On 04/11/2016 17:55, Måns Rullgård wrote: > Florian Fainelli <f.faine...@gmail.com> writes: > >> On 11/04/2016 08:22 AM, Måns Rullgård wrote: >>> Andrew Lunn <and...@lunn.ch> writes: >>> >>>> On Fri, Nov 04, 2016 at 03:05:00PM +0000, Måns Rullgård wrote: >>>>> Andrew Lunn <and...@lunn.ch> writes: >>>>> >>>>>>>> I agree with you. But fixing it is likely to break boards which >>>>>>>> currently have "rgmii", but actually need the delay in order to work. >>>>>>> >>>>>>> Does the internal delay here refer to the PHY or the MAC? It's a >>>>>>> property of the MAC node after all. >>>>>> >>>>>> It is the PHY which applies the delay. >>>>> >>>>> Says who? >>>> >>>> The source code. >>> >>> There's source code that disagrees with that. The Broadcom GENET >>> driver, for instance. >> >> Correct, and in the case where the MAC adds the delay while transmitting >> (because it supports that) the expectation is that the PHY would remove >> such a delay internally, conversely, the PHY would introduce a delay >> while transmitting back to the PHY, in order to produce the desired 90 >> degrees shift on the RGMII signals, and get reproduce the correct clock >> and data alignment internally. >> >>> >>>>> Some MACs can do it too. >>>> >>>> I'm sure they can. But look at the code. Nearly none do, and those >>>> that do are potentially broken. >>> >>> Those few drivers that do anything differently based on these values >>> enable clock delay in the MAC. That's why I wrote the NB8800 driver the >>> way I did. >>> >> >> I don't really what is wrong with the nb8800 driver at the moment, so >> maybe this is just a configuration issue with the Atheros PHY driver, >> it's not like it has not given people headache judging by the recent >> discussions... > > We don't even know if the problems Mason is having are caused by > incorrect clock skew in the first place. I'd suggest not patching > anything at all until he gets it working.
All I said was: > Assuming that "rxid" (rx internal delay) and "rx clock delay" are > in fact the same concept with different names, do you agree that > it would be unexpected for "rgmii rx clock delay" to be enabled > when a DTB specifies "rgmii" or "rgmii-txid" ? In parallel, Sebastian changed the DT of a 8758 board from phy-connection-type = "rgmii"; to phy-connection-type = "rgmii-txid"; and this broke the Ethernet on 8758, although the "reference" legacy 3.4 kernel does enable tx clock delay. Regards.
