[PATCH] clk: fixed_rate: Avoid calling dev_read_*() if CONFIG_OF_PLATDATA=y

[Simon Glass]

Hi Marek,

On Thu, 20 Nov 2025 at 21:39, Marek Vasut <marek.vasut at mailbox.org> wrote:
>
> On 11/21/25 12:40 AM, Simon Glass wrote:
> > Hi Marek,
> >
> > On Wed, 19 Nov 2025 at 21:14, Marek Vasut
> > <marek.vasut+renesas at mailbox.org> wrote:
> >>
> >> If CONFIG_OF_PLATDATA=y , then the udevice has no valid OF node associated
> >> with it and ofnode_valid(node) evaluates to 0. The dev_read_u32_default()
> >> call ultimately reaches ofnode_read_u32_index() which invokes fdt_getprop()
> >> and passes result of ofnode_to_offset(node) as an offset parameter into it.
> >>
> >> The ofnode_to_offset(node) returns -1 for invalid node, which leads to an
> >> fdt_getprop(..., -1, ...) invocation, which will crash sandbox with SIGSEGV
> >> because libfdt can not handle negative node offsets without full tree check,
> >> which U-Boot inhibits to keep size lower.
> >>
> >> Add dev_has_ofnode(dev) check and do not assign clock rate in case the
> >> device has no valid node associated with it, and do not call any of the
> >> dev_read_*() functions for devices without valid nodes.
> >>
> >> Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
> >> ---
> >> Cc: Patrice Chotard <patrice.chotard at foss.st.com>
> >> Cc: Patrick Delaunay <patrick.delaunay at foss.st.com>
> >> Cc: Sean Anderson <seanga2 at gmail.com>
> >> Cc: Tom Rini <trini at konsulko.com>
> >> Cc: u-boot at lists.denx.de
> >> ---
> >>   drivers/clk/clk_fixed_rate.c | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/clk/clk_fixed_rate.c b/drivers/clk/clk_fixed_rate.c
> >> index 95a77d2e041..5c32ae207fe 100644
> >> --- a/drivers/clk/clk_fixed_rate.c
> >> +++ b/drivers/clk/clk_fixed_rate.c
> >> @@ -35,7 +35,7 @@ void clk_fixed_rate_ofdata_to_plat_(struct udevice *dev,
> >>                                      struct clk_fixed_rate *plat)
> >>   {
> >>          struct clk *clk = &plat->clk;
> >> -       if (CONFIG_IS_ENABLED(OF_REAL))
> >> +       if (CONFIG_IS_ENABLED(OF_REAL) && dev_has_ofnode(dev))
> >>                  plat->fixed_rate = dev_read_u32_default(dev, "clock-frequency",
> >>                                                          0);
> >
> > What is happening here? It should already be checking this:
> >
> > static inline __attribute_const__ bool dev_has_ofnode(const struct udevice *dev)
> > {
> > #if CONFIG_IS_ENABLED(OF_REAL)
> > return ofnode_valid(dev_ofnode(dev));
> > #else
> > return false;
> > #endif
> > }
> I do not understand the question -- this patch _adds_ the
> dev_has_ofnode() test into clk_fixed_rate_ofdata_to_plat_() , it wasn't
> present before. Can you please rephrase your question / concern ?

The dev_has_ofnode() function already checks OF_REAL, as shown above. To repeat:

> > static inline __attribute_const__ bool dev_has_ofnode(const struct udevice *dev)
> > {
> > #if CONFIG_IS_ENABLED(OF_REAL)
> > return ofnode_valid(dev_ofnode(dev));
> > #else
> > return false;

   ^^ returns false here

> > #endif

You are adding another check in the caller:

> >> -       if (CONFIG_IS_ENABLED(OF_REAL))
> >> +       if (CONFIG_IS_ENABLED(OF_REAL) && dev_has_ofnode(dev))

dev_has_ofnode() will already return false if OF_REAL is not enabled.
So what is the point of checking OF_REAL before calling
dev_has_ofnode() ?

I don't understand what benefit this patch brings.

Regards,
Simon