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

Hans Zhang
2026-03-13T16:56:46Z

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@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?

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;
>>   }
>>