drm/msm/dp: do not reinitialize phy unless retry during link training

[ Upstream commit 0c1a2e69bcb506f48ebf94bd199bab0b93f66da2 ]

DP PHY re-initialization done using dp_ctrl_reinitialize_mainlink() will
cause PLL unlocked initially and then PLL gets locked at the end of
initialization. PLL_UNLOCKED interrupt will fire during this time if the
interrupt mask is enabled.

However currently DP driver link training implementation incorrectly
re-initializes PHY unconditionally during link training as the PHY was
already configured in dp_ctrl_enable_mainlink_clocks().

Fix this by re-initializing the PHY only if the previous link training
failed.

[drm:dp_aux_isr] *ERROR* Unexpected DP AUX IRQ 0x01000000 when not busy

Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/30
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Tested-by: Abhinav Kumar <quic_abhinavk@quicinc.com> # sc7280
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/551847/
Link: https://lore.kernel.org/r/1691533190-19335-1-git-send-email-quic_khsieh@quicinc.com
[quic_abhinavk@quicinc.com: added line break in commit text]
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index dd26ca651a0544ba349df14025157fdeacfa5845..103eef9f059a0bb9111731c7c847b64b0244b1d7 100644 (file)
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1711,13 +1711,6 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
                return rc;
 
        while (--link_train_max_retries) {
-               rc = dp_ctrl_reinitialize_mainlink(ctrl);
-               if (rc) {
-                       DRM_ERROR("Failed to reinitialize mainlink. rc=%d\n",
-                                       rc);
-                       break;
-               }
-
                training_step = DP_TRAINING_NONE;
                rc = dp_ctrl_setup_main_link(ctrl, &training_step);
                if (rc == 0) {
@@ -1769,6 +1762,12 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
                        /* stop link training before start re training  */
                        dp_ctrl_clear_training_pattern(ctrl);
                }
+
+               rc = dp_ctrl_reinitialize_mainlink(ctrl);
+               if (rc) {
+                       DRM_ERROR("Failed to reinitialize mainlink. rc=%d\n", rc);
+                       break;
+               }
        }
 
        if (ctrl->link->sink_request & DP_TEST_LINK_PHY_TEST_PATTERN)