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

[Shawn Lin <shawn.lin@rock-chips.com>]

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@163.com>
> ---
>   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?

> @@ -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;
>   }
>