Messages in this thread | | | Date | Mon, 18 Oct 2021 13:27:35 +0200 | From | Francesco Dolcini <> | Subject | Re: [PATCH net-next] phy: micrel: ksz8041nl: do not use power down mode |
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On Mon, Oct 18, 2021 at 12:46:14PM +0200, Christophe Leroy wrote: > > > Le 18/10/2021 à 12:18, Francesco Dolcini a écrit : > > Hello Christophe, > > > > On Mon, Oct 18, 2021 at 11:53:03AM +0200, Christophe Leroy wrote: > > > > > > > > > Le 18/10/2021 à 11:42, Francesco Dolcini a écrit : > > > > From: Stefan Agner <stefan@agner.ch> > > > > > > > > Some Micrel KSZ8041NL PHY chips exhibit continous RX errors after using > > > > the power down mode bit (0.11). If the PHY is taken out of power down > > > > mode in a certain temperature range, the PHY enters a weird state which > > > > leads to continously reporting RX errors. In that state, the MAC is not > > > > able to receive or send any Ethernet frames and the activity LED is > > > > constantly blinking. Since Linux is using the suspend callback when the > > > > interface is taken down, ending up in that state can easily happen > > > > during a normal startup. > > > > > > > > Micrel confirmed the issue in errata DS80000700A [*], caused by abnormal > > > > clock recovery when using power down mode. Even the latest revision (A4, > > > > Revision ID 0x1513) seems to suffer that problem, and according to the > > > > errata is not going to be fixed. > > > > > > > > Remove the suspend/resume callback to avoid using the power down mode > > > > completely. > > > > > > As far as I can see in the ERRATA, KSZ8041 RNLI also has the bug. > > > Shoudn't you also remove the suspend/resume on that one (which follows in > > > ksphy_driver[]) > > > > Yes, I could, however this patch is coming out of a real issue we had with > > KSZ8041NL with this specific phy id (and we have such a patch in our linux > > branch since years). > > > > On the other hand the entry for KSZ8041RNLI in the driver is somehow weird, > > since the phy id according to the original commit does not even exists on > > the datasheet. Would you be confident applying such errata for that phyid > > without having a way of testing it? > > > If your patch was to add the suspend/resume capability I would agree with > you, but here we are talking about removing it, so what risk are we taking ? yes, you are right.
> In addition, commit 4bd7b5127bd0 ("micrel: add support for KSZ8041RNLI") > clearly tells that the only thing it did was to copy KSZ8041NL entry, so for > me updating both entries would really make sense. > > It looks odd to me that you refer in your commit log to an ERRATA that tells > you that the bug also exists on the KSZ8041RNLI and you apply it only > partly.
I think I was not clear enough, the entry I changed should already cover KSZ8041RNLI, the phyid is supposed to be just the same according to the datasheet. This entry for KSZ8041RNLI seems really special with this un-documented phyid. But I'm just speculating, I do not have access to these hardware.
Said that if there are no concern from anybody else, to be on the safe/cautious side, I can just update also this entry.
Francesco
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