[U-Boot] U-Boot on Minnowboard Max

[George McCollister]

On Thu, Jun 9, 2016 at 11:01 PM, Bin Meng <bmeng.cn at gmail.com> wrote:
> Hi,
>
> +Simon, ML and Stefan.
>
> On Wed, Jun 8, 2016 at 11:58 PM, vinoth eswaran <evinoth1206 at gmail.com> wrote:
>> Hello Bin,
>>
>>   Sorry that I don't know how not to reply without top-posting. I
>> don't know which settings to change, google didn't help me in this
>> case.
>>
>
> It's a posting style. See https://en.wikipedia.org/wiki/Posting_style.
> We use bottom-posting.
>
>> I have tested your patch on my target and found out that now mounting
>> root file system by sd card is fine. Thanks a lot :)
>>
>
> Great!
>
>> Now I am seeing another issue , the USB3.0 port (bottom) is not
>> working. I am sure that both ports are working fine with UEFI
>> Firmware. I tested by connecting a mouse to the USB port , in the
>> USB2.0 port (upper) it is working fine but in the USB3.0 port the
>> mouse is not getting detected. I am not sure why it is happening. I
>> looked into the kernel logs but I didn't get any error/debug messages.
>> Can you please check this on your board also.
>>
>
> Do you mean xHCI is not working under U-Boot? xHCI is not enabled in
> U-Boot yet. IIRC, U-Boot's xHCI driver does not support Intel
> controller yet.
I think he just means the bottom port isn't working. I had a patch set
to fix the problem but I never had time re-work the first patch in the
series.
http://lists.denx.de/pipermail/u-boot/2015-October/229469.html

>
>> Do you have any documents regarding the u-boot to kernel handover,
>> what all informations does u-boot  handover to Linux Kernel. It would
>> be great help.
>
> This is documented in kernel doc:
> https://www.kernel.org/doc/Documentation/x86/boot.txt
>
>> I thought that the MMC driver issue is on Linux Kernel side, but it
>> was some offset and probing issue in the u-boot.
>>
>
> Umm, it's hard to tell. Starting from BayTrail, Intel's SoC is more
> and more like an ARM SoC, with many GPIOs and pinmux that needs to be
> configured. Linux kernel does provide driver for the BayTrail pinctrl,
> but so far no mainline driver is making use of it. The generic x86
> kernel image is not aware of any board-specific I/O configuration so
> some peripherals (like in this case the SD controller) won't work out
> of the box. The mainline Linux kernel expects the underlying
> bootloader to do the I/O configuration, IOW, kernerl is not bootloader
> agnostic yet on x86. It relies on whatever bootloader (UEFI BIOS,
> coreboot, U-Boot) to do such kind of work.
>
> Regards,
> Bin
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