From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Wed, 18 Dec 2019 05:48:11 +0100 Subject: [U-Boot] [PATCH] net/phy: Fix phy_connect() for phy addr 0 In-Reply-To: References: <20191105040439.23450-1-priyanka.jain@nxp.com> <20191107191543.GK19317@bill-the-cat> <423b0427-c8b3-8e2e-d64c-ae06d79214b6@denx.de> <4cecdc1d-cf11-e26f-0bb9-deeeb2bd4d95@denx.de> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 12/18/19 3:06 AM, Joe Hershberger wrote: > On Tue, Dec 17, 2019 at 1:04 PM Marek Vasut wrote: >> >> On 12/17/19 7:47 PM, Joe Hershberger wrote: >>> On Tue, Dec 17, 2019 at 11:46 AM Marek Vasut wrote: >>>> >>>> On 12/17/19 5:25 PM, Joe Hershberger wrote: >>>>> Hi Marek, >>>> >>>> Hi Joe, >>>> >>>>> On Tue, Dec 17, 2019 at 1:39 AM Marek Vasut wrote: >>>>>> >>>>>> On 11/7/19 9:04 PM, Joe Hershberger wrote: >>>>>>> On Thu, Nov 7, 2019 at 1:16 PM Tom Rini wrote: >>>>>>>> >>>>>>>> On Tue, Nov 05, 2019 at 04:05:11AM +0000, Priyanka Jain wrote: >>>>>>>> >>>>>>>>> Fix 'mask' calculation in phy_connect() for phy addr '0'. >>>>>>>>> 'mask' is getting set to '0xffffffff' for phy addr '0' >>>>>>>>> in phy_connect() whereas expected value is '0'. >>>>>>>>> >>>>>>>>> >>>>>>>>> Signed-off-by: Priyanka Jain >>>>>>>> >>>>>>>> Reported-by: tetsu-aoki via github >>>>>>> >>>>>>> Acked-by: Joe Hershberger >>>>>> >>>>>> Sadly, this breaks systems where a PHY is at address 0. >>>>>> I have such an STM32MP1 system with LAN8720 PHY and since this patch, I >>>>>> cannot use ethernet. Please revert. >>>>> >>>>> It seems like a case that shouldn't have worked before. >>>> >>>> Eh? PHY at address 0 definitely did work before and must work now. >>> >>> Agreed that a phy at address 0 should work. Not agreed that because >>> the value "0" used to work due to a bug that it must still. Which of >>> these is the statement you are making? Do we already agree or >>> disagree? >> >> I am saying that because a board worked on rc4 and does not work on rc5, >> this is a bug introduced by this patch in rc5 and must be fixed before >> the release. >> >> The address 0 is a PHY broadcast address for some PHYs, it's a fixed >> address for other PHYs. Thus, a PHY at address 0 must work. If this is >> broken now, it's a bug. > > The only thing this patch should change is to not access addresses > other than 0. I read the data sheet for the LAN8720 and it doesn't > mention anything about any broadcast behavior, so I'm not sure what > you're trying to state here. Read [1] section 3.7.1 PHYAD[2:0]: PHY ADDRESS CONFIGURATION What I am saying is that there are two types of PHYs, ones which treat PHY address 0 as broadcast and ones which treat it as regular address. This one is the later and is configured as such in my case. http://ww1.microchip.com/downloads/en/DeviceDoc/00002164B.pdf >>>>> What about >>>>> this board requires the mask to be all 'f's, other than specifying the >>>>> wrong phy address? It seems that in your case the phy address is not >>>>> actually 0 (or the computed mask would find it), but your board dts >>>>> may be setting it to 0 as an "unknown" value, but the correct unknown >>>>> value should be "-1". It seems the issue is with these boards. >>>> >>>> Nope, the address is actually configured to 0 in hardware. >>> >>> Can you double check that? >> >> No, sorry, I know the hardware is fixed to 0. Checking it again will not >> change this fact. > > It seems there is no phy driver for this in U-Boot so the generic > behavior is being used. I'm at a disadvantage of not having this board > to try. Can you revert this patch and run with debug enabled for > drivers/net/phy/phy.c to determine what is happening for this board? I > would appreciate you helping with this. It only says "connected to Generic PHY" . So looking at the commit message, I am not really sure which board or issue does this patch fix. But if I understand the commit message right, then the aim is to set mask to 0 instead of 0xffffffff for address 0. But that's not right either, the mask should be BIT(0) = 1 for address 0, and that's what the patch actually does. I guess this then fails somewhere further down the road ...