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

[Michael Tretter <m.tretter@pengutronix.de>]

On Wed, 26 Jul 2023 14:15:58 +0200, Sascha Hauer wrote:
> 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?

I don't remember, why I implemented it as it is. Using of_parse_phandle_from()
should work. I will test it and send a v2.

Michael

> 
> 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
> > 
> > 
> >