhan@quicinc.com> # SA8775P
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Rob Clark <robdclark@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/652306/
Link: https://lore.kernel.org/r/20250507230113.14270-4-alex.vinarskis@gmail.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index ba08350cd9c5918f2d83d1c2b5766d86edc690a7..386c4669c831ebc0d4b567086cde8d818bcdd095 100644 (file)
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -360,16 +360,21 @@ static int msm_dp_display_send_hpd_notification(struct msm_dp_display_private *d
        return 0;
 }
 
-static void msm_dp_display_lttpr_init(struct msm_dp_display_private *dp, u8 *dpcd)
+static int msm_dp_display_lttpr_init(struct msm_dp_display_private *dp, u8 *dpcd)
 {
-       int rc;
+       int rc, lttpr_count;
 
        if (drm_dp_read_lttpr_common_caps(dp->aux, dpcd, dp->link->lttpr_common_caps))
-               return;
+               return 0;
 
-       rc = drm_dp_lttpr_init(dp->aux, drm_dp_lttpr_count(dp->link->lttpr_common_caps));
-       if (rc)
+       lttpr_count = drm_dp_lttpr_count(dp->link->lttpr_common_caps);
+       rc = drm_dp_lttpr_init(dp->aux, lttpr_count);
+       if (rc) {
                DRM_ERROR("failed to set LTTPRs transparency mode, rc=%d\n", rc);
+               return 0;
+       }
+
+       return lttpr_count;
 }
 
 static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
@@ -383,7 +388,7 @@ static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
        if (rc)
                goto end;
 
-       msm_dp_display_lttpr_init(dp, dpcd);
+       dp->link->lttpr_count = msm_dp_display_lttpr_init(dp, dpcd);
 
        rc = msm_dp_panel_read_sink_caps(dp->panel, connector);
        if (rc)

diff --git a/drivers/gpu/drm/msm/dp/dp_link.h b/drivers/gpu/drm/msm/dp/dp_link.h
index c47d75cfc720c9fac31e6eb3e82601a9e922ce51..ba47c6d19fbfacfc58031263e4a2f5a6d9c2c229 100644 (file)
--- a/drivers/gpu/drm/msm/dp/dp_link.h
+++ b/drivers/gpu/drm/msm/dp/dp_link.h
@@ -62,6 +62,7 @@ struct msm_dp_link_phy_params {
 
 struct msm_dp_link {
        u8 lttpr_common_caps[DP_LTTPR_COMMON_CAP_SIZE];
+       int lttpr_count;
 
        u32 sink_request;
        u32 test_response;