Re: PureThermal2 UVC video camera: Failed to submit URB 0 (-28)

[Alan Stern <stern@rowland.harvard.edu>]

On Tue, 1 Oct 2019, Tim Harvey wrote:

> On Thu, Sep 26, 2019 at 3:47 PM Tim Harvey <tharvey@gateworks.com> wrote:
> >
> > Greetings,
> >
> > I'm running into an issue with a USB UVC Full speed camera, the
> > PureThermal2 [1] on an IMX6 based ARM board.
> >
> > What I find is that I get two video devices registered (the first one
> > is the expected device, and I'm not clear what the 2nd one is). When I
> > try to capture a single frame I get 'Failed to submit URB 0 (-28)'
> > which historically has been due to a bandwidth issue. I encounter this
> > on the IMX6 EHCI host as well as the OTG host when no other devices
> > are connected (no hubs either). I've tested with both a 4.20 kernel
> > and a 5.3 kernel.
> >
> > If I plug this device into another board I have based on an OcteonTX
> > ARM64 cpu with a fairly modern 4.14 kernel and I find that a single
> > video device gets registered and I can capture just fine.
> >
> > Here are some details:
> > lsusb reports: 1e4e:0100 Cubeternet WebCam
> >
> > working system with 4.14 kernel hot-inserting the camera:
> > [  495.163276] usb 1-1.2: new full-speed USB device number 6 using xhci_hcd
> > [  495.291685] uvcvideo: Found UVC 1.00 device PureThermal (fw:v1.2.2)
> > (1e4e:0100)
> > [  495.300543] input: PureThermal (fw:v1.2.2): PureTh as
> > /devices/platform/soc@0/848000000000.pci/pci0000:00/0000:00:10.0/usb1/1-1/1-1.2/1-1.2:1.0/input/input1
> > [  496.731214] usb 1-1.2: USB disconnect, device number 6
> > [  496.987294] usb 1-1.2: new full-speed USB device number 7 using xhci_hcd
> > [  497.115683] uvcvideo: Found UVC 1.00 device PureThermal (fw:v1.2.2)
> > (1e4e:0100)
> > [  497.124182] input: PureThermal (fw:v1.2.2): PureTh as
> > /devices/platform/soc@0/848000000000.pci/pci0000:00/0000:00:10.0/usb1/1-1/1-1.2/1-1.2:1.0/input/input2

...

> > I'm also not clear why the device enumerates then disconnects and
> > enumerates again when plugged in but this happens on the system it
> > works on as well and I've seen similar things with other devices.

Perhaps some process opens the camera's device file, does something to 
cause the camera to disconnect and reconnect, but then doesn't close 
the file.

> I have found that if I enumerate the camera through a PCIe based XHCI
> host controller it still registers the 2 v4l2 devices but in this case
> I can capture fine. So it would appear that this has something to do
> with the IMX6 ci_hdrc controller. The -ENOSPC is getting returned from
> drivers/usb/host/ehci-sched.c:iso_stream_schedule()
> 
> I feel perhaps this is something basic I don't understand regarding
> USB URB scheduling but I don't get why it occurs on the IMX6 ci_hdrc
> controller on not an XHCI controller.

It's probably related to differences between the drivers.  What shows 
up in /sys/kernel/debug/usb/devices with the camera plugged in?

Alan Stern

> Regards,
> 
> Tim
> 
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