Re: dwc3-qcom: tx-fifo-resize regression on Poco F1 (sdm845) with v5.15-rc1

[Wesley Cheng]

Hi Amit,

On 9/20/2021 1:45 PM, Amit Pundir wrote:
> Hi Wesley, All,
> 
> I see a reboot loop on Xiaomi Pocophone F1 (sdm845) with TX FIFO
> resize patches which landed in v5.15-rc1. Upstream commit cefdd52fa045
> "usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default" to
> be specific, which switched on this feature by default.
> 
> At times the phone crashes into the fastboot mode after the reboot
> loop, but mostly end up booting to UI after a while. This is what it
> looks like https://people.linaro.org/~amit.pundir/beryllium-userdebug/PXL_20210920_162749483.mp4.
> 

I believe Android will attempt a number of bootup sequences and if it
fails, it falls back to fastboot mode.  Are there any available logs you
might be able to collect to see where the issue is?

> PocoF1 does support TX fifo resizing as I can see that in the
> downstream dts. So maybe it is the tx-fifo-max-num which need to be
> adjusted for the device? I couldn't find the tx-fifo-max-num
> equivalent in the downstream tree though
> https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/dipper-q-oss/
> 

I assume that you've already confirmed reverting that change resolves
the constant reboots?

> Curious if you had any ideas what might be going wrong? For now I'll
> keep digging around tx-fifo-max-num, but I figured I'd ask just in
> case it's obvious to you.
> 

The tx-fifo-max-num parameter should still be set to 6 for SDM845, which
would be the same for more recent targets as well.

Thanks
Wesley Cheng

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