diff mbox series

[v9,1/4] drm/msm/dp: Add eDP support via aux_bus

Message ID 1650618666-15342-2-git-send-email-quic_sbillaka@quicinc.com (mailing list archive)
State Superseded
Headers show
Series Add support for the eDP panel over aux_bus | expand

Commit Message

Sankeerth Billakanti (QUIC) April 22, 2022, 9:11 a.m. UTC
This patch adds support for generic eDP sink through aux_bus. The eDP/DP
controller driver should support aux transactions originating from the
panel-edp driver and hence should be initialized and ready.

The panel bridge supporting the panel should be ready before the bridge
connector is initialized. The generic panel probe needs the controller
resources to be enabled to support the aux transactions originating from
the panel probe.

Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
---
Changes in v9:
  - add comments for panel probe
  - modify the error handling checks

Changes in v8:
  - handle corner cases
  - add comment for the bridge ops

Changes in v7:
  - aux_bus is mandatory for eDP
  - connector type check modified to just check for eDP

Changes in v6:
  - Remove initialization
  - Fix aux_bus node leak
  - Split the patches

 drivers/gpu/drm/msm/dp/dp_display.c | 73 +++++++++++++++++++++++++++++++++++--
 drivers/gpu/drm/msm/dp/dp_display.h |  1 +
 drivers/gpu/drm/msm/dp/dp_drm.c     | 21 +++++++++--
 drivers/gpu/drm/msm/dp/dp_parser.c  | 23 +-----------
 drivers/gpu/drm/msm/dp/dp_parser.h  | 13 ++++++-
 5 files changed, 101 insertions(+), 30 deletions(-)

Comments

Doug Anderson April 22, 2022, 2:03 p.m. UTC | #1
Hi,

On Fri, Apr 22, 2022 at 2:11 AM Sankeerth Billakanti
<quic_sbillaka@quicinc.com> wrote:
>
> This patch adds support for generic eDP sink through aux_bus. The eDP/DP
> controller driver should support aux transactions originating from the
> panel-edp driver and hence should be initialized and ready.
>
> The panel bridge supporting the panel should be ready before the bridge
> connector is initialized. The generic panel probe needs the controller
> resources to be enabled to support the aux transactions originating from
> the panel probe.
>
> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
> ---
> Changes in v9:
>   - add comments for panel probe
>   - modify the error handling checks
>
> Changes in v8:
>   - handle corner cases
>   - add comment for the bridge ops
>
> Changes in v7:
>   - aux_bus is mandatory for eDP
>   - connector type check modified to just check for eDP
>
> Changes in v6:
>   - Remove initialization
>   - Fix aux_bus node leak
>   - Split the patches
>
>  drivers/gpu/drm/msm/dp/dp_display.c | 73 +++++++++++++++++++++++++++++++++++--
>  drivers/gpu/drm/msm/dp/dp_display.h |  1 +
>  drivers/gpu/drm/msm/dp/dp_drm.c     | 21 +++++++++--
>  drivers/gpu/drm/msm/dp/dp_parser.c  | 23 +-----------
>  drivers/gpu/drm/msm/dp/dp_parser.h  | 13 ++++++-
>  5 files changed, 101 insertions(+), 30 deletions(-)

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Stephen Boyd April 23, 2022, 12:13 a.m. UTC | #2
Quoting Sankeerth Billakanti (2022-04-22 02:11:03)
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index d7a19d6..055681a 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c

Some nitpicks

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

> @@ -1508,7 +1509,8 @@ void msm_dp_irq_postinstall(struct msm_dp *dp_display)
>
>         dp_hpd_event_setup(dp);
>
> -       dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
> +       if (!dp_display->is_edp)
> +               dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);

Did it turn out that in fact DP isn't ready still to setup even after
delaying the irq?

>  }
>
>  void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
> @@ -1530,6 +1532,65 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
>         }
>  }
>
> +static int dp_display_get_next_bridge(struct msm_dp *dp)
> +{
> +       int rc;
> +       struct dp_display_private *dp_priv;
> +       struct device_node *aux_bus;
> +       struct device *dev;
> +
> +       dp_priv = container_of(dp, struct dp_display_private, dp_display);
> +       dev = &dp_priv->pdev->dev;
> +       aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
> +
> +       if (aux_bus && dp->is_edp) {
> +               dp_display_host_init(dp_priv);
> +               dp_catalog_ctrl_hpd_config(dp_priv->catalog);
> +               dp_display_host_phy_init(dp_priv);
> +               enable_irq(dp_priv->irq);
> +
> +               /*
> +                * The code below assumes that the panel will finish probing
> +                * by the time devm_of_dp_aux_populate_ep_devices() returns.
> +                * This isn't a great assumption since it will fail if the
> +                * panel driver is probed asynchronously but is the best we
> +                * can do without a bigger driver reorganization.
> +                */
> +               rc = devm_of_dp_aux_populate_ep_devices(dp_priv->aux);
> +               of_node_put(aux_bus);
> +               if (rc)
> +                       goto error;
> +       } else if (dp->is_edp) {
> +               DRM_ERROR("eDP aux_bus not found\n");
> +               return -ENODEV;
> +       }
> +
> +       /*
> +        * External bridges are mandatory for eDP interfaces: one has to
> +        * provide at least an eDP panel (which gets wrapped into panel-bridge).
> +        *
> +        * For DisplayPort interfaces external bridges are optional, so
> +        * silently ignore an error if one is not present (-ENODEV).
> +        */
> +       rc = dp_parser_find_next_bridge(dp_priv->parser);
> +       if (!dp->is_edp && rc == -ENODEV)
> +               return 0;
> +       else if (rc)

Just an if because there's a return above.

> +               goto error;
> +
> +       dp->next_bridge = dp_priv->parser->next_bridge;

In which case it almost feels like it could be written

	if (!dp->is_edp && rc == -ENODEV)
		return 0;
	if (!rc) {
		dp->next_bridge = dp_priv->parser->next_bridge;
		return 0;
	}
error:
	if (dp->is_edp) {

but I'm not worried either way, besides removing the else from the else-if.

> +
> +       return 0;
> +
> +error:
> +       if (dp->is_edp) {
> +               disable_irq(dp_priv->irq);
> +               dp_display_host_phy_exit(dp_priv);
> +               dp_display_host_deinit(dp_priv);
> +       }
> +       return rc;
> +}
> +
>  int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev,
>                         struct drm_encoder *encoder)
>  {
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
> index d371bae..950416c 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.h
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.h
> @@ -125,7 +125,7 @@ struct dp_parser {
>         u32 max_dp_lanes;
>         struct drm_bridge *next_bridge;
>
> -       int (*parse)(struct dp_parser *parser, int connector_type);
> +       int (*parse)(struct dp_parser *parser);
>  };
>
>  /**
> @@ -141,4 +141,15 @@ struct dp_parser {
>   */
>  struct dp_parser *dp_parser_get(struct platform_device *pdev);
>
> +/**
> + * dp_parser_find_next_bridge() - find an additional bridge to DP
> + *
> + * @parser: dp_parser data from client
> + * return: 0 if able to get the bridge else return an error code

return comes after the description below. Also should be capitalized.
You can check this by compiling with W=1 I believe, or run the
kernel doc format script on the file..

> + *
> + * This function is used to find any additional bridge attached to
> + * the DP controller. The eDP interface requires a panel bridge.

Return: 0 if able to get the bridge, otherwise negative errno for failure

> + */
> +int dp_parser_find_next_bridge(struct dp_parser *parser);
> +
Sankeerth Billakanti (QUIC) April 25, 2022, 9:39 a.m. UTC | #3
Hi Stephen,

>Quoting Sankeerth Billakanti (2022-04-22 02:11:03)
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
>> b/drivers/gpu/drm/msm/dp/dp_display.c
>> index d7a19d6..055681a 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>
>Some nitpicks
>
>Reviewed-by: Stephen Boyd <swboyd@chromium.org>
>
>> @@ -1508,7 +1509,8 @@ void msm_dp_irq_postinstall(struct msm_dp
>> *dp_display)
>>
>>         dp_hpd_event_setup(dp);
>>
>> -       dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
>> +       if (!dp_display->is_edp)
>> +               dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
>
>Did it turn out that in fact DP isn't ready still to setup even after delaying the
>irq?
>

The host_init, config_hpd, phy_init and enable_irq are happening in modeset_init already for eDP.
So, I am not scheduling the EV_HPD_INIT_SETUP event for eDP. I am not modifying the delay for DP.

>>  }
>>
>>  void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor
>> *minor) @@ -1530,6 +1532,65 @@ void msm_dp_debugfs_init(struct
>msm_dp *dp_display, struct drm_minor *minor)
>>         }
>>  }
>>
>> +static int dp_display_get_next_bridge(struct msm_dp *dp) {
>> +       int rc;
>> +       struct dp_display_private *dp_priv;
>> +       struct device_node *aux_bus;
>> +       struct device *dev;
>> +
>> +       dp_priv = container_of(dp, struct dp_display_private, dp_display);
>> +       dev = &dp_priv->pdev->dev;
>> +       aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
>> +
>> +       if (aux_bus && dp->is_edp) {
>> +               dp_display_host_init(dp_priv);
>> +               dp_catalog_ctrl_hpd_config(dp_priv->catalog);
>> +               dp_display_host_phy_init(dp_priv);
>> +               enable_irq(dp_priv->irq);
>> +
>> +               /*
>> +                * The code below assumes that the panel will finish probing
>> +                * by the time devm_of_dp_aux_populate_ep_devices() returns.
>> +                * This isn't a great assumption since it will fail if the
>> +                * panel driver is probed asynchronously but is the best we
>> +                * can do without a bigger driver reorganization.
>> +                */
>> +               rc = devm_of_dp_aux_populate_ep_devices(dp_priv->aux);
>> +               of_node_put(aux_bus);
>> +               if (rc)
>> +                       goto error;
>> +       } else if (dp->is_edp) {
>> +               DRM_ERROR("eDP aux_bus not found\n");
>> +               return -ENODEV;
>> +       }
>> +
>> +       /*
>> +        * External bridges are mandatory for eDP interfaces: one has to
>> +        * provide at least an eDP panel (which gets wrapped into panel-
>bridge).
>> +        *
>> +        * For DisplayPort interfaces external bridges are optional, so
>> +        * silently ignore an error if one is not present (-ENODEV).
>> +        */
>> +       rc = dp_parser_find_next_bridge(dp_priv->parser);
>> +       if (!dp->is_edp && rc == -ENODEV)
>> +               return 0;
>> +       else if (rc)
>
>Just an if because there's a return above.
>

Okay

>> +               goto error;
>> +
>> +       dp->next_bridge = dp_priv->parser->next_bridge;
>
>In which case it almost feels like it could be written
>
>	if (!dp->is_edp && rc == -ENODEV)
>		return 0;
>	if (!rc) {
>		dp->next_bridge = dp_priv->parser->next_bridge;
>		return 0;
>	}
>error:
>	if (dp->is_edp) {
>
>but I'm not worried either way, besides removing the else from the else-if.
>

Okay

>> +
>> +       return 0;
>> +
>> +error:
>> +       if (dp->is_edp) {
>> +               disable_irq(dp_priv->irq);
>> +               dp_display_host_phy_exit(dp_priv);
>> +               dp_display_host_deinit(dp_priv);
>> +       }
>> +       return rc;
>> +}
>> +
>>  int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device
>*dev,
>>                         struct drm_encoder *encoder)  { diff --git
>> a/drivers/gpu/drm/msm/dp/dp_parser.h
>> b/drivers/gpu/drm/msm/dp/dp_parser.h
>> index d371bae..950416c 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_parser.h
>> +++ b/drivers/gpu/drm/msm/dp/dp_parser.h
>> @@ -125,7 +125,7 @@ struct dp_parser {
>>         u32 max_dp_lanes;
>>         struct drm_bridge *next_bridge;
>>
>> -       int (*parse)(struct dp_parser *parser, int connector_type);
>> +       int (*parse)(struct dp_parser *parser);
>>  };
>>
>>  /**
>> @@ -141,4 +141,15 @@ struct dp_parser {
>>   */
>>  struct dp_parser *dp_parser_get(struct platform_device *pdev);
>>
>> +/**
>> + * dp_parser_find_next_bridge() - find an additional bridge to DP
>> + *
>> + * @parser: dp_parser data from client
>> + * return: 0 if able to get the bridge else return an error code
>
>return comes after the description below. Also should be capitalized.
>You can check this by compiling with W=1 I believe, or run the kernel doc
>format script on the file..
>

Okay

>> + *
>> + * This function is used to find any additional bridge attached to
>> + * the DP controller. The eDP interface requires a panel bridge.
>
>Return: 0 if able to get the bridge, otherwise negative errno for failure
>

Okay

>> + */
>> +int dp_parser_find_next_bridge(struct dp_parser *parser);
>> +
Stephen Boyd April 25, 2022, 8:26 p.m. UTC | #4
Quoting Sankeerth Billakanti (QUIC) (2022-04-25 02:39:43)
> Hi Stephen,
>
> >Quoting Sankeerth Billakanti (2022-04-22 02:11:03)
> >> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
> >> b/drivers/gpu/drm/msm/dp/dp_display.c
> >> index d7a19d6..055681a 100644
> >> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> >> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> >
> >Some nitpicks
> >
> >Reviewed-by: Stephen Boyd <swboyd@chromium.org>
> >
> >> @@ -1508,7 +1509,8 @@ void msm_dp_irq_postinstall(struct msm_dp
> >> *dp_display)
> >>
> >>         dp_hpd_event_setup(dp);
> >>
> >> -       dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
> >> +       if (!dp_display->is_edp)
> >> +               dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
> >
> >Did it turn out that in fact DP isn't ready still to setup even after delaying the
> >irq?
> >
>
> The host_init, config_hpd, phy_init and enable_irq are happening in modeset_init already for eDP.
> So, I am not scheduling the EV_HPD_INIT_SETUP event for eDP. I am not modifying the delay for DP.

Cool. That didn't answer my question though. Why does DP still need the
delay? I thought recent changes made it unnecessary.
Dmitry Baryshkov April 25, 2022, 9:12 p.m. UTC | #5
On 25/04/2022 23:26, Stephen Boyd wrote:
> Quoting Sankeerth Billakanti (QUIC) (2022-04-25 02:39:43)
>> Hi Stephen,
>>
>>> Quoting Sankeerth Billakanti (2022-04-22 02:11:03)
>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
>>>> b/drivers/gpu/drm/msm/dp/dp_display.c
>>>> index d7a19d6..055681a 100644
>>>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>>>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>>>
>>> Some nitpicks
>>>
>>> Reviewed-by: Stephen Boyd <swboyd@chromium.org>
>>>
>>>> @@ -1508,7 +1509,8 @@ void msm_dp_irq_postinstall(struct msm_dp
>>>> *dp_display)
>>>>
>>>>          dp_hpd_event_setup(dp);
>>>>
>>>> -       dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
>>>> +       if (!dp_display->is_edp)
>>>> +               dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
>>>
>>> Did it turn out that in fact DP isn't ready still to setup even after delaying the
>>> irq?
>>>
>>
>> The host_init, config_hpd, phy_init and enable_irq are happening in modeset_init already for eDP.
>> So, I am not scheduling the EV_HPD_INIT_SETUP event for eDP. I am not modifying the delay for DP.
> 
> Cool. That didn't answer my question though. Why does DP still need the
> delay? I thought recent changes made it unnecessary.

I'd say that if it is not necessary, it should be changed in the 
separate commit. The question is valid nevertheless.
Sankeerth Billakanti (QUIC) April 26, 2022, 1:58 a.m. UTC | #6
Hi Stephen,

>>>> Quoting Sankeerth Billakanti (2022-04-22 02:11:03)
>>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
>>>>> b/drivers/gpu/drm/msm/dp/dp_display.c
>>>>> index d7a19d6..055681a 100644
>>>>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>>>>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>>>>
>>>> Some nitpicks
>>>>
>>>> Reviewed-by: Stephen Boyd <swboyd@chromium.org>
>>>>
>>>>> @@ -1508,7 +1509,8 @@ void msm_dp_irq_postinstall(struct msm_dp
>>>>> *dp_display)
>>>>>
>>>>>          dp_hpd_event_setup(dp);
>>>>>
>>>>> -       dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
>>>>> +       if (!dp_display->is_edp)
>>>>> +               dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
>>>>
>>>> Did it turn out that in fact DP isn't ready still to setup even
>>>> after delaying the irq?
>>>>
>>>
>>> The host_init, config_hpd, phy_init and enable_irq are happening in
>modeset_init already for eDP.
>>> So, I am not scheduling the EV_HPD_INIT_SETUP event for eDP. I am not
>modifying the delay for DP.
>>
>> Cool. That didn't answer my question though. Why does DP still need
>> the delay? I thought recent changes made it unnecessary.
>
>I'd say that if it is not necessary, it should be changed in the separate commit.
>The question is valid nevertheless.
>

Yes, that is right. The delay is unnecessary with the recent changes.
Like Dmitry rightly suggested, we will remove the delay in a separate commit.

>
>--
>With best wishes
>Dmitry
diff mbox series

Patch

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index d7a19d6..055681a 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -10,6 +10,7 @@ 
 #include <linux/component.h>
 #include <linux/of_irq.h>
 #include <linux/delay.h>
+#include <drm/dp/drm_dp_aux_bus.h>
 
 #include "msm_drv.h"
 #include "msm_kms.h"
@@ -259,14 +260,12 @@  static int dp_display_bind(struct device *dev, struct device *master,
 	dp->dp_display.drm_dev = drm;
 	priv->dp[dp->id] = &dp->dp_display;
 
-	rc = dp->parser->parse(dp->parser, dp->dp_display.connector_type);
+	rc = dp->parser->parse(dp->parser);
 	if (rc) {
 		DRM_ERROR("device tree parsing failed\n");
 		goto end;
 	}
 
-	dp->dp_display.next_bridge = dp->parser->next_bridge;
-
 	dp->aux->drm_dev = drm;
 	rc = dp_aux_register(dp->aux);
 	if (rc) {
@@ -1319,6 +1318,8 @@  static int dp_display_probe(struct platform_device *pdev)
 	dp->pdev = pdev;
 	dp->name = "drm_dp";
 	dp->dp_display.connector_type = desc->connector_type;
+	dp->dp_display.is_edp =
+		(dp->dp_display.connector_type == DRM_MODE_CONNECTOR_eDP);
 
 	rc = dp_init_sub_modules(dp);
 	if (rc) {
@@ -1508,7 +1509,8 @@  void msm_dp_irq_postinstall(struct msm_dp *dp_display)
 
 	dp_hpd_event_setup(dp);
 
-	dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
+	if (!dp_display->is_edp)
+		dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
 }
 
 void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
@@ -1530,6 +1532,65 @@  void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
 	}
 }
 
+static int dp_display_get_next_bridge(struct msm_dp *dp)
+{
+	int rc;
+	struct dp_display_private *dp_priv;
+	struct device_node *aux_bus;
+	struct device *dev;
+
+	dp_priv = container_of(dp, struct dp_display_private, dp_display);
+	dev = &dp_priv->pdev->dev;
+	aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
+
+	if (aux_bus && dp->is_edp) {
+		dp_display_host_init(dp_priv);
+		dp_catalog_ctrl_hpd_config(dp_priv->catalog);
+		dp_display_host_phy_init(dp_priv);
+		enable_irq(dp_priv->irq);
+
+		/*
+		 * The code below assumes that the panel will finish probing
+		 * by the time devm_of_dp_aux_populate_ep_devices() returns.
+		 * This isn't a great assumption since it will fail if the
+		 * panel driver is probed asynchronously but is the best we
+		 * can do without a bigger driver reorganization.
+		 */
+		rc = devm_of_dp_aux_populate_ep_devices(dp_priv->aux);
+		of_node_put(aux_bus);
+		if (rc)
+			goto error;
+	} else if (dp->is_edp) {
+		DRM_ERROR("eDP aux_bus not found\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * External bridges are mandatory for eDP interfaces: one has to
+	 * provide at least an eDP panel (which gets wrapped into panel-bridge).
+	 *
+	 * For DisplayPort interfaces external bridges are optional, so
+	 * silently ignore an error if one is not present (-ENODEV).
+	 */
+	rc = dp_parser_find_next_bridge(dp_priv->parser);
+	if (!dp->is_edp && rc == -ENODEV)
+		return 0;
+	else if (rc)
+		goto error;
+
+	dp->next_bridge = dp_priv->parser->next_bridge;
+
+	return 0;
+
+error:
+	if (dp->is_edp) {
+		disable_irq(dp_priv->irq);
+		dp_display_host_phy_exit(dp_priv);
+		dp_display_host_deinit(dp_priv);
+	}
+	return rc;
+}
+
 int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev,
 			struct drm_encoder *encoder)
 {
@@ -1553,6 +1614,10 @@  int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev,
 
 	dp_display->encoder = encoder;
 
+	ret = dp_display_get_next_bridge(dp_display);
+	if (ret)
+		return ret;
+
 	dp_display->bridge = dp_bridge_init(dp_display, dev, encoder);
 	if (IS_ERR(dp_display->bridge)) {
 		ret = PTR_ERR(dp_display->bridge);
diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
index 49a1d89..1377cc3 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.h
+++ b/drivers/gpu/drm/msm/dp/dp_display.h
@@ -21,6 +21,7 @@  struct msm_dp {
 	bool audio_enabled;
 	bool power_on;
 	unsigned int connector_type;
+	bool is_edp;
 
 	hdmi_codec_plugged_cb plugged_cb;
 
diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
index 7ce1aca..8a75c55 100644
--- a/drivers/gpu/drm/msm/dp/dp_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_drm.c
@@ -114,10 +114,23 @@  struct drm_bridge *dp_bridge_init(struct msm_dp *dp_display, struct drm_device *
 	bridge->funcs = &dp_bridge_ops;
 	bridge->type = dp_display->connector_type;
 
-	bridge->ops =
-		DRM_BRIDGE_OP_DETECT |
-		DRM_BRIDGE_OP_HPD |
-		DRM_BRIDGE_OP_MODES;
+	/*
+	 * Many ops only make sense for DP. Why?
+	 * - Detect/HPD are used by DRM to know if a display is _physically_
+	 *   there, not whether the display is powered on / finished initting.
+	 *   On eDP we assume the display is always there because you can't
+	 *   know until power is applied. If we don't implement the ops DRM will
+	 *   assume our display is always there.
+	 * - Currently eDP mode reading is driven by the panel driver. This
+	 *   allows the panel driver to properly power itself on to read the
+	 *   modes.
+	 */
+	if (!dp_display->is_edp) {
+		bridge->ops =
+			DRM_BRIDGE_OP_DETECT |
+			DRM_BRIDGE_OP_HPD |
+			DRM_BRIDGE_OP_MODES;
+	}
 
 	rc = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 	if (rc) {
diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
index 1056b8d..4bdbf91 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.c
+++ b/drivers/gpu/drm/msm/dp/dp_parser.c
@@ -265,7 +265,7 @@  static int dp_parser_clock(struct dp_parser *parser)
 	return 0;
 }
 
-static int dp_parser_find_next_bridge(struct dp_parser *parser)
+int dp_parser_find_next_bridge(struct dp_parser *parser)
 {
 	struct device *dev = &parser->pdev->dev;
 	struct drm_bridge *bridge;
@@ -279,7 +279,7 @@  static int dp_parser_find_next_bridge(struct dp_parser *parser)
 	return 0;
 }
 
-static int dp_parser_parse(struct dp_parser *parser, int connector_type)
+static int dp_parser_parse(struct dp_parser *parser)
 {
 	int rc = 0;
 
@@ -300,25 +300,6 @@  static int dp_parser_parse(struct dp_parser *parser, int connector_type)
 	if (rc)
 		return rc;
 
-	/*
-	 * External bridges are mandatory for eDP interfaces: one has to
-	 * provide at least an eDP panel (which gets wrapped into panel-bridge).
-	 *
-	 * For DisplayPort interfaces external bridges are optional, so
-	 * silently ignore an error if one is not present (-ENODEV).
-	 */
-	rc = dp_parser_find_next_bridge(parser);
-	if (rc == -ENODEV) {
-		if (connector_type == DRM_MODE_CONNECTOR_eDP) {
-			DRM_ERROR("eDP: next bridge is not present\n");
-			return rc;
-		}
-	} else if (rc) {
-		if (rc != -EPROBE_DEFER)
-			DRM_ERROR("DP: error parsing next bridge: %d\n", rc);
-		return rc;
-	}
-
 	/* Map the corresponding regulator information according to
 	 * version. Currently, since we only have one supported platform,
 	 * mapping the regulator directly.
diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
index d371bae..950416c 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.h
+++ b/drivers/gpu/drm/msm/dp/dp_parser.h
@@ -125,7 +125,7 @@  struct dp_parser {
 	u32 max_dp_lanes;
 	struct drm_bridge *next_bridge;
 
-	int (*parse)(struct dp_parser *parser, int connector_type);
+	int (*parse)(struct dp_parser *parser);
 };
 
 /**
@@ -141,4 +141,15 @@  struct dp_parser {
  */
 struct dp_parser *dp_parser_get(struct platform_device *pdev);
 
+/**
+ * dp_parser_find_next_bridge() - find an additional bridge to DP
+ *
+ * @parser: dp_parser data from client
+ * return: 0 if able to get the bridge else return an error code
+ *
+ * This function is used to find any additional bridge attached to
+ * the DP controller. The eDP interface requires a panel bridge.
+ */
+int dp_parser_find_next_bridge(struct dp_parser *parser);
+
 #endif