[PATCH v3 1/3] drm/bridge: introduce bridge detaching mechanism

[PATCH v3 1/3] drm/bridge: introduce bridge detaching mechanism

[Andrea Merello]

Up to now, once a bridge has been attached to a DRM device, it cannot
be undone.

In particular you couldn't rmmod/insmod a DRM driver that uses a bridge,
because the bridge would remain bound to the first (dead) driver instance.

This patch fixes this by introducing drm_encoder_detach() and a ->detach
callback in drm_bridge_funcs for the bridge to be notified about detaches.

It's DRM/KMS driver responsibility to call drm_encoder_detach().

While adding the bridge detach callback, with its kerneldoc, I also added
kerneldoc for attach callback.

Few other kerneldocs fixes around there are included.

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Suggested-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Cc: Archit Taneja <architt@codeaurora.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Lucas Stach <l.stach@pengutronix.de>
---
 drivers/gpu/drm/drm_bridge.c | 29 +++++++++++++++++++++++++++--
 include/drm/drm_crtc.h       | 26 +++++++++++++++++++++++++-
 2 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 2555430..4840466 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -98,11 +98,11 @@ EXPORT_SYMBOL(drm_bridge_remove);
  * @dev: DRM device
  * @bridge: bridge control structure
  *
- * called by a kms driver to link one of our encoder/bridge to the given
+ * Called by a kms driver to link one of our encoder/bridge to the given
  * bridge.
  *
  * Note that setting up links between the bridge and our encoder/bridge
- * objects needs to be handled by the kms driver itself
+ * objects needs to be handled by the kms driver itself.
  *
  * RETURNS:
  * Zero on success, error code on failure
@@ -125,6 +125,31 @@ int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
 EXPORT_SYMBOL(drm_bridge_attach);
 
 /**
+ * drm_bridge_detach - deassociate given bridge from its DRM device
+ *
+ * @bridge: bridge control structure
+ *
+ * Called by a kms driver to unlink the given bridge from its DRM device.
+ *
+ * Note that tearing down links between the bridge and our encoder/bridge
+ * objects needs to be handled by the kms driver itself.
+ */
+void drm_bridge_detach(struct drm_bridge *bridge)
+{
+	if (WARN_ON(!bridge))
+		return;
+
+	if (WARN_ON(!bridge->dev))
+		return;
+
+	if (bridge->funcs->detach)
+		bridge->funcs->detach(bridge);
+
+	bridge->dev = NULL;
+}
+EXPORT_SYMBOL(drm_bridge_detach);
+
+/**
  * DOC: bridge callbacks
  *
  * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 3fa0275..bb214a1 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1118,12 +1118,33 @@ struct drm_plane {
 
 /**
  * struct drm_bridge_funcs - drm_bridge control functions
- * @attach: Called during drm_bridge_attach
  */
 struct drm_bridge_funcs {
+	/**
+	 * @attach:
+	 *
+	 * This callback is invoked whenever our bridge is being attached to a
+	 * &drm_encoder.
+	 *
+	 * The attach callback is optional.
+	 *
+	 * RETURNS:
+	 *
+	 * Zero on success, error code on failure.
+	 */
 	int (*attach)(struct drm_bridge *bridge);
 
 	/**
+	 * @detach:
+	 *
+	 * This callback is invoked whenever our bridge is being detached from a
+	 * &drm_encoder.
+	 *
+	 * The detach callback is optional.
+	 */
+	void (*detach)(struct drm_bridge *bridge);
+
+	/**
 	 * @mode_fixup:
 	 *
 	 * This callback is used to validate and adjust a mode. The paramater
@@ -1137,6 +1158,8 @@ struct drm_bridge_funcs {
 	 * this function passes all other callbacks must succeed for this
 	 * configuration.
 	 *
+	 * The mode_fixup callback is optional.
+	 *
 	 * NOTE:
 	 *
 	 * This function is called in the check phase of atomic modesets, which
@@ -2426,6 +2449,7 @@ extern int drm_bridge_add(struct drm_bridge *bridge);
 extern void drm_bridge_remove(struct drm_bridge *bridge);
 extern struct drm_bridge *of_drm_find_bridge(struct device_node *np);
 extern int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge);
+extern void drm_bridge_detach(struct drm_bridge *bridge);
 
 bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
 			const struct drm_display_mode *mode,
-- 
2.7.4

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[PATCH v3 2/3] drm: simple_kms_helper: make connector optional at init time

[Andrea Merello]

drm_simple_display_pipe_init() pretends to attach a connector
to the display pipe.

In case a drm bridge has to be used, then it's the bridge that
takes care of connectors.

This patch makes the connector parameter optional for
drm_simple_display_pipe_init(), so that a drm bridge could
handle connector by itself later.

Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
---
 drivers/gpu/drm/drm_simple_kms_helper.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
index 4476310..3301e4a 100644
--- a/drivers/gpu/drm/drm_simple_kms_helper.c
+++ b/drivers/gpu/drm/drm_simple_kms_helper.c
@@ -146,10 +146,15 @@ static const struct drm_plane_funcs drm_simple_kms_plane_funcs = {
  * @funcs: callbacks for the display pipe (optional)
  * @formats: array of supported formats (DRM_FORMAT\_\*)
  * @format_count: number of elements in @formats
- * @connector: connector to attach and register
+ * @connector: connector to attach and register (optional)
  *
  * Sets up a display pipeline which consist of a really simple
- * plane-crtc-encoder pipe coupled with the provided connector.
+ * plane-crtc-encoder pipe.
+ *
+ * If a connector is supplied, the pipe will be coupled with the provided
+ * connector. You may supply a NULL connector when using drm bridges, that
+ * handle connectors themselves (see drm_simple_display_pipe_attach_bridge()).
+ *
  * Teardown of a simple display pipe is all handled automatically by the drm
  * core through calling drm_mode_config_cleanup(). Drivers afterwards need to
  * release the memory for the structure themselves.
@@ -188,7 +193,7 @@ int drm_simple_display_pipe_init(struct drm_device *dev,
 	encoder->possible_crtcs = 1 << drm_crtc_index(crtc);
 	ret = drm_encoder_init(dev, encoder, &drm_simple_kms_encoder_funcs,
 			       DRM_MODE_ENCODER_NONE, NULL);
-	if (ret)
+	if (ret || !connector)
 		return ret;
 
 	return drm_mode_connector_attach_encoder(connector, encoder);
-- 
2.7.4

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Re: [PATCH v3 2/3] drm: simple_kms_helper: make connector optional at init time

[Archit Taneja]

On 08/25/2016 02:34 PM, Andrea Merello wrote:
> drm_simple_display_pipe_init() pretends to attach a connector
> to the display pipe.
>
> In case a drm bridge has to be used, then it's the bridge that
> takes care of connectors.
>
> This patch makes the connector parameter optional for
> drm_simple_display_pipe_init(), so that a drm bridge could
> handle connector by itself later.
>

Pushed to drm-misc.

Thanks,
Archit

> Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Noralf Trønnes <noralf@tronnes.org>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> ---
>   drivers/gpu/drm/drm_simple_kms_helper.c | 11 ++++++++---
>   1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
> index 4476310..3301e4a 100644
> --- a/drivers/gpu/drm/drm_simple_kms_helper.c
> +++ b/drivers/gpu/drm/drm_simple_kms_helper.c
> @@ -146,10 +146,15 @@ static const struct drm_plane_funcs drm_simple_kms_plane_funcs = {
>    * @funcs: callbacks for the display pipe (optional)
>    * @formats: array of supported formats (DRM_FORMAT\_\*)
>    * @format_count: number of elements in @formats
> - * @connector: connector to attach and register
> + * @connector: connector to attach and register (optional)
>    *
>    * Sets up a display pipeline which consist of a really simple
> - * plane-crtc-encoder pipe coupled with the provided connector.
> + * plane-crtc-encoder pipe.
> + *
> + * If a connector is supplied, the pipe will be coupled with the provided
> + * connector. You may supply a NULL connector when using drm bridges, that
> + * handle connectors themselves (see drm_simple_display_pipe_attach_bridge()).
> + *
>    * Teardown of a simple display pipe is all handled automatically by the drm
>    * core through calling drm_mode_config_cleanup(). Drivers afterwards need to
>    * release the memory for the structure themselves.
> @@ -188,7 +193,7 @@ int drm_simple_display_pipe_init(struct drm_device *dev,
>   	encoder->possible_crtcs = 1 << drm_crtc_index(crtc);
>   	ret = drm_encoder_init(dev, encoder, &drm_simple_kms_encoder_funcs,
>   			       DRM_MODE_ENCODER_NONE, NULL);
> -	if (ret)
> +	if (ret || !connector)
>   		return ret;
>
>   	return drm_mode_connector_attach_encoder(connector, encoder);
>

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[PATCH v3 3/3] drm: simple_kms_helper: add support for bridges

[Andrea Merello]

Introduce drm_simple_display_pipe_attach_bridge() and
drm_simple_display_pipe_detach_bridge() in order to make it possible to use
drm encoders with the simple display pipes managed by simple_kms_helpers

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
---
 drivers/gpu/drm/drm_simple_kms_helper.c | 40 +++++++++++++++++++++++++++++++++
 include/drm/drm_simple_kms_helper.h     |  5 +++++
 2 files changed, 45 insertions(+)

diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
index 3301e4a..8e9858b 100644
--- a/drivers/gpu/drm/drm_simple_kms_helper.c
+++ b/drivers/gpu/drm/drm_simple_kms_helper.c
@@ -140,6 +140,46 @@ static const struct drm_plane_funcs drm_simple_kms_plane_funcs = {
 };
 
 /**
+ * drm_simple_display_pipe_attach_bridge - Attach a bridge to the display pipe
+ * @pipe: simple display pipe object
+ * @bridge: bridge to attach
+ *
+ * Makes it possible to still use the drm_simple_display_pipe helpers when
+ * a DRM bridge has to be used.
+ *
+ * Note that you probably want to initialize the pipe by passing a NULL
+ * connector to drm_simple_display_pipe_init().
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int drm_simple_display_pipe_attach_bridge(struct drm_simple_display_pipe *pipe,
+					struct drm_bridge *bridge)
+{
+	bridge->encoder = &pipe->encoder;
+	pipe->encoder.bridge = bridge;
+	return drm_bridge_attach(pipe->encoder.dev, bridge);
+}
+EXPORT_SYMBOL(drm_simple_display_pipe_attach_bridge);
+
+/**
+ * drm_simple_display_pipe_detach_bridge - Detach the bridge from the display pipe
+ * @pipe: simple display pipe object
+ *
+ * Detaches the drm bridge previously attached with
+ * drm_simple_display_pipe_attach_bridge()
+ */
+void drm_simple_display_pipe_detach_bridge(struct drm_simple_display_pipe *pipe)
+{
+	if (WARN_ON(!pipe->encoder.bridge))
+		return;
+
+	drm_bridge_detach(pipe->encoder.bridge);
+	pipe->encoder.bridge = NULL;
+}
+EXPORT_SYMBOL(drm_simple_display_pipe_detach_bridge);
+
+/**
  * drm_simple_display_pipe_init - Initialize a simple display pipeline
  * @dev: DRM device
  * @pipe: simple display pipe object to initialize
diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h
index 2690397..5245d1f 100644
--- a/include/drm/drm_simple_kms_helper.h
+++ b/include/drm/drm_simple_kms_helper.h
@@ -85,6 +85,11 @@ struct drm_simple_display_pipe {
 	const struct drm_simple_display_pipe_funcs *funcs;
 };
 
+int drm_simple_display_pipe_attach_bridge(struct drm_simple_display_pipe *pipe,
+					struct drm_bridge *bridge);
+
+void drm_simple_display_pipe_detach_bridge(struct drm_simple_display_pipe *pipe);
+
 int drm_simple_display_pipe_init(struct drm_device *dev,
 			struct drm_simple_display_pipe *pipe,
 			const struct drm_simple_display_pipe_funcs *funcs,
-- 
2.7.4

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Re: [PATCH v3 3/3] drm: simple_kms_helper: add support for bridges

[Archit Taneja]

On 08/25/2016 02:34 PM, Andrea Merello wrote:
> Introduce drm_simple_display_pipe_attach_bridge() and
> drm_simple_display_pipe_detach_bridge() in order to make it possible to use
> drm encoders with the simple display pipes managed by simple_kms_helpers
>
> Suggested-by: Daniel Vetter <daniel@ffwll.ch>
> Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>


Pushed to drm-misc.

Thanks,
Archit

> Cc: Noralf Trønnes <noralf@tronnes.org>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: David Airlie <airlied@linux.ie>
> ---
>   drivers/gpu/drm/drm_simple_kms_helper.c | 40 +++++++++++++++++++++++++++++++++
>   include/drm/drm_simple_kms_helper.h     |  5 +++++
>   2 files changed, 45 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
> index 3301e4a..8e9858b 100644
> --- a/drivers/gpu/drm/drm_simple_kms_helper.c
> +++ b/drivers/gpu/drm/drm_simple_kms_helper.c
> @@ -140,6 +140,46 @@ static const struct drm_plane_funcs drm_simple_kms_plane_funcs = {
>   };
>
>   /**
> + * drm_simple_display_pipe_attach_bridge - Attach a bridge to the display pipe
> + * @pipe: simple display pipe object
> + * @bridge: bridge to attach
> + *
> + * Makes it possible to still use the drm_simple_display_pipe helpers when
> + * a DRM bridge has to be used.
> + *
> + * Note that you probably want to initialize the pipe by passing a NULL
> + * connector to drm_simple_display_pipe_init().
> + *
> + * Returns:
> + * Zero on success, negative error code on failure.
> + */
> +int drm_simple_display_pipe_attach_bridge(struct drm_simple_display_pipe *pipe,
> +					struct drm_bridge *bridge)
> +{
> +	bridge->encoder = &pipe->encoder;
> +	pipe->encoder.bridge = bridge;
> +	return drm_bridge_attach(pipe->encoder.dev, bridge);
> +}
> +EXPORT_SYMBOL(drm_simple_display_pipe_attach_bridge);
> +
> +/**
> + * drm_simple_display_pipe_detach_bridge - Detach the bridge from the display pipe
> + * @pipe: simple display pipe object
> + *
> + * Detaches the drm bridge previously attached with
> + * drm_simple_display_pipe_attach_bridge()
> + */
> +void drm_simple_display_pipe_detach_bridge(struct drm_simple_display_pipe *pipe)
> +{
> +	if (WARN_ON(!pipe->encoder.bridge))
> +		return;
> +
> +	drm_bridge_detach(pipe->encoder.bridge);
> +	pipe->encoder.bridge = NULL;
> +}
> +EXPORT_SYMBOL(drm_simple_display_pipe_detach_bridge);
> +
> +/**
>    * drm_simple_display_pipe_init - Initialize a simple display pipeline
>    * @dev: DRM device
>    * @pipe: simple display pipe object to initialize
> diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h
> index 2690397..5245d1f 100644
> --- a/include/drm/drm_simple_kms_helper.h
> +++ b/include/drm/drm_simple_kms_helper.h
> @@ -85,6 +85,11 @@ struct drm_simple_display_pipe {
>   	const struct drm_simple_display_pipe_funcs *funcs;
>   };
>
> +int drm_simple_display_pipe_attach_bridge(struct drm_simple_display_pipe *pipe,
> +					struct drm_bridge *bridge);
> +
> +void drm_simple_display_pipe_detach_bridge(struct drm_simple_display_pipe *pipe);
> +
>   int drm_simple_display_pipe_init(struct drm_device *dev,
>   			struct drm_simple_display_pipe *pipe,
>   			const struct drm_simple_display_pipe_funcs *funcs,
>

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Re: [PATCH v3 1/3] drm/bridge: introduce bridge detaching mechanism

[Daniel Vetter]

On Thu, Aug 25, 2016 at 11:04:32AM +0200, Andrea Merello wrote:
> Up to now, once a bridge has been attached to a DRM device, it cannot
> be undone.
> 
> In particular you couldn't rmmod/insmod a DRM driver that uses a bridge,
> because the bridge would remain bound to the first (dead) driver instance.
> 
> This patch fixes this by introducing drm_encoder_detach() and a ->detach
> callback in drm_bridge_funcs for the bridge to be notified about detaches.
> 
> It's DRM/KMS driver responsibility to call drm_encoder_detach().
> 
> While adding the bridge detach callback, with its kerneldoc, I also added
> kerneldoc for attach callback.
> 
> Few other kerneldocs fixes around there are included.
> 
> Suggested-by: Daniel Vetter <daniel@ffwll.ch>
> Suggested-by: Lucas Stach <l.stach@pengutronix.de>
> Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
> Cc: Archit Taneja <architt@codeaurora.org>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Lucas Stach <l.stach@pengutronix.de>

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

As discussed on the last round, I'll let Archit apply all 3 to drm-misc,
so he can check them out too.
-Daniel
> ---
>  drivers/gpu/drm/drm_bridge.c | 29 +++++++++++++++++++++++++++--
>  include/drm/drm_crtc.h       | 26 +++++++++++++++++++++++++-
>  2 files changed, 52 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index 2555430..4840466 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -98,11 +98,11 @@ EXPORT_SYMBOL(drm_bridge_remove);
>   * @dev: DRM device
>   * @bridge: bridge control structure
>   *
> - * called by a kms driver to link one of our encoder/bridge to the given
> + * Called by a kms driver to link one of our encoder/bridge to the given
>   * bridge.
>   *
>   * Note that setting up links between the bridge and our encoder/bridge
> - * objects needs to be handled by the kms driver itself
> + * objects needs to be handled by the kms driver itself.
>   *
>   * RETURNS:
>   * Zero on success, error code on failure
> @@ -125,6 +125,31 @@ int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
>  EXPORT_SYMBOL(drm_bridge_attach);
>  
>  /**
> + * drm_bridge_detach - deassociate given bridge from its DRM device
> + *
> + * @bridge: bridge control structure
> + *
> + * Called by a kms driver to unlink the given bridge from its DRM device.
> + *
> + * Note that tearing down links between the bridge and our encoder/bridge
> + * objects needs to be handled by the kms driver itself.
> + */
> +void drm_bridge_detach(struct drm_bridge *bridge)
> +{
> +	if (WARN_ON(!bridge))
> +		return;
> +
> +	if (WARN_ON(!bridge->dev))
> +		return;
> +
> +	if (bridge->funcs->detach)
> +		bridge->funcs->detach(bridge);
> +
> +	bridge->dev = NULL;
> +}
> +EXPORT_SYMBOL(drm_bridge_detach);
> +
> +/**
>   * DOC: bridge callbacks
>   *
>   * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 3fa0275..bb214a1 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -1118,12 +1118,33 @@ struct drm_plane {
>  
>  /**
>   * struct drm_bridge_funcs - drm_bridge control functions
> - * @attach: Called during drm_bridge_attach
>   */
>  struct drm_bridge_funcs {
> +	/**
> +	 * @attach:
> +	 *
> +	 * This callback is invoked whenever our bridge is being attached to a
> +	 * &drm_encoder.
> +	 *
> +	 * The attach callback is optional.
> +	 *
> +	 * RETURNS:
> +	 *
> +	 * Zero on success, error code on failure.
> +	 */
>  	int (*attach)(struct drm_bridge *bridge);
>  
>  	/**
> +	 * @detach:
> +	 *
> +	 * This callback is invoked whenever our bridge is being detached from a
> +	 * &drm_encoder.
> +	 *
> +	 * The detach callback is optional.
> +	 */
> +	void (*detach)(struct drm_bridge *bridge);
> +
> +	/**
>  	 * @mode_fixup:
>  	 *
>  	 * This callback is used to validate and adjust a mode. The paramater
> @@ -1137,6 +1158,8 @@ struct drm_bridge_funcs {
>  	 * this function passes all other callbacks must succeed for this
>  	 * configuration.
>  	 *
> +	 * The mode_fixup callback is optional.
> +	 *
>  	 * NOTE:
>  	 *
>  	 * This function is called in the check phase of atomic modesets, which
> @@ -2426,6 +2449,7 @@ extern int drm_bridge_add(struct drm_bridge *bridge);
>  extern void drm_bridge_remove(struct drm_bridge *bridge);
>  extern struct drm_bridge *of_drm_find_bridge(struct device_node *np);
>  extern int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge);
> +extern void drm_bridge_detach(struct drm_bridge *bridge);
>  
>  bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
>  			const struct drm_display_mode *mode,
> -- 
> 2.7.4
> 

-- 
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Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH v3 1/3] drm/bridge: introduce bridge detaching mechanism

[Archit Taneja]

On 08/25/2016 05:46 PM, Daniel Vetter wrote:
> On Thu, Aug 25, 2016 at 11:04:32AM +0200, Andrea Merello wrote:
>> Up to now, once a bridge has been attached to a DRM device, it cannot
>> be undone.
>>
>> In particular you couldn't rmmod/insmod a DRM driver that uses a bridge,
>> because the bridge would remain bound to the first (dead) driver instance.
>>
>> This patch fixes this by introducing drm_encoder_detach() and a ->detach
>> callback in drm_bridge_funcs for the bridge to be notified about detaches.
>>
>> It's DRM/KMS driver responsibility to call drm_encoder_detach().
>>
>> While adding the bridge detach callback, with its kerneldoc, I also added
>> kerneldoc for attach callback.
>>
>> Few other kerneldocs fixes around there are included.
>>
>> Suggested-by: Daniel Vetter <daniel@ffwll.ch>
>> Suggested-by: Lucas Stach <l.stach@pengutronix.de>
>> Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
>> Cc: Archit Taneja <architt@codeaurora.org>
>> Cc: David Airlie <airlied@linux.ie>
>> Cc: Daniel Vetter <daniel@ffwll.ch>
>> Cc: Lucas Stach <l.stach@pengutronix.de>
>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>
> As discussed on the last round, I'll let Archit apply all 3 to drm-misc,
> so he can check them out too.

Pushed to drm-misc.

Thanks,
Archit

> -Daniel
>> ---
>>   drivers/gpu/drm/drm_bridge.c | 29 +++++++++++++++++++++++++++--
>>   include/drm/drm_crtc.h       | 26 +++++++++++++++++++++++++-
>>   2 files changed, 52 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
>> index 2555430..4840466 100644
>> --- a/drivers/gpu/drm/drm_bridge.c
>> +++ b/drivers/gpu/drm/drm_bridge.c
>> @@ -98,11 +98,11 @@ EXPORT_SYMBOL(drm_bridge_remove);
>>    * @dev: DRM device
>>    * @bridge: bridge control structure
>>    *
>> - * called by a kms driver to link one of our encoder/bridge to the given
>> + * Called by a kms driver to link one of our encoder/bridge to the given
>>    * bridge.
>>    *
>>    * Note that setting up links between the bridge and our encoder/bridge
>> - * objects needs to be handled by the kms driver itself
>> + * objects needs to be handled by the kms driver itself.
>>    *
>>    * RETURNS:
>>    * Zero on success, error code on failure
>> @@ -125,6 +125,31 @@ int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
>>   EXPORT_SYMBOL(drm_bridge_attach);
>>
>>   /**
>> + * drm_bridge_detach - deassociate given bridge from its DRM device
>> + *
>> + * @bridge: bridge control structure
>> + *
>> + * Called by a kms driver to unlink the given bridge from its DRM device.
>> + *
>> + * Note that tearing down links between the bridge and our encoder/bridge
>> + * objects needs to be handled by the kms driver itself.
>> + */
>> +void drm_bridge_detach(struct drm_bridge *bridge)
>> +{
>> +	if (WARN_ON(!bridge))
>> +		return;
>> +
>> +	if (WARN_ON(!bridge->dev))
>> +		return;
>> +
>> +	if (bridge->funcs->detach)
>> +		bridge->funcs->detach(bridge);
>> +
>> +	bridge->dev = NULL;
>> +}
>> +EXPORT_SYMBOL(drm_bridge_detach);
>> +
>> +/**
>>    * DOC: bridge callbacks
>>    *
>>    * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
>> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
>> index 3fa0275..bb214a1 100644
>> --- a/include/drm/drm_crtc.h
>> +++ b/include/drm/drm_crtc.h
>> @@ -1118,12 +1118,33 @@ struct drm_plane {
>>
>>   /**
>>    * struct drm_bridge_funcs - drm_bridge control functions
>> - * @attach: Called during drm_bridge_attach
>>    */
>>   struct drm_bridge_funcs {
>> +	/**
>> +	 * @attach:
>> +	 *
>> +	 * This callback is invoked whenever our bridge is being attached to a
>> +	 * &drm_encoder.
>> +	 *
>> +	 * The attach callback is optional.
>> +	 *
>> +	 * RETURNS:
>> +	 *
>> +	 * Zero on success, error code on failure.
>> +	 */
>>   	int (*attach)(struct drm_bridge *bridge);
>>
>>   	/**
>> +	 * @detach:
>> +	 *
>> +	 * This callback is invoked whenever our bridge is being detached from a
>> +	 * &drm_encoder.
>> +	 *
>> +	 * The detach callback is optional.
>> +	 */
>> +	void (*detach)(struct drm_bridge *bridge);
>> +
>> +	/**
>>   	 * @mode_fixup:
>>   	 *
>>   	 * This callback is used to validate and adjust a mode. The paramater
>> @@ -1137,6 +1158,8 @@ struct drm_bridge_funcs {
>>   	 * this function passes all other callbacks must succeed for this
>>   	 * configuration.
>>   	 *
>> +	 * The mode_fixup callback is optional.
>> +	 *
>>   	 * NOTE:
>>   	 *
>>   	 * This function is called in the check phase of atomic modesets, which
>> @@ -2426,6 +2449,7 @@ extern int drm_bridge_add(struct drm_bridge *bridge);
>>   extern void drm_bridge_remove(struct drm_bridge *bridge);
>>   extern struct drm_bridge *of_drm_find_bridge(struct device_node *np);
>>   extern int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge);
>> +extern void drm_bridge_detach(struct drm_bridge *bridge);
>>
>>   bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
>>   			const struct drm_display_mode *mode,
>> --
>> 2.7.4
>>
>

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
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