Re: [PATCH] of_firmware: fix lookup of fpga manager

[Sascha Hauer <sha@pengutronix.de>]

On Tue, Jul 11, 2023 at 12:19:07PM +0200, Michael Tretter wrote:
> The of_parse_phandle() looks for the phandle in the root device tree,
> but as np is resolved for the target device tree, the phandle refers to
> the target device tree and may return a wrong node in the root tree.
> 
> Therefore, we must ensure that we look for the manager-node in the
> target device tree and look for the manager with that name.
> 
> firmwaremgr_find_by_node already uses the name for the lookup.
> 
> Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
> ---
>  drivers/of/of_firmware.c | 30 ++++++++++++++++++++++++------
>  1 file changed, 24 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/of/of_firmware.c b/drivers/of/of_firmware.c
> index 80feb3b90dba..0429875a26c4 100644
> --- a/drivers/of/of_firmware.c
> +++ b/drivers/of/of_firmware.c
> @@ -9,14 +9,32 @@
>  static struct firmware_mgr *of_node_get_mgr(struct device_node *np)
>  {
>  	struct device_node *mgr_node;
> +	const __be32 *property;
> +	phandle phandle;
> +	int size;
>  
> +	/* Find fpga-mgr phandle, which may be set in a parent fpga-region. */
>  	do {
> -		mgr_node = of_parse_phandle(np, "fpga-mgr", 0);
> -		if (mgr_node)
> -			return firmwaremgr_find_by_node(mgr_node);
> -	} while ((np = of_get_parent(np)) != NULL);

Not sure if I get this completely. Can't you just replace
of_parse_phandle() with of_parse_phandle_from() with the correct
root_node and be done with it?

Sascha

> -
> -	return NULL;
> +		property = of_get_property(np, "fpga-mgr", &size);
> +		if (property && size == sizeof(*property))
> +			break;
> +	} while ((np = of_get_parent(np)) != NULL &&
> +		 of_device_is_compatible(np, "fpga-region"));
> +	if (!property)
> +		return NULL;
> +	phandle = be32_to_cpup(property);
> +
> +	/*
> +	 * The phandle in the np will refer to a device node in the target
> +	 * tree, which may differ from the phandle in the root tree. We need
> +	 * the name of the target node, as firmwaremgr_find_by_node performs
> +	 * the lookup by the node name.
> +	 */
> +	mgr_node = of_find_node_by_phandle_from(phandle, of_find_root_node(np));
> +	if (!mgr_node)
> +		return NULL;
> +
> +	return firmwaremgr_find_by_node(mgr_node);
>  }
>  
>  struct fw_load_entry {
> -- 
> 2.39.2
> 
> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |