[PATCH v2 drm-dp 02/10] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq

[Yongbang Shi]

From: Baihan Li <libai...@huawei.com>

The debouncing when HPD pulled out still remains sometimes, 200ms still can
not ensure helper_detect() is correct. So add more checks and
hibmc_dp_link_training0() in detect_ctx().

Fixes: 3c7623fb5bb6 ("drm/hisilicon/hibmc: Enable this hot plug detect of irq 
feature")
Signed-off-by: Baihan Li <libai...@huawei.com>
Signed-off-by: Yongbang Shi <shiyongb...@huawei.com>
---
ChangeLog:
v1 -> v2:
  - don't use the flag, and use more checks in detect_ctx(), suggested by 
Dmitry Baryshkov.
  - delete if (dev->registered), suggested by Dmitry Baryshkov.
---
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c    | 24 +++++++++++++++----
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h    |  2 ++
 .../gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c    | 19 +++++++++++----
 3 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c 
b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
index 8f0daec7d174..8a965e143012 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
@@ -238,19 +238,33 @@ void hibmc_dp_display_en(struct hibmc_dp *dp, bool enable)
        msleep(50);
 }
 
-int hibmc_dp_mode_set(struct hibmc_dp *dp, struct drm_display_mode *mode)
+int hibmc_dp_detect_link(struct hibmc_dp *dp)
 {
        struct hibmc_dp_dev *dp_dev = dp->dp_dev;
-       int ret;
+       int ret = 0;
+
+       mutex_lock(&dp->link_train_mutex);
 
        if (!dp_dev->link.status.channel_equalized) {
                ret = hibmc_dp_link_training(dp_dev);
-               if (ret) {
+               if (ret)
                        drm_err(dp->drm_dev, "dp link training failed, ret: 
%d\n", ret);
-                       return ret;
-               }
        }
 
+       mutex_unlock(&dp->link_train_mutex);
+
+       return ret;
+}
+
+int hibmc_dp_mode_set(struct hibmc_dp *dp, struct drm_display_mode *mode)
+{
+       struct hibmc_dp_dev *dp_dev = dp->dp_dev;
+       int ret;
+
+       ret = hibmc_dp_detect_link(dp);
+       if (ret)
+               return ret;
+
        hibmc_dp_display_en(dp, false);
        hibmc_dp_link_cfg(dp_dev, mode);
 
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h 
b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
index 665f5b166dfb..9b45e88e47e4 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
@@ -50,9 +50,11 @@ struct hibmc_dp {
        struct drm_dp_aux aux;
        struct hibmc_dp_cbar_cfg cfg;
        u32 irq_status;
+       struct mutex link_train_mutex; /* link training mutex */
 };
 
 int hibmc_dp_hw_init(struct hibmc_dp *dp);
+int hibmc_dp_detect_link(struct hibmc_dp *dp);
 int hibmc_dp_mode_set(struct hibmc_dp *dp, struct drm_display_mode *mode);
 void hibmc_dp_display_en(struct hibmc_dp *dp, bool enable);
 void hibmc_dp_set_cbar(struct hibmc_dp *dp, const struct hibmc_dp_cbar_cfg 
*cfg);
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c 
b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
index d06832e62e96..c0de796225b7 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
@@ -34,9 +34,19 @@ static int hibmc_dp_connector_get_modes(struct drm_connector 
*connector)
 static int hibmc_dp_detect(struct drm_connector *connector,
                           struct drm_modeset_acquire_ctx *ctx, bool force)
 {
-       mdelay(200);
+       struct hibmc_dp *dp = to_hibmc_dp(connector);
+
+       if (!(dp->irq_status & DP_MASKED_SINK_HPD_PLUG_INT))
+               return connector_status_disconnected;
+
+       if (drm_connector_helper_detect_from_ddc(connector, ctx, force) !=
+           connector_status_connected)
+               return connector_status_disconnected;
 
-       return drm_connector_helper_detect_from_ddc(connector, ctx, force);
+       if (hibmc_dp_detect_link(dp))
+               return connector_status_connected;
+
+       return connector_status_disconnected;
 }
 
 static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
@@ -128,8 +138,7 @@ irqreturn_t hibmc_dp_hpd_isr(int irq, void *arg)
                hibmc_dp_reset_link(&priv->dp);
        }
 
-       if (dev->registered)
-               drm_connector_helper_hpd_irq_event(&priv->dp.connector);
+       drm_connector_helper_hpd_irq_event(&priv->dp.connector);
 
        drm_dev_exit(idx);
 
@@ -178,5 +187,7 @@ int hibmc_dp_init(struct hibmc_drm_private *priv)
 
        connector->polled = DRM_CONNECTOR_POLL_HPD;
 
+       mutex_init(&dp->link_train_mutex);
+
        return 0;
 }
-- 
2.33.0