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

[Hans Zhang <18255117159@163.com>]

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@163.com>
>> Acked-by: Manivannan Sadhasivam <mani@kernel.org>
>> ---
>>   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;
>>   }
>>