On Thu, 24 Jan 2019 at 23:51, Sergey Kubushyn <k...@koi8.net> wrote: > On Fri, 4 Jan 2019, Chris Spencer wrote: > Hi Chris, > > Did you figure out what was wrong with the PHY always reading zeroes over > MDIO? > > I have exactly same problem here with out i.MX8MQ-based device -- it worked > just fine with older U-Boot without DM_ETH but always reads zeroes over MDIO > with 2019.01... > > I'm still fighting and will probably find the culprit but it would've saved > me some time if you had found what was wrong... > > Your reply is highly appreciated. > > My best regards, > Sergey.
Hi Sergey, I never quite got to the bottom of why it doesn't work in U-Boot, but I did discover that U-Boot's failure to correctly initialise the Ethernet controller is what was breaking the Linux driver. Basically, it's leaving behind an 'unspent' transfer request in the ENET_MMFR register (otherwise known as FEC_MII_DATA in the Linux driver) which gets triggered when the Linux driver starts initialising the Ethernet controller. This has a nasty habit of interfering with the first transfer request the driver tries to make. If you don't need networking in U-Boot then you can just set CONFIG_CMD_NET=n in your build config and that will fix the Linux driver. I'm afraid I can't offer any further insight if you do need networking in U-Boot. Thanks, Chris _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
