Messages in this thread | | | Date | Fri, 26 Aug 2022 21:51:29 +0200 | From | Andrew Lunn <> | Subject | Re: [PATCH net-next] net: phy: micrel: Adding SQI support for lan8814 phy |
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> > > In lan8814 phy only channel 0 is used for 100base-tx. So returning SQI > > > value for channel 0. > > > > What if the other pairs are bad? Maybe Oleksij has an opinion here. > > > > Also 100baseTX (and 10baseT) has two pairs, one for transmitting and one > > for receiving. I guess you meassure the SQI on the receiving side. So is > > channel 0 correct here? > > > > Again this is the first time I hear about SQI but it puzzles me that > > it only evaluate one pair in this case. So as a user who reads this > > SQI might be misleaded. > > Wow! I was so possessed with one-pair networks, that forgot to image > that there is 1000Base-T with more then one pairs :D > > Yes, your are right. We wont to have readings from all RX channels and > be able to export them to the user space. In fact, if i see it > correctly, the LAN8814_DCQ_CTRL_CHANNEL_MASK value should be synced with > the MDI-X state. Otherwise we will be reading TX channels.
I don't know if i should trust the datasheet i found, but it suggests the register in MMD device 1 space has a field to indicate which cable pair should be measured. So for 1000Base-T all pairs are both Rx and Tx, so i would expect 4 values are returned. That then might need an uAPI extension, if you were focused on T1 :-)
Andrew
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