Re: [PATCH v8 5/5] PCI: of: Remove max-link-speed generation validation

[Hans Zhang]

On 2026/3/13 15:04, Shawn Lin wrote:
> Hi Hans
>
> 在 2026/03/13 星期五 0:36, Hans Zhang 写道:
> > The of_pci_get_max_link_speed() function currently validates the
> > "max-link-speed" DT property to be in the range 1..4 (Gen1..Gen4).
> > This imposes a maintenance burden because each new PCIe generation
> > would require updating this validation.
> >
> > Remove the range check so the function returns the raw property value
> > (or a negative error code if the property is missing or malformed).
> > Callers must now validate the returned speed against the range they
> > support. A subsequent patch adds such validation to the DWC driver,
> > which is the primary user of this function.
> >
> > Removing the validation from this common function allows future PCIe
> > generations to be supported without modifying drivers/pci/of.c.
> >
> > Signed-off-by: Hans Zhang <18255117159@xxxxxxx>
> > ---
> >   drivers/pci/of.c | 12 +++++++-----
> >   1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> > index 9f8eb5df279e..fbb779a94202 100644
> > --- a/drivers/pci/of.c
> > +++ b/drivers/pci/of.c
> > @@ -875,8 +875,9 @@ EXPORT_SYMBOL_GPL(of_pci_supply_present);
> >    * of_pci_get_max_link_speed - Find the maximum link speed of the 
> > given device node.
> >    * @node: Device tree node with the maximum link speed information.
> >    *
> > - * This function will try to find the limitation of link speed by 
> > finding
> > - * a property called "max-link-speed" of the given device node.
> > + * This function will try to read the "max-link-speed" property of 
> > the given
> > + * device tree node. It does NOT validate the value of the property 
> > (e.g.,
> > + * range checks for PCIe generations).
> >    *
> >    * Return:
> >    * * > 0    - On success, a maximum link speed.
>
> Thanks for the patch. However, after applying it, I noticed this part
> still seems off. There is a detailed comment in the file saying this
> function checks if the max-link-speed is invalid, just a few lines below
> your change. Could you please take another look at that comment and
> adjust them?

Hi Shawn,

Thanks. Will change.

Best regards,
Hans


> > @@ -889,10 +890,11 @@ EXPORT_SYMBOL_GPL(of_pci_supply_present);
> >   int of_pci_get_max_link_speed(struct device_node *node)
> >   {
> >       u32 max_link_speed;
> > +    int ret;
> > -    if (of_property_read_u32(node, "max-link-speed", &max_link_speed) ||
> > -        max_link_speed == 0 || max_link_speed > 4)
> > -        return -EINVAL;
> > +    ret = of_property_read_u32(node, "max-link-speed", &max_link_speed);
> > +    if (ret)
> > +        return ret;
> >       return max_link_speed;
> >   }