Re: [PATCH] w5100: restore GPIO-based link detection

On Wed, Aug 05, 2026 at 12:46:14PM +0200, Arnd Bergmann wrote:
>On Wed, Aug 5, 2026, at 11:44, Arthur Crépin Leblond wrote:
>> On Wed, Aug 05, 2026 at 11:11:53AM +0200, Arnd Bergmann wrote:
>> You're right for the W5100 that would not make any sense during data
>> transfers it would trigger the interrupt. That's unreliable.
>>
>> I am using the W5500, and in the datasheet it says
>>
>>    Link LED
>>    This shows the Link status.
>>    Low: Link is established
>>    High: Link is not established
>>
>> I can confirm it is what is happening, I don't see any changes
>> of state during TX/RX.
>
>Ok, good. On the other hand, the W5500 also has a PHYCFG register
>that should tell you the link status without looking at the
>GPIO line, though it's not clear if the CON/DISCON interrupt
>fires on link state change in MACRAW mode.
>
>It probably makes sense to wire up link w5100_get_link() to
>the phy register for w5500 either way, as that works without
>connecting a GPIO. Then you can just describe the LINKLED
>signal as an optional interrupt in the DT binding to trigger
>checking the link state in that register.
>
>     Arnd

Seems to work, the PHYCFG[0] bit gets updated on link change.

Arthur