Re: [PATCH net v2] net: dpaa: fix mode setting

["Michael Walle" <mwalle@kernel.org>]

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On Fri Jul 17, 2026 at 2:44 PM CEST, Paolo Abeni wrote:
> On 7/17/26 2:05 PM, Sean Anderson wrote:
>> On 7/17/26 07:11, Paolo Abeni wrote:
>>> On 7/17/26 12:13 PM, Michael Walle wrote:
>>>> I've seen that, but.. that was the actual change between v1 and v2
>>>> as suggested by Sean. It does not depend on the actual link speed,
>>>> but the maximum link speed. So it is not relevant if the link
>>>> negotiates to a slower speed or not. At least that now matches the
>>>> behavior prior to the phylink conversion. If that was working -
>>>> that I can't tell you.
>>>
>>> I'm sorry, following all cross revision discussion is a bit hard here.
>>>
>>> I don't understand if the 'link never established' is specific of your
>>> board, or it a constant with this driver. Could you please clarify?

I don't think it's related to my board, but rather to the link being
a SGMII one on my board. I assume Sean had an RGMII link while
converting the driver (?) and moreover, that it worked correctly
there :)

>> I think we should set byte/nibble mode in link_up as well as mac_config. That
>> should fix the problem where the link never comes up (possibly broken since
>> the phylink conversion). I think it's unlikely that this config is supposed
>> to match the phy interface speed and not the link speed, but you never know...
> FTR, the above does not answer my question ;)
>
> Still I think (mostly guess) bringing the mode initialization in both
> link_up and mac_config should be safer (that is, I agree with the above
> plan).

I agree. I looked at the original driver and there adjust_link()
will also select between byte and nibble mode. I'll prepare a v3.

Sorry, I misunderstood Sean's intention/suggestion, thanks for
pushing on this. FWIW, I also tried with nibble mode as the initial
configuration on my board and link_up() is getting called. Whereas
if it's 0 (as in being documented as "reserved", though it's the
default), .link_up() is never called. Thus, it seems that it just
has to be any valid setting until link_up() will set the correct
value.

-michael

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