Re: [PATCH v3 3/4] hw/arm: sabrelite: Connect the Ethernet PHY at address 6

[Bin Meng]

On Sun, May 2, 2021 at 7:21 AM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 5/1/21 2:40 PM, Philippe Mathieu-Daudé wrote:
> > On 5/1/21 10:12 PM, Guenter Roeck wrote:
> >> On 4/30/21 9:28 PM, Bin Meng wrote:
> >>> On Fri, Apr 30, 2021 at 10:41 PM Guenter Roeck <linux@roeck-us.net> wrote:
> >>>>
> >>>> Hi,
> >>>>
> >>>> On Wed, Jan 06, 2021 at 02:35:03PM +0800, Bin Meng wrote:
> >>>>> From: Bin Meng <bin.meng@windriver.com>
> >>>>>
> >>>>> At present, when booting U-Boot on QEMU sabrelite, we see:
> >>>>>
> >>>>>   Net:   Board Net Initialization Failed
> >>>>>   No ethernet found.
> >>>>>
> >>>>> U-Boot scans PHY at address 4/5/6/7 (see board_eth_init() in the
> >>>>> U-Boot source: board/boundary/nitrogen6x/nitrogen6x.c). On the real
> >>>>> board, the Ethernet PHY is at address 6. Adjust this by updating the
> >>>>> "fec-phy-num" property of the fsl_imx6 SoC object.
> >>>>>
> >>>>> With this change, U-Boot sees the PHY but complains MAC address:
> >>>>>
> >>>>>   Net:   using phy at 6
> >>>>>   FEC [PRIME]
> >>>>>   Error: FEC address not set.
> >>>>>
> >>>>> This is due to U-Boot tries to read the MAC address from the fuse,
> >>>>> which QEMU does not have any valid content filled in. However this
> >>>>> does not prevent the Ethernet from working in QEMU. We just need to
> >>>>> set up the MAC address later in the U-Boot command shell, by:
> >>>>>
> >>>>>   => setenv ethaddr 00:11:22:33:44:55
> >>>>>
> >>>>
> >>>> With this patch in place, the standard Ethernet interface no longer 
> >>>> works when
> >>>> booting sabrelite Linux images directly (without u-boot) using the 
> >>>> following
> >>>> qemu command.
> >>>>         qemu-system-arm -M sabrelite -kernel arch/arm/boot/zImage
> >>>>         ...
> >>>>
> >>>> The Ethernet interface still instantiates, but packet transfer to the 
> >>>> host
> >>>> no longer works. Reverting this patch fixes the problem for me.
> >>>>
> >>>> Is there a qemu command line parameter that is now necessary to 
> >>>> instantiate
> >>>> the Ethernet interface when booting Linux ?
> >>>
> >>> Enabling "guest_errors" shows that Linux kernel fec driver is trying
> >>> to read PHY at address 0, which is not what we want.
> >>>
> >>> [imx.fec.phy]imx_phy_read: Bad phy num 0
> >>>
> >>> The device tree blob of the sabrelite does not contain a node for the
> >>> ethernet phy specifying phy address, so I suspect Linux kernel driver
> >>> is using default phy address 0 instead.
> >>>
> >>> Could you please test on a real hardware to see what happens?
> >>>
> >>
> >> The problem is that qemu returns 0 when the OS tries to read from a
> >> non-existing PHY. Linux expects it to return 0xffff, and believes that
> >> a PHY is there if 0 is returned.
> >
> > Correct.
> >
>
> I'll send a patch. Next question is why the Ethernet interfaces on 
> mcimx6ul-evk
> and mcimx7d-sabre don't work. I either get no connectivity at all (similar to
> the above) or something like
>
> fec 2188000.ethernet eth1: Unable to connect to phy
> ifconfig: SIOCSIFFLAGS: No such device
>
> Any idea ?

I don't see these 2 are supported targets of QEMU:
https://wiki.qemu.org/Documentation/Platforms/ARM

Regards,
Bin