Disabling autoneg and enforcing speed/duplex

Hi,

I'm using the Kirkwood Ethernet controller (mv643xx_eth.c) with a Marvell 88E3018 PHY which needs to be set in forced 100Base-TX mode.

Thanks to Sebastian's addition of DT support to the ethernet driver, I can easily set speed and duplex within the ethernet's port node, therefore leaving the phy unmanaged -- this works fine (I guess this mode is set on the phy by the bootloader or by strap settings).

However, this PHY has an erratum whose workaround requires some registers be written -- I believe the natural solution would be to start managing the PHY (i.e. set "phy-handle") and implement the proper workaround within drivers/net/phy/marvell.c. Making the PHY managed does however enable autoneg and therefore break everything.

Which brings me to my question: shouldn't there be a way to specify some forced settings within the PHY's node for such cases?

Only thing I found vaguely resembling what I'm looking for is Florian's patch introducing "max-speed" in the PHY -- not quite the same thing though. Which, if I understand it correctly, implements it as a property of the PHY, whereas ePAPR specifies it as a property of the ethernet device (which makes sense, since you might want to connect a 10/100 MII to a 10/100/1000 PHY and therefore have the MII restrict the capabilities of the PHY).

Or perhaps I'm missing some important bits here?

Thanks!
Gerlando
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Quoted 19 lines · Gerlando Falauto

Hi,

I'm using the Kirkwood Ethernet controller (mv643xx_eth.c) with a Marvell 88E3018 PHY which needs to be set in forced 100Base-TX mode.

Thanks to Sebastian's addition of DT support to the ethernet driver, I can easily set speed and duplex within the ethernet's port node, therefore leaving the phy unmanaged -- this works fine (I guess this mode is set on the phy by the bootloader or by strap settings).

However, this PHY has an erratum whose workaround requires some registers be written -- I believe the natural solution would be to start managing the PHY (i.e. set "phy-handle") and implement the proper workaround within drivers/net/phy/marvell.c. Making the PHY managed does however enable autoneg and therefore break everything.

Which brings me to my question: shouldn't there be a way to specify some forced settings within the PHY's node for such cases?

Quoted 6 lines

Only thing I found vaguely resembling what I'm looking for is Florian's patch introducing "max-speed" in the PHY -- not quite the same thing though. Which, if I understand it correctly, implements it as a property of the PHY, whereas ePAPR specifies it as a property of the ethernet device (which makes sense, since you might want to connect a 10/100 MII to a 10/100/1000 PHY and therefore have the MII restrict the capabilities of the PHY).

You shouldn't need a property in this case. The driver knows what the h/w is limited to and can configure the phy based on that.

It is when
both sides should support a higher speed and you need to limit it for some other reason like errata or board level configuration.

Quoted 1 line

Or perhaps I'm missing some important bits here?

Does this patch help you:

https://lkml.org/lkml/2014/1/15/533

Rob

Quoted 7 lines

Thanks!
Gerlando
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