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

From: Bin Meng <bmeng.cn@gmail.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
	"Bin Meng" <bin.meng@windriver.com>,
	"qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>,
	"Jean-Christophe Dubois" <jcd@tribudubois.net>,
	qemu-arm <qemu-arm@nongnu.org>,
	"Alex Bennée" <alex.bennee@linaro.org>
Subject: Re: [PATCH v3 3/4] hw/arm: sabrelite: Connect the Ethernet PHY at address 6
Date: Sat, 1 May 2021 12:28:30 +0800	[thread overview]
Message-ID: <CAEUhbmUTLecMcr0=vmBeYJZeK6CdZY4SZcYiOu0E9AawY41+Cg@mail.gmail.com> (raw)
In-Reply-To: <20210430144136.GA2880420@roeck-us.net>

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?

Regards,
Bin