imx8mm/imx8mn hang on usb stop / ehci_shutdown

[Fabio Estevam]

Hi Tim,

On Thu, Apr 27, 2023 at 2:14 PM Tim Harvey <tharvey at gateworks.com> wrote:

> I haven't heard any response here so I did some more digging. This
> hang should be affecting all imx8mm/imx8mn devices that have USB host
> controllers configured for host mode (dr_mode = "host") and would
> appear for anyone that ever does a 'usb stop' (or does a 'usb start'
> followed by a kernel boot for example of loading kernel from USB) in
> U-Boot.

Yes, I recall seeing this issue some time ago but never got a chance
to debug it.

Just tested mainline U-Boot on an imx8mm-evk and there is still a
different issue:

"ums 0 mmc 1" works fine for the first time and it mounts the content
of the SD card correctly on the PC.

After hitting CTRL+C:
CTRL+C - Operation aborted
clk usb_bus already disabled

And after running "ums 0 mmc 1" again, it does not mount the SD card anymore.