[U-Boot] [PATCH v4] x86: baytrail: Configure FSP UPD from device tree

[Bin Meng]

Hi Simon,

On Tue, Aug 11, 2015 at 11:07 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Bin,
>
> On 10 August 2015 at 20:53, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Hi Andrew,
>>
>> On Mon, Aug 10, 2015 at 7:32 PM, Andrew Bradford
>> <andrew at bradfordembedded.com> wrote:
>>> Hi Bin,
>>>
>>> On 08/09 10:52, Bin Meng wrote:
>>>> Hi Andrew,
>>>>
>>>> On Sun, Aug 9, 2015 at 9:08 AM, Andrew Bradford
>>>> <andrew at bradfordembedded.com> wrote:
>>>> > Hi Simon,
>>>> >
>>>> > On 08/08 10:18, Simon Glass wrote:
>>>> >> Hi,
>>>> >>
>>>> >> On 7 August 2015 at 06:44, Bin Meng <bmeng.cn at gmail.com> wrote:
>>>> >> > On Fri, Aug 7, 2015 at 8:36 PM, Andrew Bradford
>>>> >> > <andrew at bradfordembedded.com> wrote:
>>>> >> >> From: Andrew Bradford <andrew.bradford at kodakalaris.com>
>>>> >> >>
>>>> >> >> Allow for configuration of FSP UPD from the device tree which will
>>>> >> >> override any settings which the FSP was built with itself.
>>>> >> >>
>>>> >> >> Modify the MinnowMax and BayleyBay boards to transfer sensible UPD
>>>> >> >> settings from the Intel FSPv4 Gold release to the respective dts files,
>>>> >> >> with the condition that the memory-down parameters for MinnowMax are
>>>> >> >> also used.
>>>> >> >>
>>>> >> >> Signed-off-by: Andrew Bradford <andrew.bradford at kodakalaris.com>
>>>> >> >> ---
>>>> >> >>
>>>> >> >
>>>> >> > Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
>>>> >> > Tested-by: Bin Meng <bmeng.cn at gmail.com>
>>>> >> >
>>>> >>
>>>> >> Acked-by: Simon Glass <sjg at chromium.org>
>>>> >> Tested on minnowmax:
>>>> >> Tested-by: Simon Glass <sjg at chromium.org>
>>>> >>
>>>> >> I found that I need to remove two properties from the minnowmax.dts:
>>>> >>
>>>> >> - fsp,enable-xhci needs to be removed as this does not work in U-Boot
>>>> >> at present and stops EHCI from working
>>>> >> - fsp,mrc-debug-msg needs to be removed to prevent debug information
>>>> >> being displayed
>>>> >>
>>>> >> I plan to apply this with these changes - please let me know if this
>>>> >> doesn't suit.
>>>> >
>>>> > I'm OK with disabling xhci and the MRC debug output in the FSP.
>>>> >
>>>> > But if xhci is disabled then I believe when Linux boots that the USB 3.0
>>>> > port on Minnow Max will only act as a USB 2.0 port.  That u-boot doesn't
>>>> > yet have working XHCI on E3800 means there is a tradeoff and I wasn't
>>>> > sure which was a better choice.
>>>>
>>>> Does these xHCI ports on MinnowMax work fully on Linux kernel? If it
>>>> works, I'd rather we keep fsp,enable-xhci in the U-Boot.
>>>
>>> I believe that the xhci port does work on Minnow Max in Linux but I do
>>> not have a board so I'm unable to test, sorry.
>>>
>>
>> OK, my test shows that ehci works fine in U-Boot on Bayley Bay.
>>
>> Hi Simon,
>>
>> What do you think regarding to xhci vs. ehci in U-Boot?
>
> The problem is that USB is then broken in U-Boot. I think it is better
> to limit the speed for the moment until we have that fixed. It is
> quite useful to be able to use a keyboard or USB stick in U-Boot.
>
> With my testing the bottom (blue) port works fine but the top port
> does not. This happens regardless of the xhci setting.

There are 3 ports on Intel Bayley Bay. One USB 3 (blue port) and two
USB 2 ports. The board user guide explicitly mentions that the top USB
2 port does not work and needs PCB rework. For the other two ports,
I've tested U-Boot EHCI stack and it works fine. Interesting to hear
that MinnowMax also has some USB port issue. Maybe the board design is
following Bayley Bay.

>
> So overall I think we are in a better position to go with ehci for
> now, i.e. drop the fsp,enable-xhci property.

OK, then could you please remove this for Bayley Bay as well? Also I
think we need remove the MRC debug output as well.

>
> I think there is a little tweak needed to support both ports, but I
> haven't dug into it yet.
>

This is not possible. According to Intel E3800 datasheet, the xHCI and
EHCI are mutually exclusive. We can either use xHCI, or EHCI.

Regards,
Bin