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