Messages in this thread | | | Date | Wed, 28 Nov 2018 19:01:14 -0800 (PST) | Subject | Re: macb: probe of 10090000.ethernet failed with error -110 | From | Palmer Dabbelt <> |
| |
On Wed, 28 Nov 2018 18:28:58 PST (-0800), andrew@lunn.ch wrote: >> This is all fine as long as Linux doesn't go and reset the phy again. Until >> bafbdd527d56 ("phylib: Add device reset GPIO support") was the case. After >> that commit I believe phylib is resetting the phy while attempting to enter >> unmanaged mode, which is now allowed in this particular chip. >> >> Since it appears the phy is not usually described by the device tree but is >> instead discovered by probing a MII-based ID register, it seems the best >> place to put this is within the phy driver itself. I find it's usually best >> to describe things with code, so I hacked up something like > > Talking to Florian, i was under the impression that you could not even > discover the device when its reset state what wrong. You could not > read the ID registers. > > Your suggested change assumed you can discover the device. Is this > true?
Sorry, I can't tell that from reading the code. Since our bootloader resets the phy into unmanaged mode I think that just deasserting reset should be OK, but I don't have much confidence in that -- once I run into one unexpected feature I start to expect more :)
It looks like there's already an expectation that at least the phy ID registers can be read between falling and rising edges of a reset, as that's how the fixups are handled. Since the error message that shows up with a single (single as far as Linux is concerned, triple since a cold boot) reset rising edge still lists the phy by name I think that probing is working well enough, but I wouldn't be surprised if there's something in the middle that's gone wrong. It's possible registering a fixup that does the double reset can get us through the probing sequence.
Maybe Atish or Paul can help out? I'm a bit embarrassed to admit that I can't actually figure out how to boot the board any more, it's been a year since it's been my primary target and since I just to arch/riscv stuff now I rely them to test on the board...
| |