Re: [PATCH v7 1/2] PCI: of: Remove max-link-speed generation validation

[Hans Zhang]

On 2026/3/9 08:38, Shawn Lin wrote:
> 在 2026/03/08 星期日 22:26, 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.
> >
> > This change allows future PCIe generations to be supported without
> > modifying drivers/pci/of.c.
> >
> > Signed-off-by: Hans Zhang <18255117159@xxxxxxx>
> > Acked-by: Manivannan Sadhasivam <mani@xxxxxxxxxx>
> > ---
> >   drivers/pci/of.c | 7 ++++---
> >   1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> > index 9f8eb5df279e..cff5fd337c2b 100644
> > --- a/drivers/pci/of.c
> > +++ b/drivers/pci/of.c
> > @@ -889,10 +889,11 @@ EXPORT_SYMBOL_GPL(of_pci_supply_present);
> >   int of_pci_get_max_link_speed(struct device_node *node)
> >   {
> >       u32 max_link_speed;
> > +    int ret;
>
> Should update the comment of this function, as it states:
> "-EINVAL    - Invalid "max-link-speed" property value...
> a negative value if the * required property is not found or is invalid."
>
> So it won't validate the speed after this patch. Perhaps it's even
> better to note the caller to take the responsiblity to validate it.

Hi Shawn,

I plan to modify it as follows. If there are any mistakes, please point 
them out. Thank you very much.

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.
@@ -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;
 }


Best regards,
Hans

> > -    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;
> >   }