Re: ODROID-C1/-C2 USB Detection only triggered by some devices

From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To: Anand Moon <linux.amoon@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>,
	Minas Harutyunyan <hminas@synopsys.com>,
	 Matt Corallo <oc2udbzfd@mattcorallo.com>,
	 Linux USB Mailing List <linux-usb@vger.kernel.org>,
	linux-amlogic@lists.infradead.org
Subject: Re: ODROID-C1/-C2 USB Detection only triggered by some devices
Date: Fri, 2 Jul 2021 21:33:36 +0200	[thread overview]
Message-ID: <CAFBinCCFhK9Nx9ub5h3JctfXCnbrwL7XPV5dvPXWcvWqupnHkA@mail.gmail.com> (raw)
In-Reply-To: <CANAwSgRPvTyMaQHWFeXcS-r5jdigSbcP0QvaTyJ1GFfUyPpqAg@mail.gmail.com>

Hi Anand,

On Fri, Jul 2, 2021 at 9:12 PM Anand Moon <linux.amoon@gmail.com> wrote:
[...]
> > > I am attaching my usbmon output on Odroid C2.
> > Can you please specifically state the testing steps you have used to
> > obtain that output?
>
> I followed the kernel documentation to get the output
> [0] https://www.kernel.org/doc/html/v5.10/usb/usbmon.html
Alan has previously provided the following command to get the usbmon output:
  cat /sys/kernel/debug/usb/usbmon/0u >mon1.txt

The output of that command depends on various factors:
- which USB devices were plugged in during boot
- which USB devices are plugged in when running "lsusb -vv"
- whether you are using the kernel cmdline option usbcore.autosuspend=-1

For the first two factors the "USB device" can be one of:
- no USB device plugged in at all
- one USB device which is not detected when running "lsusb -vv" (we're
calling this group of devices "first group", an example is my Corsair
Voyager USB 3.0 flash drive)
- one USB device which is being detected when running "lsusb -vv" and
also causing all other devices to be detected (we're calling this
group of devices "second group", an example is a cheap 1GB USB 2.0
flash drive that I have)

As you can see there's lots of combinations possible.
That's why it's important that you mention the exact steps to generate
the usbmon output.

If you're interested you can look at one of my earlier emails [0] (not
sure if you were Cc'ed then) where I was running the cat command as
suggested by Alan three times (each time plugging in different devices
at different times) and got three different outputs.

Best regards,
Martin

[0] https://lore.kernel.org/linux-amlogic/CAFBinCA9Y16Ej3PEBN1Rsqo=6V1AZXKOpTfc_siHP0rvVo7wWQ@mail.gmail.com/

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