On 18.03.2021 17:02, Florian Fainelli wrote: > > > On 3/18/2021 6:25 AM, Heiner Kallweit wrote: >> On 18.03.2021 10:09, Wong Vee Khee wrote: >>> When using Clause-22 to probe for PHY devices such as the Marvell >>> 88E2110, PHY ID with value 0 is read from the MII PHYID registers >>> which caused the PHY framework failed to attach the Marvell PHY >>> driver. >>> >>> Fixed this by adding a check of PHY ID equals to all zeroes. >>> >> >> I was wondering whether we have, and may break, use cases where a PHY, >> for whatever reason, reports PHY ID 0, but works with the genphy >> driver. And indeed in swphy_read_reg() we return PHY ID 0, therefore >> the patch may break the fixed phy. >> Having said that I think your patch is ok, but we need a change of >> the PHY ID reported by swphy_read_reg() first. >> At a first glance changing the PHY ID to 0x00000001 in swphy_read_reg() >> should be sufficient. This value shouldn't collide with any real world >> PHY ID. > > It most likely would not, but it could be considered an ABI breakage, > unless we filter out what we report to user-space via SIOGCMIIREG and > /sys/class/mdio_bus/*/*/phy_id > > Ideally we would have assigned an unique PHY OUI to the fixed PHY but > that would have required registering Linux as a vendor, and the process > is not entirely clear to me about how to go about doing that. > -- In the OUI list I found entry 58-9C-FC, belonging to FreeBSD Foundation. Not sure what they use it for, but it seems adding Linux as a vendor wouldn't be a total exception. > Florian > Heiner
