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SubjectRe: BCM54220: After the BCM54220 closes the auto-negotiation, the configuration forces the 1000M network port to be linked down all the time.
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On 2/21/2023 11:41 AM, Andrew Lunn wrote:
> On Tue, Feb 21, 2023 at 10:44:44AM -0800, Doug Berger wrote:
>> On 2/17/2023 12:06 AM, Wang, Xiaolei wrote:
>>> hi
>>>
>>> When I use the nxp-imx7 board, eth0 is connected to the PC, eth0 is turned off the auto-negotiation mode, and the configuration is forced to 10M, 100M, 1000M. When configured to force 1000M,
>>> The link status of phy status reg(0x1) is always 0, and the chip of phy is BCM54220, but I did not find the relevant datasheet on BCM official website, does anyone have any suggestions or the datasheet of BCM54220?
>>>
>>> thanks
>>> xiaolei
>>>
>> It is my understanding that the 1000BASE-T PHY requires peers to take on
>> asymmetric roles and that establishment of these roles requires negotiation
>> which occurs during auto-negotiation. Some PHYs may allow manual programming
>> of these roles, but it is not standardized and tools like ethtool do not
>> support manual specification of such details.
>
> Are you talking about ethtool -s [master-slave|preferred-master|preferred-slave|forced-master|forced-slave]
>
I am, though I was not aware of their addition to ethtool and I avoided
referencing them by name out of an overabundance of political
correctness ;).

Thanks for bringing this to my attention.

> The broadcom PHYs call genphy_config_aneg() -> __genphy_config_aneg()
> -> genphy_setup_master_slave() which should configure this, even when
> auto-neg is off.
Yes, this sounds good. Perhaps Xiaolei is not setting these properly
when forcing 1000.

>
> Andrew
Thanks again!
Doug

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