Hi Nikolay, On Mon, May 4, 2015 at 1:18 AM, Nikolay Dimitrov <picmas...@mail.bg> wrote: > Hi Fabio, > > On 05/04/2015 06:30 AM, Fabio Estevam wrote: >> >> From: Fabio Estevam <fabio.este...@freescale.com> >> >> mx6cuboxi sometimes fails to recognize the Ethernet PHY: >> >> Net: Phy 0 not found >> >> The explanation comes from a patch from Rabeeh: >> >> "The LED_ACT pin on the carrier-one boards had a pull down that >> forces the phy address to 0x0; where on CuBox-i and the production >> HummingBoard that pin is connected directly to LED that depending on >> the pull down strength of the LED it might be sampled as '0' or '1' >> thus the phy address might appear as either address 0x0 or 0x4." > > > There's no such thing as "LED pull-down". The forward voltage drop of a > LED is between 1.65V (red low-power LEDs) to 2.1V (green LEDs) to even > more for blue LEDs. Even the lowest Vf doesn't qualify as logic "0" for > LVCMOS33, which is around 1V max (Vil). The LED just can't pull-down the > voltage level low enough. > > So, unless you have some control over the pin (via a programmable > on-chip pull-up or pull-down) which I doubt as it's a PHY pin, the > actual behavior is that the pin is floating, and samples a random value > at boot. Which means, the hardware is just buggy.
As mentioned in the commit log this explanation comes from Solid-run. The key point here is that the PHY can appear at 0x0 and 0x4, so this patch handles such case. Regards, Fabio Estevam _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot