[U-Boot] U-Boot on Minnowboard Max

[vinoth eswaran]

On Fri, Jun 10, 2016 at 2:53 PM, George McCollister
<george.mccollister at gmail.com> wrote:
> 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
>
Ya that's exactly is the problem. I will try to use the patch , but I
am seeing many updates on the 'intel_ich6_gpio.c' which is hard to
understand for me.

>>
>>> 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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