[PATCH] drm/bridge: Move devm_drm_of_get_bridge to bridge/panel.c

[PATCH] drm/bridge: Move devm_drm_of_get_bridge to bridge/panel.c

[Maxime Ripard]

By depending on devm_drm_panel_bridge_add(), devm_drm_of_get_bridge()
introduces a circular dependency between the modules drm (where
devm_drm_of_get_bridge() ends up) and drm_kms_helper (where
devm_drm_panel_bridge_add() is).

Fix this by moving devm_drm_of_get_bridge() to bridge/panel.c and thus
drm_kms_helper.

Fixes: 87ea95808d53 ("drm/bridge: Add a function to abstract away panels")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

---

Hi Stephen,

I think it fixes the issue, but couldn't reproduce it here with my
config for some reason.

Let me know if it works for you.

Maxime
---
 drivers/gpu/drm/bridge/panel.c | 36 ++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_bridge.c   | 34 --------------------------------
 2 files changed, 36 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
index c916f4b8907e..285a079cdef5 100644
--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -332,3 +332,39 @@ struct drm_connector *drm_panel_bridge_connector(struct drm_bridge *bridge)
 	return &panel_bridge->connector;
 }
 EXPORT_SYMBOL(drm_panel_bridge_connector);
+
+#ifdef CONFIG_OF
+/**
+ * devm_drm_of_get_bridge - Return next bridge in the chain
+ * @dev: device to tie the bridge lifetime to
+ * @np: device tree node containing encoder output ports
+ * @port: port in the device tree node
+ * @endpoint: endpoint in the device tree node
+ *
+ * Given a DT node's port and endpoint number, finds the connected node
+ * and returns the associated bridge if any, or creates and returns a
+ * drm panel bridge instance if a panel is connected.
+ *
+ * Returns a pointer to the bridge if successful, or an error pointer
+ * otherwise.
+ */
+struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
+					  struct device_node *np,
+					  u32 port, u32 endpoint)
+{
+	struct drm_bridge *bridge;
+	struct drm_panel *panel;
+	int ret;
+
+	ret = drm_of_find_panel_or_bridge(np, port, endpoint,
+					  &panel, &bridge);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (panel)
+		bridge = devm_drm_panel_bridge_add(dev, panel);
+
+	return bridge;
+}
+EXPORT_SYMBOL(devm_drm_of_get_bridge);
+#endif
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 4c68733fa660..7ee29f073857 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -1232,40 +1232,6 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 	return NULL;
 }
 EXPORT_SYMBOL(of_drm_find_bridge);
-
-/**
- * devm_drm_of_get_bridge - Return next bridge in the chain
- * @dev: device to tie the bridge lifetime to
- * @np: device tree node containing encoder output ports
- * @port: port in the device tree node
- * @endpoint: endpoint in the device tree node
- *
- * Given a DT node's port and endpoint number, finds the connected node
- * and returns the associated bridge if any, or creates and returns a
- * drm panel bridge instance if a panel is connected.
- *
- * Returns a pointer to the bridge if successful, or an error pointer
- * otherwise.
- */
-struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
-					  struct device_node *np,
-					  u32 port, u32 endpoint)
-{
-	struct drm_bridge *bridge;
-	struct drm_panel *panel;
-	int ret;
-
-	ret = drm_of_find_panel_or_bridge(np, port, endpoint,
-					  &panel, &bridge);
-	if (ret)
-		return ERR_PTR(ret);
-
-	if (panel)
-		bridge = devm_drm_panel_bridge_add(dev, panel);
-
-	return bridge;
-}
-EXPORT_SYMBOL(devm_drm_of_get_bridge);
 #endif
 
 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
-- 
2.31.1

Re: [PATCH] drm/bridge: Move devm_drm_of_get_bridge to bridge/panel.c

[Thomas Zimmermann]

[-- Attachment #1.1: Type: text/plain, Size: 4301 bytes --]



Am 17.09.21 um 20:09 schrieb Maxime Ripard:
> By depending on devm_drm_panel_bridge_add(), devm_drm_of_get_bridge()
> introduces a circular dependency between the modules drm (where
> devm_drm_of_get_bridge() ends up) and drm_kms_helper (where
> devm_drm_panel_bridge_add() is).
> 
> Fix this by moving devm_drm_of_get_bridge() to bridge/panel.c and thus
> drm_kms_helper.
> 
> Fixes: 87ea95808d53 ("drm/bridge: Add a function to abstract away panels")
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>

> 
> ---
> 
> Hi Stephen,
> 
> I think it fixes the issue, but couldn't reproduce it here with my
> config for some reason.
> 
> Let me know if it works for you.
> 
> Maxime
> ---
>   drivers/gpu/drm/bridge/panel.c | 36 ++++++++++++++++++++++++++++++++++
>   drivers/gpu/drm/drm_bridge.c   | 34 --------------------------------
>   2 files changed, 36 insertions(+), 34 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
> index c916f4b8907e..285a079cdef5 100644
> --- a/drivers/gpu/drm/bridge/panel.c
> +++ b/drivers/gpu/drm/bridge/panel.c
> @@ -332,3 +332,39 @@ struct drm_connector *drm_panel_bridge_connector(struct drm_bridge *bridge)
>   	return &panel_bridge->connector;
>   }
>   EXPORT_SYMBOL(drm_panel_bridge_connector);
> +
> +#ifdef CONFIG_OF
> +/**
> + * devm_drm_of_get_bridge - Return next bridge in the chain
> + * @dev: device to tie the bridge lifetime to
> + * @np: device tree node containing encoder output ports
> + * @port: port in the device tree node
> + * @endpoint: endpoint in the device tree node
> + *
> + * Given a DT node's port and endpoint number, finds the connected node
> + * and returns the associated bridge if any, or creates and returns a
> + * drm panel bridge instance if a panel is connected.
> + *
> + * Returns a pointer to the bridge if successful, or an error pointer
> + * otherwise.
> + */
> +struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
> +					  struct device_node *np,
> +					  u32 port, u32 endpoint)
> +{
> +	struct drm_bridge *bridge;
> +	struct drm_panel *panel;
> +	int ret;
> +
> +	ret = drm_of_find_panel_or_bridge(np, port, endpoint,
> +					  &panel, &bridge);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	if (panel)
> +		bridge = devm_drm_panel_bridge_add(dev, panel);
> +
> +	return bridge;
> +}
> +EXPORT_SYMBOL(devm_drm_of_get_bridge);
> +#endif
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index 4c68733fa660..7ee29f073857 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -1232,40 +1232,6 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
>   	return NULL;
>   }
>   EXPORT_SYMBOL(of_drm_find_bridge);
> -
> -/**
> - * devm_drm_of_get_bridge - Return next bridge in the chain
> - * @dev: device to tie the bridge lifetime to
> - * @np: device tree node containing encoder output ports
> - * @port: port in the device tree node
> - * @endpoint: endpoint in the device tree node
> - *
> - * Given a DT node's port and endpoint number, finds the connected node
> - * and returns the associated bridge if any, or creates and returns a
> - * drm panel bridge instance if a panel is connected.
> - *
> - * Returns a pointer to the bridge if successful, or an error pointer
> - * otherwise.
> - */
> -struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
> -					  struct device_node *np,
> -					  u32 port, u32 endpoint)
> -{
> -	struct drm_bridge *bridge;
> -	struct drm_panel *panel;
> -	int ret;
> -
> -	ret = drm_of_find_panel_or_bridge(np, port, endpoint,
> -					  &panel, &bridge);
> -	if (ret)
> -		return ERR_PTR(ret);
> -
> -	if (panel)
> -		bridge = devm_drm_panel_bridge_add(dev, panel);
> -
> -	return bridge;
> -}
> -EXPORT_SYMBOL(devm_drm_of_get_bridge);
>   #endif
>   
>   MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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Re: [PATCH] drm/bridge: Move devm_drm_of_get_bridge to bridge/panel.c

[Heiko Stübner]

Hi Maxime,

Am Freitag, 17. September 2021, 20:09:25 CEST schrieb Maxime Ripard:
> By depending on devm_drm_panel_bridge_add(), devm_drm_of_get_bridge()
> introduces a circular dependency between the modules drm (where
> devm_drm_of_get_bridge() ends up) and drm_kms_helper (where
> devm_drm_panel_bridge_add() is).
> 
> Fix this by moving devm_drm_of_get_bridge() to bridge/panel.c and thus
> drm_kms_helper.
> 
> Fixes: 87ea95808d53 ("drm/bridge: Add a function to abstract away panels")
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>

I started with drm-misc-next at
- e46ad85acd90 ("MAINTAINERS: add Andrey as the DRM GPU scheduler maintainer")

with your patch on top, I end up with:

make[1]: Verzeichnis „/home/devel/hstuebner/02_drm/linux/_build-arm64“ wird betreten
  GEN     Makefile
  CALL    ../scripts/atomic/check-atomics.sh
  CALL    ../scripts/checksyscalls.sh
  CC [M]  drivers/gpu/drm/bridge/panel.o
  CC [M]  drivers/gpu/drm/drm_bridge.o
  LD [M]  drivers/gpu/drm/drm.o
../drivers/gpu/drm/bridge/panel.c: In function ‘devm_drm_of_get_bridge’:
../drivers/gpu/drm/bridge/panel.c:359:8: error: implicit declaration of function ‘drm_of_find_panel_or_bridge’ [-Werror=implicit-function-declaration]
  359 |  ret = drm_of_find_panel_or_bridge(np, port, endpoint,
      |        ^~~~~~~~~~~~~~~~~~~~~~~~~~~

adding the following makes it compile again:
diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
index 285a079cdef5..b32295abd9e7 100644
--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -9,6 +9,7 @@
 #include <drm/drm_connector.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>


I obviously also ran into the circular dependency-issue right now,
so with the above addition:

Tested-by: Heiko Stuebner <heiko@sntech.de>


Heiko

> ---
>  drivers/gpu/drm/bridge/panel.c | 36 ++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_bridge.c   | 34 --------------------------------
>  2 files changed, 36 insertions(+), 34 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
> index c916f4b8907e..285a079cdef5 100644
> --- a/drivers/gpu/drm/bridge/panel.c
> +++ b/drivers/gpu/drm/bridge/panel.c
> @@ -332,3 +332,39 @@ struct drm_connector *drm_panel_bridge_connector(struct drm_bridge *bridge)
>  	return &panel_bridge->connector;
>  }
>  EXPORT_SYMBOL(drm_panel_bridge_connector);
> +
> +#ifdef CONFIG_OF
> +/**
> + * devm_drm_of_get_bridge - Return next bridge in the chain
> + * @dev: device to tie the bridge lifetime to
> + * @np: device tree node containing encoder output ports
> + * @port: port in the device tree node
> + * @endpoint: endpoint in the device tree node
> + *
> + * Given a DT node's port and endpoint number, finds the connected node
> + * and returns the associated bridge if any, or creates and returns a
> + * drm panel bridge instance if a panel is connected.
> + *
> + * Returns a pointer to the bridge if successful, or an error pointer
> + * otherwise.
> + */
> +struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
> +					  struct device_node *np,
> +					  u32 port, u32 endpoint)
> +{
> +	struct drm_bridge *bridge;
> +	struct drm_panel *panel;
> +	int ret;
> +
> +	ret = drm_of_find_panel_or_bridge(np, port, endpoint,
> +					  &panel, &bridge);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	if (panel)
> +		bridge = devm_drm_panel_bridge_add(dev, panel);
> +
> +	return bridge;
> +}
> +EXPORT_SYMBOL(devm_drm_of_get_bridge);
> +#endif
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index 4c68733fa660..7ee29f073857 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -1232,40 +1232,6 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
>  	return NULL;
>  }
>  EXPORT_SYMBOL(of_drm_find_bridge);
> -
> -/**
> - * devm_drm_of_get_bridge - Return next bridge in the chain
> - * @dev: device to tie the bridge lifetime to
> - * @np: device tree node containing encoder output ports
> - * @port: port in the device tree node
> - * @endpoint: endpoint in the device tree node
> - *
> - * Given a DT node's port and endpoint number, finds the connected node
> - * and returns the associated bridge if any, or creates and returns a
> - * drm panel bridge instance if a panel is connected.
> - *
> - * Returns a pointer to the bridge if successful, or an error pointer
> - * otherwise.
> - */
> -struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
> -					  struct device_node *np,
> -					  u32 port, u32 endpoint)
> -{
> -	struct drm_bridge *bridge;
> -	struct drm_panel *panel;
> -	int ret;
> -
> -	ret = drm_of_find_panel_or_bridge(np, port, endpoint,
> -					  &panel, &bridge);
> -	if (ret)
> -		return ERR_PTR(ret);
> -
> -	if (panel)
> -		bridge = devm_drm_panel_bridge_add(dev, panel);
> -
> -	return bridge;
> -}
> -EXPORT_SYMBOL(devm_drm_of_get_bridge);
>  #endif
>  
>  MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
> 

Re: [PATCH] drm/bridge: Move devm_drm_of_get_bridge to bridge/panel.c

[Maxime Ripard]

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On Mon, Sep 20, 2021 at 10:49:55PM +0200, Heiko Stübner wrote:
> Hi Maxime,
> 
> Am Freitag, 17. September 2021, 20:09:25 CEST schrieb Maxime Ripard:
> > By depending on devm_drm_panel_bridge_add(), devm_drm_of_get_bridge()
> > introduces a circular dependency between the modules drm (where
> > devm_drm_of_get_bridge() ends up) and drm_kms_helper (where
> > devm_drm_panel_bridge_add() is).
> > 
> > Fix this by moving devm_drm_of_get_bridge() to bridge/panel.c and thus
> > drm_kms_helper.
> > 
> > Fixes: 87ea95808d53 ("drm/bridge: Add a function to abstract away panels")
> > Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> 
> I started with drm-misc-next at
> - e46ad85acd90 ("MAINTAINERS: add Andrey as the DRM GPU scheduler maintainer")
> 
> with your patch on top, I end up with:
> 
> make[1]: Verzeichnis „/home/devel/hstuebner/02_drm/linux/_build-arm64“ wird betreten
>   GEN     Makefile
>   CALL    ../scripts/atomic/check-atomics.sh
>   CALL    ../scripts/checksyscalls.sh
>   CC [M]  drivers/gpu/drm/bridge/panel.o
>   CC [M]  drivers/gpu/drm/drm_bridge.o
>   LD [M]  drivers/gpu/drm/drm.o
> ../drivers/gpu/drm/bridge/panel.c: In function ‘devm_drm_of_get_bridge’:
> ../drivers/gpu/drm/bridge/panel.c:359:8: error: implicit declaration of function ‘drm_of_find_panel_or_bridge’ [-Werror=implicit-function-declaration]
>   359 |  ret = drm_of_find_panel_or_bridge(np, port, endpoint,
>       |        ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> adding the following makes it compile again:
> diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
> index 285a079cdef5..b32295abd9e7 100644
> --- a/drivers/gpu/drm/bridge/panel.c
> +++ b/drivers/gpu/drm/bridge/panel.c
> @@ -9,6 +9,7 @@
>  #include <drm/drm_connector.h>
>  #include <drm/drm_encoder.h>
>  #include <drm/drm_modeset_helper_vtables.h>
> +#include <drm/drm_of.h>
>  #include <drm/drm_panel.h>
>  #include <drm/drm_print.h>
>  #include <drm/drm_probe_helper.h>
> 
> 
> I obviously also ran into the circular dependency-issue right now,
> so with the above addition:
> 
> Tested-by: Heiko Stuebner <heiko@sntech.de>

I'm not sure how I missed that, thanks for testing :)

I've just pushed the patch with your fix to drm-misc-fixes

Maxime

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