Message-ID: <521df3a8-5bc2-4e81-a819-02b755c88d3a@notapiano>
Date: Thu, 11 Jul 2024 12:33:49 -0400
From: Nícolas F. R. A. Prado <nfraprado@...labora.com>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: Macpaul Lin <macpaul.lin@...iatek.com>,
	Chunfeng Yun <chunfeng.yun@...iatek.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org, kernel@...labora.com,
	Chen-Yu Tsai <wenst@...omium.org>,
	Bear Wang <bear.wang@...iatek.com>,
	Pablo Sun <pablo.sun@...iatek.com>
Subject: Re: Probe failure of usb controller @11290000 on MT8195 after
 next-20231221

On Thu, Jul 11, 2024 at 11:21:14AM +0200, AngeloGioacchino Del Regno wrote:
> 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.

Hi,

As I replied to that patch
(https://lore.kernel.org/all/20240711093230.118534-1-angelogioacchino.delregno@collabora.com)
it didn't fix the issue for me, but I have more updates:

I confirmed the pcie was doing some required setup since disabling the pcie1
node made the issue always happen, and that also made it easier to test.

I was able to track the issue down to the following clock:
<&infracfg_ao CLK_INFRA_AO_PCIE_P1_TL_96M>

Adding it to the clocks property of the xhci1 node fixed the issue.

I'm just not sure from a DT perspective what's the right way to describe this
clock. The node doesn't have the frmcnt_ck, is this that clock? Or is it
another clock that currently isn't described in the dt-bindings and driver?

Thanks,
Nícolas

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