Re: [PATCH 1/2] usb: dwc3: dwc3-qcom: Find USB connector and register role switch

[Bryan O'Donoghue <bryan.odonoghue@linaro.org>]

On 29/06/2021 16:48, Bjorn Andersson wrote:
> What's wrong with the switch that dwc3_setup_role_switch() sets up?
> 
> That's what I've been using in my UCSI hacking on Snapdragon 888 and it
> seems to work...
> 
> Regards,
> Bjorn

A good question, which as soon as you asked it made me completely doubt 
if I'd tested the tree without the patch applied.

I reverted both on my working tree and indeed it breaks role-switch 
detection.

In TCPM the connector is a child node of TCPM

https://git.linaro.org/people/bryan.odonoghue/kernel.git/tree/arch/arm64/boot/dts/qcom/qrb5165-rb5.dts?h=usb-next-5.13.rcx-rb5-tcpm 
line 1396

We use a remote endpoint inside of TCPM to hook up into &usb_1 line 1303

Not entirely sure what the graph tree looks like in your USCI case but I 
guess the connector is a child node of the controller ?

But I think your question is why bother with the role-switch in dwc3-qcom

dwc3_qcom_vbus_override_enable(){} is switching bits that probably ought 
to be in the PHY but for whatever reason ended up being buried in the 
qcom-dwc3 wrapper.

Certainly we want that for qcs405 if you remember - I'm assuming for the 
sm8x50 too.

Even if we shouldn't twiddle these bits on sm8x50 I believe its wanted 
on qcs405.

I'm open to correction on that one though

---
bod