Re: USB gadget regression on v6.4-rc1 and v6.1.28

[Stephan Gerhold <stephan@gerhold.net>]

On Fri, May 12, 2023 at 11:07:10AM +0200, Francesco Dolcini wrote:
> Hello all,
> I recently did have a regression on v6.4rc1, and it seems that the same
> exact issue is now happening also on v6.1.28.
> 
> I was not able yet to bisect it (yet), but what is happening is that
> libusbgx[1] that we use to configure a USB NCM gadget interface[2][3] just
> hang completely at boot.
> 
> This is happening with multiple ARM32 and ARM64 i.MX SOC (i.MX6, i.MX7,
> i.MX8MM).
> 
> The logs is something like that
> 
> ```
> [*     �F] A start job is running for Load def…t schema g1.schema (6s / no limit)
> M[K[**    �F] A start job is running for Load def…t schema g1.schema (7s / no limit)
> M[K[***   �F] A start job is running for Load def…t schema g1.schema (8s / no limit)
> M[K[ ***  �F] A start job is running for Load def…t schema g1.schema (8s / no limit)
> ```
> 
> I will try to bisect this and provide more useful feedback ASAP, I
> decided to not wait for it and just send this email in case someone has
> some insight on what is going on.
> 

I noticed a similar problem on the Qualcomm MSM8916 SoC (chipidea USB
driver) and reverting commit 0db213ea8eed ("usb: gadget: udc: core:
Invoke usb_gadget_connect only when started") fixes it for me. The
follow-up commit a3afbf5cc887 ("usb: gadget: udc: core: Prevent
redundant calls to pullup") must be reverted first to avoid conflicts.
These two were also backported into 6.1.28.

I didn't have time to investigate it further yet. With these patches it
just hangs forever when setting up the USB gadget.

Stephan