During suspend, dp host controller and hpd block are disabled due to
both ahb and aux clock are disabled. Therefore hpd plug/unplug interrupts
will not be generated. At dp_pm_resume(), reinitialize both dp host
controller and hpd block so that hpd plug/unplug interrupts will be
generated and handled by driver so that hpd connection state is updated
correctly. This patch will fix link training flaky issues.

Changes in v2:
-- use container_of to cast correct dp_display_private pointer
   at both dp_pm_suspend() and dp_pm_resume().

Changes in v3:
-- replace hpd_state atomic_t  with u32
-- Add more information to commit message.

Signed-off-by: Kuogee Hsieh <khs...@codeaurora.org>
---
 drivers/gpu/drm/msm/dp/dp_catalog.c |  13 ++++
 drivers/gpu/drm/msm/dp/dp_catalog.h |   1 +
 drivers/gpu/drm/msm/dp/dp_display.c | 117 +++++++++++++---------------
 drivers/gpu/drm/msm/dp/dp_reg.h     |   2 +
 4 files changed, 72 insertions(+), 61 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c 
b/drivers/gpu/drm/msm/dp/dp_catalog.c
index b15b4ce4ba35..4963bfe6a472 100644
--- a/drivers/gpu/drm/msm/dp/dp_catalog.c
+++ b/drivers/gpu/drm/msm/dp/dp_catalog.c
@@ -572,6 +572,19 @@ void dp_catalog_ctrl_hpd_config(struct dp_catalog 
*dp_catalog)
        dp_write_aux(catalog, REG_DP_DP_HPD_CTRL, DP_DP_HPD_CTRL_HPD_EN);
 }
 
+u32 dp_catalog_hpd_get_state_status(struct dp_catalog *dp_catalog)
+{
+       struct dp_catalog_private *catalog = container_of(dp_catalog,
+                               struct dp_catalog_private, dp_catalog);
+       u32 status;
+
+       status = dp_read_aux(catalog, REG_DP_DP_HPD_INT_STATUS);
+       status >>= DP_DP_HPD_STATE_STATUS_BITS_SHIFT;
+       status &= DP_DP_HPD_STATE_STATUS_BITS_MASK;
+
+       return status;
+}
+
 u32 dp_catalog_hpd_get_intr_status(struct dp_catalog *dp_catalog)
 {
        struct dp_catalog_private *catalog = container_of(dp_catalog,
diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.h 
b/drivers/gpu/drm/msm/dp/dp_catalog.h
index 4b7666f1fe6f..6d257dbebf29 100644
--- a/drivers/gpu/drm/msm/dp/dp_catalog.h
+++ b/drivers/gpu/drm/msm/dp/dp_catalog.h
@@ -97,6 +97,7 @@ void dp_catalog_ctrl_enable_irq(struct dp_catalog 
*dp_catalog, bool enable);
 void dp_catalog_hpd_config_intr(struct dp_catalog *dp_catalog,
                        u32 intr_mask, bool en);
 void dp_catalog_ctrl_hpd_config(struct dp_catalog *dp_catalog);
+u32 dp_catalog_hpd_get_state_status(struct dp_catalog *dp_catalog);
 u32 dp_catalog_hpd_get_intr_status(struct dp_catalog *dp_catalog);
 void dp_catalog_ctrl_phy_reset(struct dp_catalog *dp_catalog);
 int dp_catalog_ctrl_update_vx_px(struct dp_catalog *dp_catalog, u8 v_level,
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c 
b/drivers/gpu/drm/msm/dp/dp_display.c
index e175aa3fd3a9..fd16e12ab2f8 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -108,14 +108,12 @@ struct dp_display_private {
        /* event related only access by event thread */
        struct mutex event_mutex;
        wait_queue_head_t event_q;
-       atomic_t hpd_state;
+       u32 hpd_state;
        u32 event_pndx;
        u32 event_gndx;
        struct dp_event event_list[DP_EVENT_Q_MAX];
        spinlock_t event_lock;
 
-       struct completion resume_comp;
-
        struct dp_audio *audio;
 };
 
@@ -490,7 +488,7 @@ static int dp_hpd_plug_handle(struct dp_display_private 
*dp, u32 data)
 
        mutex_lock(&dp->event_mutex);
 
-       state =  atomic_read(&dp->hpd_state);
+       state =  dp->hpd_state;
        if (state == ST_SUSPEND_PENDING) {
                mutex_unlock(&dp->event_mutex);
                return 0;
@@ -508,17 +506,14 @@ static int dp_hpd_plug_handle(struct dp_display_private 
*dp, u32 data)
                return 0;
        }
 
-       if (state == ST_SUSPENDED)
-               tout = DP_TIMEOUT_NONE;
-
-       atomic_set(&dp->hpd_state, ST_CONNECT_PENDING);
+       dp->hpd_state = ST_CONNECT_PENDING;
 
        hpd->hpd_high = 1;
 
        ret = dp_display_usbpd_configure_cb(&dp->pdev->dev);
        if (ret) {      /* failed */
                hpd->hpd_high = 0;
-               atomic_set(&dp->hpd_state, ST_DISCONNECTED);
+               dp->hpd_state = ST_DISCONNECTED;
        }
 
        /* start sanity checking */
@@ -539,10 +534,10 @@ static int dp_connect_pending_timeout(struct 
dp_display_private *dp, u32 data)
 
        mutex_lock(&dp->event_mutex);
 
-       state =  atomic_read(&dp->hpd_state);
+       state = dp->hpd_state;
        if (state == ST_CONNECT_PENDING) {
                dp_display_enable(dp, 0);
-               atomic_set(&dp->hpd_state, ST_CONNECTED);
+               dp->hpd_state = ST_CONNECTED;
        }
 
        mutex_unlock(&dp->event_mutex);
@@ -567,7 +562,7 @@ static int dp_hpd_unplug_handle(struct dp_display_private 
*dp, u32 data)
 
        mutex_lock(&dp->event_mutex);
 
-       state = atomic_read(&dp->hpd_state);
+       state = dp->hpd_state;
        if (state == ST_SUSPEND_PENDING) {
                mutex_unlock(&dp->event_mutex);
                return 0;
@@ -585,7 +580,7 @@ static int dp_hpd_unplug_handle(struct dp_display_private 
*dp, u32 data)
                return 0;
        }
 
-       atomic_set(&dp->hpd_state, ST_DISCONNECT_PENDING);
+       dp->hpd_state = ST_DISCONNECT_PENDING;
 
        /* disable HPD plug interrupt until disconnect is done */
        dp_catalog_hpd_config_intr(dp->catalog, DP_DP_HPD_PLUG_INT_MASK
@@ -620,10 +615,10 @@ static int dp_disconnect_pending_timeout(struct 
dp_display_private *dp, u32 data
 
        mutex_lock(&dp->event_mutex);
 
-       state =  atomic_read(&dp->hpd_state);
+       state =  dp->hpd_state;
        if (state == ST_DISCONNECT_PENDING) {
                dp_display_disable(dp, 0);
-               atomic_set(&dp->hpd_state, ST_DISCONNECTED);
+               dp->hpd_state = ST_DISCONNECTED;
        }
 
        mutex_unlock(&dp->event_mutex);
@@ -638,7 +633,7 @@ static int dp_irq_hpd_handle(struct dp_display_private *dp, 
u32 data)
        mutex_lock(&dp->event_mutex);
 
        /* irq_hpd can happen at either connected or disconnected state */
-       state =  atomic_read(&dp->hpd_state);
+       state =  dp->hpd_state;
        if (state == ST_SUSPEND_PENDING) {
                mutex_unlock(&dp->event_mutex);
                return 0;
@@ -798,8 +793,6 @@ static int dp_display_enable(struct dp_display_private *dp, 
u32 data)
        if (!rc)
                dp_display->power_on = true;
 
-       /* complete resume_comp regardless it is armed or not */
-       complete(&dp->resume_comp);
        return rc;
 }
 
@@ -1151,9 +1144,6 @@ static int dp_display_probe(struct platform_device *pdev)
        }
 
        mutex_init(&dp->event_mutex);
-
-       init_completion(&dp->resume_comp);
-
        g_dp_display = &dp->dp_display;
 
        /* Store DP audio handle inside DP display */
@@ -1189,20 +1179,50 @@ static int dp_display_remove(struct platform_device 
*pdev)
 
 static int dp_pm_resume(struct device *dev)
 {
+       struct platform_device *pdev = to_platform_device(dev);
+       struct msm_dp *dp_display = platform_get_drvdata(pdev);
+       struct dp_display_private *dp;
+       u32 status;
+
+       dp = container_of(dp_display, struct dp_display_private, dp_display);
+
+       mutex_lock(&dp->event_mutex);
+
+       dp_display_host_init(dp);
+
+       dp_catalog_ctrl_hpd_config(dp->catalog);
+
+       status = dp_catalog_hpd_get_state_status(dp->catalog);
+
+       if (status) {
+               dp->dp_display.is_connected = true;
+       } else {
+               dp->dp_display.is_connected = false;
+               /* make sure next resume host_init be called */
+               dp->core_initialized = false;
+       }
+
+       mutex_unlock(&dp->event_mutex);
+
        return 0;
 }
 
 static int dp_pm_suspend(struct device *dev)
 {
        struct platform_device *pdev = to_platform_device(dev);
-       struct dp_display_private *dp = platform_get_drvdata(pdev);
+       struct msm_dp *dp_display = platform_get_drvdata(pdev);
+       struct dp_display_private *dp;
 
-       if (!dp) {
-               DRM_ERROR("DP driver bind failed. Invalid driver data\n");
-               return -EINVAL;
-       }
+       dp = container_of(dp_display, struct dp_display_private, dp_display);
 
-       atomic_set(&dp->hpd_state, ST_SUSPENDED);
+       mutex_lock(&dp->event_mutex);
+
+       if (dp_display->power_on == true)
+               dp_display_disable(dp, 0);
+
+       dp->hpd_state = ST_SUSPENDED;
+
+       mutex_unlock(&dp->event_mutex);
 
        return 0;
 }
@@ -1317,19 +1337,6 @@ int msm_dp_modeset_init(struct msm_dp *dp_display, 
struct drm_device *dev,
        return 0;
 }
 
-static int dp_display_wait4resume_done(struct dp_display_private *dp)
-{
-       int ret = 0;
-
-       reinit_completion(&dp->resume_comp);
-       if (!wait_for_completion_timeout(&dp->resume_comp,
-                               WAIT_FOR_RESUME_TIMEOUT_JIFFIES)) {
-               DRM_ERROR("wait4resume_done timedout\n");
-               ret = -ETIMEDOUT;
-       }
-       return ret;
-}
-
 int msm_dp_display_enable(struct msm_dp *dp, struct drm_encoder *encoder)
 {
        int rc = 0;
@@ -1344,6 +1351,8 @@ int msm_dp_display_enable(struct msm_dp *dp, struct 
drm_encoder *encoder)
 
        mutex_lock(&dp_display->event_mutex);
 
+       dp_del_event(dp_display, EV_CONNECT_PENDING_TIMEOUT);
+
        rc = dp_display_set_mode(dp, &dp_display->dp_mode);
        if (rc) {
                DRM_ERROR("Failed to perform a mode set, rc=%d\n", rc);
@@ -1358,15 +1367,7 @@ int msm_dp_display_enable(struct msm_dp *dp, struct 
drm_encoder *encoder)
                return rc;
        }
 
-       state =  atomic_read(&dp_display->hpd_state);
-       if (state == ST_SUSPENDED) {
-               /* start link training */
-               dp_add_event(dp_display, EV_HPD_PLUG_INT, 0, 0);
-               mutex_unlock(&dp_display->event_mutex);
-
-               /* wait until dp interface is up */
-               goto resume_done;
-       }
+       state =  dp_display->hpd_state;
 
        dp_display_enable(dp_display, 0);
 
@@ -1377,21 +1378,15 @@ int msm_dp_display_enable(struct msm_dp *dp, struct 
drm_encoder *encoder)
                dp_display_unprepare(dp);
        }
 
-       dp_del_event(dp_display, EV_CONNECT_PENDING_TIMEOUT);
-
        if (state == ST_SUSPEND_PENDING)
                dp_add_event(dp_display, EV_IRQ_HPD_INT, 0, 0);
 
        /* completed connection */
-       atomic_set(&dp_display->hpd_state, ST_CONNECTED);
+       dp_display->hpd_state = ST_CONNECTED;
 
        mutex_unlock(&dp_display->event_mutex);
 
        return rc;
-
-resume_done:
-       dp_display_wait4resume_done(dp_display);
-       return rc;
 }
 
 int msm_dp_display_pre_disable(struct msm_dp *dp, struct drm_encoder *encoder)
@@ -1415,20 +1410,20 @@ int msm_dp_display_disable(struct msm_dp *dp, struct 
drm_encoder *encoder)
 
        mutex_lock(&dp_display->event_mutex);
 
+       dp_del_event(dp_display, EV_DISCONNECT_PENDING_TIMEOUT);
+
        dp_display_disable(dp_display, 0);
 
        rc = dp_display_unprepare(dp);
        if (rc)
                DRM_ERROR("DP display unprepare failed, rc=%d\n", rc);
 
-       dp_del_event(dp_display, EV_DISCONNECT_PENDING_TIMEOUT);
-
-       state =  atomic_read(&dp_display->hpd_state);
+       state =  dp_display->hpd_state;
        if (state == ST_DISCONNECT_PENDING) {
                /* completed disconnection */
-               atomic_set(&dp_display->hpd_state, ST_DISCONNECTED);
+               dp_display->hpd_state = ST_DISCONNECTED;
        } else {
-               atomic_set(&dp_display->hpd_state, ST_SUSPEND_PENDING);
+               dp_display->hpd_state = ST_SUSPEND_PENDING;
        }
 
        mutex_unlock(&dp_display->event_mutex);
diff --git a/drivers/gpu/drm/msm/dp/dp_reg.h b/drivers/gpu/drm/msm/dp/dp_reg.h
index 43042ff90a19..268602803d9a 100644
--- a/drivers/gpu/drm/msm/dp/dp_reg.h
+++ b/drivers/gpu/drm/msm/dp/dp_reg.h
@@ -32,6 +32,8 @@
 #define DP_DP_IRQ_HPD_INT_ACK                  (0x00000002)
 #define DP_DP_HPD_REPLUG_INT_ACK               (0x00000004)
 #define DP_DP_HPD_UNPLUG_INT_ACK               (0x00000008)
+#define DP_DP_HPD_STATE_STATUS_BITS_MASK       (0x0000000F)
+#define DP_DP_HPD_STATE_STATUS_BITS_SHIFT      (0x1C)
 
 #define REG_DP_DP_HPD_INT_MASK                 (0x0000000C)
 #define DP_DP_HPD_PLUG_INT_MASK                        (0x00000001)

base-commit: d1ea914925856d397b0b3241428f20b945e31434
-- 
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