Re: [PATCH V3 1/3] net: stmmac: Fix PTP ref clock for Tegra234

[Krzysztof Kozlowski <krzk@kernel.org>]

On 31/03/2026 12:14, Jon Hunter wrote:
> 
> On 26/03/2026 08:32, Krzysztof Kozlowski wrote:
> 
> ...
> 
>>> @@ -257,9 +258,23 @@ static int tegra_mgbe_probe(struct platform_device *pdev)
>>>   	if (!mgbe->clks)
>>>   		return -ENOMEM;
>>>   
>>> -	for (i = 0; i <  ARRAY_SIZE(mgbe_clks); i++)
>>> +	/*
>>> +	 * Older device-trees use 'ptp-ref' rather than 'ptp_ref'.
>>> +	 * Fall back to the legacy name when 'ptp_ref' is absent.
>>> +	 */
>>> +	use_legacy_ptp = of_property_match_string(pdev->dev.of_node,
>>> +						  "clock-names", "ptp_ref") < 0;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(mgbe_clks); i++) {
>>>   		mgbe->clks[i].id = mgbe_clks[i];
>>>   
>>> +		if (use_legacy_ptp && !strcmp(mgbe_clks[i], "ptp_ref")) {
>>
>> Why index 0 is not valid? And why -EINVAL would be considered as legacy
>> clock present?
> 
> Index 0 is valid. However, yes I guess that treating an -EINVAL from 
> of_property_match_string() is not correct. I will switch the logic to be ...
> 
>   use_legacy_ptp = of_property_match_string(pdev->dev.of_node,
>                                     "clock-names", "ptp-ref") >= 0;

No, apologies, I think my comment was not correct and your reply made me
rethink. I missed final "< 0" in of_property_match_string().

So the code is good, you do not store index in 'use_legacy_ptp', but the
error return value.

Can you however make it more obvious code, so something like:

if (of_property_match_string...))
	use_legacy_ptp = true;;



Best regards,
Krzysztof