[PATCH v7 2/2] drm/msm/dp: do not initialize phy until plugin interrupt received

[PATCH v7 2/2] drm/msm/dp: do not initialize phy until plugin interrupt received

[Kuogee Hsieh]

Current DP drivers have regulators, clocks, irq and phy are grouped
together within a function and executed not in a symmetric manner.
This increase difficulty of code maintenance and limited code scalability.
This patch divides the driver life cycle of operation into four states,
resume (including booting up), dongle plugin, dongle unplugged and suspend.
Regulators, core clocks and irq are grouped together and enabled at resume
(or booting up) so that the DP controller is armed and ready to receive HPD
plugin interrupts. HPD plugin interrupt is generated when a dongle plugs
into DUT (device under test). Once HPD plugin interrupt is received, DP
controller will initialize phy so that dpcd read/write will function and
following link training can be proceeded successfully. DP phy will be
disabled after main link is teared down at end of unplugged HPD interrupt
handle triggered by dongle unplugged out of DUT. Finally regulators, code
clocks and irq are disabled at corresponding suspension.

Changes in V2:
-- removed unnecessary dp_ctrl NULL check
-- removed unnecessary phy init_count and power_count DRM_DEBUG_DP logs
-- remove flip parameter out of dp_ctrl_irq_enable()
-- add fixes tag

Changes in V3:
-- call dp_display_host_phy_init() instead of dp_ctrl_phy_init() at
        dp_display_host_init() for eDP

Changes in V4:
-- rewording commit text to match this commit changes

Changes in V5:
-- rebase on top of msm-next branch

Changes in V6:
-- delete flip variable

Changes in V7:
-- dp_ctrl_irq_enable/disabe() merged into dp_ctrl_reset_irq_ctrl()

Fixes: 8ede2ecc3e5e ("drm/msm/dp: Add DP compliance tests on Snapdragon Chipsets")
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c    | 77 ++++++++++++----------------------
 drivers/gpu/drm/msm/dp/dp_ctrl.h    |  8 ++--
 drivers/gpu/drm/msm/dp/dp_display.c | 84 ++++++++++++++++++++++++++-----------
 3 files changed, 92 insertions(+), 77 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index c724cb0..39558a2 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1365,60 +1365,44 @@ static int dp_ctrl_enable_stream_clocks(struct dp_ctrl_private *ctrl)
 	return ret;
 }
 
-int dp_ctrl_host_init(struct dp_ctrl *dp_ctrl, bool flip, bool reset)
+void dp_ctrl_reset_irq_ctrl(struct dp_ctrl *dp_ctrl, bool enable)
+{
+	struct dp_ctrl_private *ctrl;
+
+	ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl);
+
+	dp_catalog_ctrl_reset(ctrl->catalog);
+
+	if (enable)
+		dp_catalog_ctrl_enable_irq(ctrl->catalog, enable);
+}
+
+void dp_ctrl_phy_init(struct dp_ctrl *dp_ctrl)
 {
 	struct dp_ctrl_private *ctrl;
 	struct dp_io *dp_io;
 	struct phy *phy;
 
-	if (!dp_ctrl) {
-		DRM_ERROR("Invalid input data\n");
-		return -EINVAL;
-	}
-
 	ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl);
 	dp_io = &ctrl->parser->io;
 	phy = dp_io->phy;
 
-	ctrl->dp_ctrl.orientation = flip;
-
-	if (reset)
-		dp_catalog_ctrl_reset(ctrl->catalog);
-
-	DRM_DEBUG_DP("flip=%d\n", flip);
 	dp_catalog_ctrl_phy_reset(ctrl->catalog);
 	phy_init(phy);
-	dp_catalog_ctrl_enable_irq(ctrl->catalog, true);
-
-	return 0;
 }
 
-/**
- * dp_ctrl_host_deinit() - Uninitialize DP controller
- * @dp_ctrl: Display Port Driver data
- *
- * Perform required steps to uninitialize DP controller
- * and its resources.
- */
-void dp_ctrl_host_deinit(struct dp_ctrl *dp_ctrl)
+void dp_ctrl_phy_exit(struct dp_ctrl *dp_ctrl)
 {
 	struct dp_ctrl_private *ctrl;
 	struct dp_io *dp_io;
 	struct phy *phy;
 
-	if (!dp_ctrl) {
-		DRM_ERROR("Invalid input data\n");
-		return;
-	}
-
 	ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl);
 	dp_io = &ctrl->parser->io;
 	phy = dp_io->phy;
 
-	dp_catalog_ctrl_enable_irq(ctrl->catalog, false);
+	dp_catalog_ctrl_phy_reset(ctrl->catalog);
 	phy_exit(phy);
-
-	DRM_DEBUG_DP("Host deinitialized successfully\n");
 }
 
 static bool dp_ctrl_use_fixed_nvid(struct dp_ctrl_private *ctrl)
@@ -1893,8 +1877,14 @@ int dp_ctrl_off_link_stream(struct dp_ctrl *dp_ctrl)
 		return ret;
 	}
 
+	DRM_DEBUG_DP("Before, phy=%x init_count=%d power_on=%d\n",
+		(u32)(uintptr_t)phy, phy->init_count, phy->power_count);
+
 	phy_power_off(phy);
 
+	DRM_DEBUG_DP("After, phy=%x init_count=%d power_on=%d\n",
+		(u32)(uintptr_t)phy, phy->init_count, phy->power_count);
+
 	/* aux channel down, reinit phy */
 	phy_exit(phy);
 	phy_init(phy);
@@ -1903,23 +1893,6 @@ int dp_ctrl_off_link_stream(struct dp_ctrl *dp_ctrl)
 	return ret;
 }
 
-void dp_ctrl_off_phy(struct dp_ctrl *dp_ctrl)
-{
-	struct dp_ctrl_private *ctrl;
-	struct dp_io *dp_io;
-	struct phy *phy;
-
-	ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl);
-	dp_io = &ctrl->parser->io;
-	phy = dp_io->phy;
-
-	dp_catalog_ctrl_reset(ctrl->catalog);
-
-	phy_exit(phy);
-
-	DRM_DEBUG_DP("DP off phy done\n");
-}
-
 int dp_ctrl_off(struct dp_ctrl *dp_ctrl)
 {
 	struct dp_ctrl_private *ctrl;
@@ -1947,10 +1920,14 @@ int dp_ctrl_off(struct dp_ctrl *dp_ctrl)
 		DRM_ERROR("Failed to disable link clocks. ret=%d\n", ret);
 	}
 
+	DRM_DEBUG_DP("Before, phy=%x init_count=%d power_on=%d\n",
+		(u32)(uintptr_t)phy, phy->init_count, phy->power_count);
+
 	phy_power_off(phy);
-	phy_exit(phy);
 
-	DRM_DEBUG_DP("DP off done\n");
+	DRM_DEBUG_DP("After, phy=%x init_count=%d power_on=%d\n",
+		(u32)(uintptr_t)phy, phy->init_count, phy->power_count);
+
 	return ret;
 }
 
diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.h b/drivers/gpu/drm/msm/dp/dp_ctrl.h
index 2363a2d..2433edb 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.h
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.h
@@ -19,12 +19,9 @@ struct dp_ctrl {
 	u32 pixel_rate;
 };
 
-int dp_ctrl_host_init(struct dp_ctrl *dp_ctrl, bool flip, bool reset);
-void dp_ctrl_host_deinit(struct dp_ctrl *dp_ctrl);
 int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl);
 int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl);
 int dp_ctrl_off_link_stream(struct dp_ctrl *dp_ctrl);
-void dp_ctrl_off_phy(struct dp_ctrl *dp_ctrl);
 int dp_ctrl_off(struct dp_ctrl *dp_ctrl);
 void dp_ctrl_push_idle(struct dp_ctrl *dp_ctrl);
 void dp_ctrl_isr(struct dp_ctrl *dp_ctrl);
@@ -34,4 +31,9 @@ struct dp_ctrl *dp_ctrl_get(struct device *dev, struct dp_link *link,
 			struct dp_power *power, struct dp_catalog *catalog,
 			struct dp_parser *parser);
 
+void dp_ctrl_reset_irq_ctrl(struct dp_ctrl *dp_ctrl, bool enable);
+void dp_ctrl_phy_init(struct dp_ctrl *dp_ctrl);
+void dp_ctrl_phy_exit(struct dp_ctrl *dp_ctrl);
+void dp_ctrl_irq_phy_exit(struct dp_ctrl *dp_ctrl);
+
 #endif /* _DP_CTRL_H_ */
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 0766752..cfbc5e4 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -83,6 +83,7 @@ struct dp_display_private {
 
 	/* state variables */
 	bool core_initialized;
+	bool phy_initialized;
 	bool hpd_irq_on;
 	bool audio_supported;
 
@@ -371,21 +372,46 @@ static int dp_display_process_hpd_high(struct dp_display_private *dp)
 	return rc;
 }
 
-static void dp_display_host_init(struct dp_display_private *dp, int reset)
+static void dp_display_host_phy_init(struct dp_display_private *dp)
 {
-	bool flip = false;
+	DRM_DEBUG_DP("core_init=%d phy_init=%d\n",
+			dp->core_initialized, dp->phy_initialized);
 
+	if (!dp->phy_initialized) {
+		dp_ctrl_phy_init(dp->ctrl);
+		dp->phy_initialized = true;
+	}
+}
+
+static void dp_display_host_phy_exit(struct dp_display_private *dp)
+{
+	DRM_DEBUG_DP("core_init=%d phy_init=%d\n",
+			dp->core_initialized, dp->phy_initialized);
+
+	if (dp->phy_initialized) {
+		dp_ctrl_phy_exit(dp->ctrl);
+		dp->phy_initialized = false;
+	}
+}
+
+static void dp_display_host_init(struct dp_display_private *dp)
+{
 	DRM_DEBUG_DP("core_initialized=%d\n", dp->core_initialized);
 	if (dp->core_initialized) {
 		DRM_DEBUG_DP("DP core already initialized\n");
 		return;
 	}
 
-	if (dp->usbpd->orientation == ORIENTATION_CC2)
-		flip = true;
+	dp_power_init(dp->power, false);
+	dp_ctrl_reset_irq_ctrl(dp->ctrl, true);
+
+	/*
+	 * eDP is the embedded primary display and has its own phy
+	 * initialize phy immediately
+	 */
+	if (dp->dp_display.connector_type == DRM_MODE_CONNECTOR_eDP)
+		dp_display_host_phy_init(dp);
 
-	dp_power_init(dp->power, flip);
-	dp_ctrl_host_init(dp->ctrl, flip, reset);
 	dp_aux_init(dp->aux);
 	dp->core_initialized = true;
 }
@@ -397,7 +423,7 @@ static void dp_display_host_deinit(struct dp_display_private *dp)
 		return;
 	}
 
-	dp_ctrl_host_deinit(dp->ctrl);
+	dp_ctrl_reset_irq_ctrl(dp->ctrl, false);
 	dp_aux_deinit(dp->aux);
 	dp_power_deinit(dp->power);
 
@@ -408,7 +434,7 @@ static int dp_display_usbpd_configure_cb(struct device *dev)
 {
 	struct dp_display_private *dp = dev_get_dp_display_private(dev);
 
-	dp_display_host_init(dp, false);
+	dp_display_host_phy_init(dp);
 
 	return dp_display_process_hpd_high(dp);
 }
@@ -532,7 +558,7 @@ static int dp_hpd_plug_handle(struct dp_display_private *dp, u32 data)
 		dp->hpd_state = ST_DISCONNECTED;
 
 		if (ret == -ECONNRESET) { /* cable unplugged */
-			dp->core_initialized = false;
+			dp->phy_initialized = false;
 		}
 
 	} else {
@@ -604,8 +630,7 @@ static int dp_hpd_unplug_handle(struct dp_display_private *dp, u32 data)
 	if (state == ST_DISCONNECTED) {
 		/* triggered by irq_hdp with sink_count = 0 */
 		if (dp->link->sink_count == 0) {
-			dp_ctrl_off_phy(dp->ctrl);
-			dp->core_initialized = false;
+			dp_display_host_phy_exit(dp);
 		}
 		mutex_unlock(&dp->event_mutex);
 		return 0;
@@ -698,9 +723,8 @@ static int dp_irq_hpd_handle(struct dp_display_private *dp, u32 data)
 	 */
 	if (dp->core_initialized) {
 		ret = dp_display_usbpd_attention_cb(&dp->pdev->dev);
-		if (ret == -ECONNRESET) { /* cable unplugged */
-			dp->core_initialized = false;
-		}
+		if (ret == -ECONNRESET)	/* cable unplugged */
+			dp->phy_initialized = false;
 	}
 	DRM_DEBUG_DP("hpd_state=%d\n", state);
 
@@ -892,12 +916,19 @@ static int dp_display_disable(struct dp_display_private *dp, u32 data)
 
 	dp_display->audio_enabled = false;
 
-	/* triggered by irq_hpd with sink_count = 0 */
 	if (dp->link->sink_count == 0) {
+		/*
+		 * irq_hpd with sink_count = 0
+		 * hdmi unplugged out of dongle
+		 */
 		dp_ctrl_off_link_stream(dp->ctrl);
 	} else {
+		/*
+		 * unplugged interrupt
+		 * dongle unplugged out of DUT
+		 */
 		dp_ctrl_off(dp->ctrl);
-		dp->core_initialized = false;
+		dp_display_host_phy_exit(dp);
 	}
 
 	dp_display->power_on = false;
@@ -1027,7 +1058,7 @@ void msm_dp_snapshot(struct msm_disp_state *disp_state, struct msm_dp *dp)
 static void dp_display_config_hpd(struct dp_display_private *dp)
 {
 
-	dp_display_host_init(dp, true);
+	dp_display_host_init(dp);
 	dp_catalog_ctrl_hpd_config(dp->catalog);
 
 	/* Enable interrupt first time
@@ -1306,20 +1337,23 @@ static int dp_pm_resume(struct device *dev)
 	dp->hpd_state = ST_DISCONNECTED;
 
 	/* turn on dp ctrl/phy */
-	dp_display_host_init(dp, true);
+	dp_display_host_init(dp);
 
 	dp_catalog_ctrl_hpd_config(dp->catalog);
 
-	/*
-	 * set sink to normal operation mode -- D0
-	 * before dpcd read
-	 */
-	dp_link_psm_config(dp->link, &dp->panel->link_info, false);
 
 	if (dp_catalog_link_is_connected(dp->catalog)) {
+		/*
+		 * set sink to normal operation mode -- D0
+		 * before dpcd read
+		 */
+		dp_display_host_phy_init(dp);
+		dp_link_psm_config(dp->link, &dp->panel->link_info, false);
 		sink_count = drm_dp_read_sink_count(dp->aux);
 		if (sink_count < 0)
 			sink_count = 0;
+
+		dp_display_host_phy_exit(dp);
 	}
 
 	dp->link->sink_count = sink_count;
@@ -1366,6 +1400,8 @@ static int dp_pm_suspend(struct device *dev)
 		dp_display_host_deinit(dp);
 	}
 
+	dp_display_host_phy_exit(dp);
+
 	dp->hpd_state = ST_SUSPENDED;
 
 	/* host_init will be called at pm_resume */
@@ -1523,7 +1559,7 @@ int msm_dp_display_enable(struct msm_dp *dp, struct drm_encoder *encoder)
 	state =  dp_display->hpd_state;
 
 	if (state == ST_DISPLAY_OFF)
-		dp_display_host_init(dp_display, true);
+		dp_display_host_phy_init(dp_display);
 
 	dp_display_enable(dp_display, 0);
 
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v7 2/2] drm/msm/dp: do not initialize phy until plugin interrupt received

[Stephen Boyd]

Quoting Kuogee Hsieh (2021-12-09 13:35:07)
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 0766752..cfbc5e4 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -83,6 +83,7 @@ struct dp_display_private {
>
>         /* state variables */
>         bool core_initialized;
> +       bool phy_initialized;
>         bool hpd_irq_on;
>         bool audio_supported;
>
> @@ -371,21 +372,46 @@ static int dp_display_process_hpd_high(struct dp_display_private *dp)
>         return rc;
>  }
>
> -static void dp_display_host_init(struct dp_display_private *dp, int reset)
> +static void dp_display_host_phy_init(struct dp_display_private *dp)
>  {
> -       bool flip = false;
> +       DRM_DEBUG_DP("core_init=%d phy_init=%d\n",
> +                       dp->core_initialized, dp->phy_initialized);
>
> +       if (!dp->phy_initialized) {

Is this check only here because we don't know when this function is
getting called? I see in the DP case we get here from
dp_display_usbpd_configure_cb() but in the eDP case we get here from
dp_display_host_init() and presumably again from
dp_display_usbpd_configure_cb() called by dp_hpd_plug_handle().

If at all possible, I'd prefer to not have another tracking variable and
call dp_display_host_phy_init() from the same place regardless of DP or
eDP. Doing that would make it symmetric, per the commit text.

> +               dp_ctrl_phy_init(dp->ctrl);
> +               dp->phy_initialized = true;
> +       }
> +}
> +
> +static void dp_display_host_phy_exit(struct dp_display_private *dp)
> +{
> +       DRM_DEBUG_DP("core_init=%d phy_init=%d\n",
> +                       dp->core_initialized, dp->phy_initialized);
> +
> +       if (dp->phy_initialized) {
> +               dp_ctrl_phy_exit(dp->ctrl);
> +               dp->phy_initialized = false;
> +       }
> +}
> +
> +static void dp_display_host_init(struct dp_display_private *dp)
> +{
>         DRM_DEBUG_DP("core_initialized=%d\n", dp->core_initialized);
>         if (dp->core_initialized) {
>                 DRM_DEBUG_DP("DP core already initialized\n");
>                 return;
>         }
>
> -       if (dp->usbpd->orientation == ORIENTATION_CC2)
> -               flip = true;
> +       dp_power_init(dp->power, false);
> +       dp_ctrl_reset_irq_ctrl(dp->ctrl, true);
> +
> +       /*
> +        * eDP is the embedded primary display and has its own phy
> +        * initialize phy immediately

Can we get some more details here? Why is it better to initialize the
phy here vs. when HPD goes high on the panel? The comment says what the
code is doing but it isn't telling us why that's OK.

> +        */
> +       if (dp->dp_display.connector_type == DRM_MODE_CONNECTOR_eDP)
> +               dp_display_host_phy_init(dp);
>
> -       dp_power_init(dp->power, flip);
> -       dp_ctrl_host_init(dp->ctrl, flip, reset);
>         dp_aux_init(dp->aux);
>         dp->core_initialized = true;
>  }

Re: [PATCH v7 2/2] drm/msm/dp: do not initialize phy until plugin interrupt received

[Kuogee Hsieh]

On 12/14/2021 5:50 PM, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2021-12-09 13:35:07)
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
>> index 0766752..cfbc5e4 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>> @@ -83,6 +83,7 @@ struct dp_display_private {
>>
>>          /* state variables */
>>          bool core_initialized;
>> +       bool phy_initialized;
>>          bool hpd_irq_on;
>>          bool audio_supported;
>>
>> @@ -371,21 +372,46 @@ static int dp_display_process_hpd_high(struct dp_display_private *dp)
>>          return rc;
>>   }
>>
>> -static void dp_display_host_init(struct dp_display_private *dp, int reset)
>> +static void dp_display_host_phy_init(struct dp_display_private *dp)
>>   {
>> -       bool flip = false;
>> +       DRM_DEBUG_DP("core_init=%d phy_init=%d\n",
>> +                       dp->core_initialized, dp->phy_initialized);
>>
>> +       if (!dp->phy_initialized) {
> Is this check only here because we don't know when this function is
> getting called? I see in the DP case we get here from
> dp_display_usbpd_configure_cb() but in the eDP case we get here from
> dp_display_host_init() and presumably again from
> dp_display_usbpd_configure_cb() called by dp_hpd_plug_handle().
>
> If at all possible, I'd prefer to not have another tracking variable and
> call dp_display_host_phy_init() from the same place regardless of DP or
> eDP. Doing that would make it symmetric, per the commit text.

Agree, but  dp->phy_initialized variable used to track some other 
conditions.

For example, phy required to be re inited if dpcd read failed due to 
cable unplugged.

other dpcd read failed will not required to re inited.

Therefore I think dp->phy_initialized variable is still required.

>> +               dp_ctrl_phy_init(dp->ctrl);
>> +               dp->phy_initialized = true;
>> +       }
>> +}
>> +
>> +static void dp_display_host_phy_exit(struct dp_display_private *dp)
>> +{
>> +       DRM_DEBUG_DP("core_init=%d phy_init=%d\n",
>> +                       dp->core_initialized, dp->phy_initialized);
>> +
>> +       if (dp->phy_initialized) {
>> +               dp_ctrl_phy_exit(dp->ctrl);
>> +               dp->phy_initialized = false;
>> +       }
>> +}
>> +
>> +static void dp_display_host_init(struct dp_display_private *dp)
>> +{
>>          DRM_DEBUG_DP("core_initialized=%d\n", dp->core_initialized);
>>          if (dp->core_initialized) {
>>                  DRM_DEBUG_DP("DP core already initialized\n");
>>                  return;
>>          }
>>
>> -       if (dp->usbpd->orientation == ORIENTATION_CC2)
>> -               flip = true;
>> +       dp_power_init(dp->power, false);
>> +       dp_ctrl_reset_irq_ctrl(dp->ctrl, true);
>> +
>> +       /*
>> +        * eDP is the embedded primary display and has its own phy
>> +        * initialize phy immediately
> Can we get some more details here? Why is it better to initialize the
> phy here vs. when HPD goes high on the panel? The comment says what the
> code is doing but it isn't telling us why that's OK.

Will do.

>
>> +        */
>> +       if (dp->dp_display.connector_type == DRM_MODE_CONNECTOR_eDP)
>> +               dp_display_host_phy_init(dp);
>>
>> -       dp_power_init(dp->power, flip);
>> -       dp_ctrl_host_init(dp->ctrl, flip, reset);
>>          dp_aux_init(dp->aux);
>>          dp->core_initialized = true;
>>   }