Re: Probe failure of usb controller @11290000 on MT8195 after next-20231221

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 11/07/24 06:13, Macpaul Lin ha scritto:
> 
> 
> On 7/11/24 03:15, Nícolas F. R. A. Prado wrote:
>> On Fri, Jan 19, 2024 at 10:12:07AM +0100, AngeloGioacchino Del Regno wrote:
>>> Il 18/01/24 19:36, Nícolas F. R. A. Prado ha scritto:
>>>> Hi,
>>>>
>>>> KernelCI has identified a failure in the probe of one of the USB controllers on
>>>> the MT8195-Tomato Chromebook [1]:
>>>>
>>>> [   16.336840] xhci-mtk 11290000.usb: uwk - reg:0x400, version:104
>>>> [   16.337081] xhci-mtk 11290000.usb: xHCI Host Controller
>>>> [   16.337093] xhci-mtk 11290000.usb: new USB bus registered, assigned bus 
>>>> number 5
>>>> [   16.357114] xhci-mtk 11290000.usb: clocks are not stable (0x1003d0f)
>>>> [   16.357119] xhci-mtk 11290000.usb: can't setup: -110
>>>> [   16.357128] xhci-mtk 11290000.usb: USB bus 5 deregistered
>>>> [   16.359484] xhci-mtk: probe of 11290000.usb failed with error -110
>>>>
>>>> A previous message [2] suggests that a force-mode phy property that has been
>>>> merged might help with addressing the issue, however it's not clear to me how,
>>>> given that the controller at 1129000 uses a USB2 phy and the phy driver patch
>>>> only looks for the property on USB3 phys.
>>>>
>>>> Worth noting that the issue doesn't always happen. For instance the test did
>>>> pass for next-20240110 and then failed again on today's next [3]. But it does
>>>> seem that the issue was introduced, or at least became much more likely, between
>>>> next-20231221 and next-20240103, given that it never happened out of 10 runs
>>>> before, and after that has happened 5 out of 7 times.
>>>>
>>>> Note: On the Tomato Chromebook specifically this USB controller is not connected
>>>> to anything.
>>>>
>>>> [1] 
>>>> https://urldefense.com/v3/__https://linux.kernelci.org/test/case/id/659ce3506673076a8c52a428/__;!!CTRNKA9wMg0ARbw!jtg5drII8WUPwTiL4sWZiSRPXN-EBN8ctTGI85sirqvkmaUbA5z-wrLqPPfxlZZkQ7NItOWDT97OSdENT5oGHKY$
>>>> [2] https://lore.kernel.org/all/239def9b-437b-9211-7844-af4332651df0@mediatek.com/
>>>> [3] 
>>>> https://urldefense.com/v3/__https://linux.kernelci.org/test/case/id/65a8c66ee89acb56ac52a405/__;!!CTRNKA9wMg0ARbw!jtg5drII8WUPwTiL4sWZiSRPXN-EBN8ctTGI85sirqvkmaUbA5z-wrLqPPfxlZZkQ7NItOWDT97OSdENi-d0sVc$
>>>>
>>>> Thanks,
>>>> Nícolas
>>>
>>> Hey Nícolas,
>>>
>>> I wonder if this is happening because of async probe... I have seen those happening
>>> once in a (long) while on MT8186 as well with the same kind of flakiness and I am
>>> not even able to reproduce anymore.
>>>
>>> For MT8195 Tomato, I guess we can simply disable that controller without any side
>>> effects but, at the same time, I'm not sure that this would be the right thing to
>>> do in this case.
>>>
>>> Besides, the controller at 11290000 is the only one that doesn't live behind MTU3,
>>> but I don't know if that can ring any bell....
>>
>> An update on this issue: it looks like it only happens if "xhci-mtk
>> 11290000.usb" probes before "mtk-pcie-gen3 112f8000.pcie". What they have in
>> common is that both of those nodes use phys that share the same t-phy block:
>> pcie uses the usb3 phy while xhci uses the usb2 phy. So it seems that some of
>> the initialization done by the pcie controller might be implicitly needed by the
>> usb controller.
>>
>> This should help to narrow down the issue and find a proper fix for it.
>>
>> Thanks,
>> Nícolas
> 
> 'force-mode' should only applied to the boards which require XHCI function instead 
> of a PCIE port.
> 
> For example, mt8395-genio-1200-evk.dts requires property 'force-mode' to fix probe 
> issue for USBC @11290000.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/mediatek/linux.git/commit/?h=v6.10-next/dts64&id=666e6f39faff05fe12bfc64c64aa9015135ce783
> 
> 'force-mode' should be no need for tomato boards and the behavior should be the 
> same as before.
> 
> Another possibility is the firmware change on tomato boards. I'm not sure if there 
> is any changes on tomato's recent firmware for tphy of this port, which could also 
> be a reason causes this kind of failure.
> I don't have tomato boards on hand.
> 

Hello Macpaul,

it's just about the usb node missing a power domain: as the PCIE_MAC_P1 domain
seems to be shared between USB and PCIe, adding it to the USB node fixes the
setup phase.

I'll send a devicetree fix soon.

Cheers,
Angelo

> Thanks
> Macpaul Lin