linux-kernel - Re: [PATCH] MFD: do not assign already already assigned compatible of

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Date:   Mon, 24 Oct 2016 11:08:05 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Valentin Longchamp <valentin.longchamp@...mile.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MFD: do not assign already already assigned compatible
 of_nodes

On Mon, 19 Sep 2016, Valentin Longchamp wrote:

> If 2 similar cells have the same of_compatible (2 instances of the same
> functionality), they both are assigned the first found of_node with this
> compatible. In the below example, the pdev of both cells get the child@0
> of_node.
> 
> parent@0 { /* MFD devices with 2 cells
> 	reg = <0>;
> 	child@0 {
> 		reg = <0>;
> 		compatible = "child-driver";
> 	};
> 	child@1 {
> 		reg = <1>;
> 		compatible = "child-driver";
> 	};
> };
> 
> To avoid this, the found of_nodes are checked to see if they are already
> assigned in the children of the parent dev and are only assigned if
> still "available" (not assigned to a child).
> 
> This allows the 2nd cell's pdev to get the child@1 of_node.
> 
> Signed-off-by: Valentin Longchamp <valentin.longchamp@...mile.com>
> ---
>  drivers/mfd/mfd-core.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index 3ac486a..11c5ded 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -137,6 +137,19 @@ static inline void mfd_acpi_add_device(const struct mfd_cell *cell,
>  }
>  #endif
>  
> +static inline int is_my_of_node(struct device *dev, void *data)

Rename to mfd_check_node_callback().

> +{
> +	struct device_node *np = data;
> +
> +	return dev->of_node == np;
> +}
> +
> +static inline int of_node_already_in_children(struct device *dev,

Rename to mfd_is_node_allocated_to_dev()

> +					      struct device_node *node)
> +{
> +	return device_for_each_child(dev, node, is_my_of_node);
> +}
> +
>  static int mfd_add_device(struct device *parent, int id,
>  			  const struct mfd_cell *cell, atomic_t *usage_count,
>  			  struct resource *mem_base,
> @@ -178,8 +191,10 @@ static int mfd_add_device(struct device *parent, int id,
>  	if (parent->of_node && cell->of_compatible) {
>  		for_each_child_of_node(parent->of_node, np) {
>  			if (of_device_is_compatible(np, cell->of_compatible)) {
> -				pdev->dev.of_node = np;
> -				break;
> +				if (!of_node_already_in_children(parent, np)) {
> +					pdev->dev.of_node = np;
> +					break;
> +				}
>  			}
>  		}
>  	}

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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