linux-kernel - Re: [PATCH] drm/ingenic: Fix driver not probing when IPU port is missing

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Message-ID: <20200827043857.GA471795@ravnborg.org>
Date:   Thu, 27 Aug 2020 06:38:57 +0200
From:   Sam Ravnborg <sam@...nborg.org>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        od@...c.me, Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
        MIPS Creator CI20 Development 
        <mips-creator-ci20-dev@...glegroups.com>
Subject: Re: [PATCH] drm/ingenic: Fix driver not probing when IPU port is
 missing

Hi Paul.

On Wed, Aug 26, 2020 at 11:58:41PM +0200, Paul Cercueil wrote:
> Even if support for the IPU was compiled in, we may run on a device
> (e.g. the Qi LB60) where the IPU is not available, or simply with an old
> devicetree without the IPU node. In that case the ingenic-drm refused to
> probe.
> 
> Fix the driver so that it will probe even if the IPU node is not present
> in devicetree (but then IPU support is disabled of course).
> 
> Fixes: fc1acf317b01 ("drm/ingenic: Add support for the IPU")
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
>  drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 23 ++++++++++++++++-------
>  1 file changed, 16 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> index ada990a7f911..216b67f1672e 100644
> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> @@ -673,6 +673,18 @@ static void ingenic_drm_unbind_all(void *d)
>  	component_unbind_all(priv->dev, &priv->drm);
>  }
>  
> +static inline struct device_node *ingenic_drm_get_ipu_node(struct device *dev)
> +{
> +	/* IPU is at port address 8 */
> +	return of_graph_get_remote_node(dev->of_node, 8, 0);
> +}
kernel-doc for of_graph_get_remote_node() says:

    * Return: Remote device node associated with remote endpoint node linked
    *	   to @node. Use of_node_put() on it when done.

In other words this code leaks a device node.
This was the case with the old code too.

	Sam

> +
> +static inline bool ingenic_drm_has_ipu(struct device *dev)
> +{
> +	return IS_ENABLED(CONFIG_DRM_INGENIC_IPU) &&
> +		!!ingenic_drm_get_ipu_node(dev);
> +}
> +
>  static int ingenic_drm_bind(struct device *dev)
>  {
>  	struct platform_device *pdev = to_platform_device(dev);
> @@ -808,7 +820,7 @@ static int ingenic_drm_bind(struct device *dev)
>  			return ret;
>  		}
>  
> -		if (IS_ENABLED(CONFIG_DRM_INGENIC_IPU)) {
> +		if (ingenic_drm_has_ipu(dev)) {
>  			ret = component_bind_all(dev, drm);
>  			if (ret) {
>  				if (ret != -EPROBE_DEFER)
> @@ -970,12 +982,9 @@ static int ingenic_drm_probe(struct platform_device *pdev)
>  	if (!IS_ENABLED(CONFIG_DRM_INGENIC_IPU))
>  		return ingenic_drm_bind(dev);
>  
> -	/* IPU is at port address 8 */
> -	np = of_graph_get_remote_node(dev->of_node, 8, 0);
> -	if (!np) {
> -		dev_err(dev, "Unable to get IPU node\n");
> -		return -EINVAL;
> -	}
> +	np = ingenic_drm_get_ipu_node(dev);
> +	if (!np)
> +		return ingenic_drm_bind(dev);
>  
>  	drm_of_component_match_add(dev, &match, compare_of, np);
>  
> -- 
> 2.28.0