Re: USB Gadget Filesystem HID stuck on write when using mass storage at the same time

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http://daringfireball.net/2007/07/on_top

On Wed, Jun 30, 2021 at 10:55:04AM +0200, Benjamin Marty wrote:

On the iMX8 device `Linux imx8mm-var-dart 5.4.3-g050b21f4b394 #1 SMP
PREEMPT Fri Oct 9 11:36:53 PDT 2020 aarch64 GNU/Linux` and on the
Raspberry Pi device `Linux raspberry 5.10.17-v7l+ #1403 SMP Mon Feb 22
11:33:35 GMT 2021 armv7l GNU/Linux`.

I do not understand, which is the host and which is the gadget here?

File write to `/dev/hidg0` starts to hang when there was high mass
storage traffic. It also doesn't recover itself. There is no `complete
kernel lockup`.

File write on the host or gadget?

If things are not locked up, what is stalled?

I haven't used usbmon yet but if I don't have high traffic scenarios
on the mass storage then the mass storage and HID device works as
expected. So I'm confident that I send the correct data.

That's fine, but it is good to use usbmon to see what the errors are as
well when things go wrong.

Also saw that I'm getting this error in dmesg on both devices:
[ 1895.677053] configfs-gadget gadget: End Point Request ERROR: -108

Ah, is your userspace code on the gadget not handling this properly?
What userspace code is running on the gadget for your USB device
emulation?

thanks,

greg k-h