Trying to boot custom kernel on Wink Hub (i.MX28)

[Rogan Dawes]

Hi Fabio,

As far as I am aware, the U-boot source for the Wink hub has not been
made available anywhere. That said, the RAM chip in use on the board
is marked D9LPX, which apparently corresponds to the following item:
https://media-www.micron.com/-/media/client/global/documents/products/data-sheet/dram/ddr2/512mbddr2.pdf?rev=2c70f8a2b207452584b2bf040de8d771

I did try to change the iomux_cfg_t as suggested above, built using
make mx28evk_defconfig && make u-boot.sb, and used mxsldr to try load
it, to no avail. There was no output on the serial port at all, or any
other suggestion that anything was running.

Any other suggestions?

Regards,

Rogan

On Tue, 22 Aug 2023 at 04:33, Fabio Estevam <festevam at gmail.com> wrote:
>
> Hi Rogan,
>
> On Fri, Aug 18, 2023 at 10:45 AM Rogan Dawes <rogan at dawes.za.net> wrote:
> >
> > Circling back to this, I wanted to get a modern u-boot running on the
> > Wink Hub v1 as well. Since it is possible to invoke SDP over USB
> > (having soldered on a suitable microUSB connector), I have no concern
> > about bricking it now. It's also a LOT easier than JTAG!
> >
> > I tried to build and flash the mx28evk_defconfig, but failed to get
> > any output on the serial console. This is likely to be unsurprising,
> > due to the already established alternative configuration of the UART
> > identified by Fabio.
> >
> > I then patched imx28.dtsi to add duart_pins_c as per Fabio's previous
> > patch for the Linux kernel:
> >
> > + duart_pins_c: duart at 2 {
> > + reg = <2>;
> > + fsl,pinmux-ids = <
> > + MX28_PAD_I2C0_SCL__DUART_RX
> > + MX28_PAD_I2C0_SDA__DUART_TX
> > + >;
> > + fsl,drive-strength = <MXS_DRIVE_8mA>;
> > + fsl,voltage = <MXS_VOLTAGE_HIGH>;
> > + fsl,pull-up = <MXS_PULL_DISABLE>;
> > + };
> > +
> >
> > And updated mx28evk_defconfig to use duart_pins_c instead of
> > duart_pins_a. However, I still got no output after using:
> >
> > sudo $(which snagrecover) --soc imx28 -f
> > src/snagrecover/templates/imx28-evk.yaml
>
> I am not familiar with this tool. I was only aware of the one below:
>
> https://source.denx.de/denx/mxsldr
>
> Are you able to load the original vendor U-Boot with it?
>
> Also, is the original vendor U-Boot source code available?
>
> It is important to re-use the same DDR initialization from the original U-Boot.
>
> > with u-boot.sb in the current directory.
> >
> > I also tried using the complete imx28-wink-hub-v1.dts as created by
> > Fabio, and updated the .config to reference that instead of the
> > imx28-evk, but I suspect that I may not have made the updates
> > sufficiently well, if the name of the board needs to correspond with
> > any details of the device tree? Neither of these resulted in any
> > output.
> >
> > Any other suggestions?
>
> Please check board/freescale/mx28evk/iomux.c:
>
> const iomux_cfg_t iomux_setup[] = {
> /* DUART */
> MX28_PAD_PWM0__DUART_RX,
> MX28_PAD_PWM1__DUART_TX,
>
> The DUART pins need to be changed here as well.