[sane-devel] Canon on Raspberry Pi

[Sean Greenslade]

On Mon, May 18, 2020 at 08:18:36PM +0200, Mac Goever wrote:
> Hi Sean,
> 
> yes, I can do that. Here are some log entries. I suspected the device
> to disappear right after the "reset" entry. But this is not the case.
> It might also disappear some seconds after the event.
> 
> ---
> [  328.405481] usb 1-1.4: new high-speed USB device number 5 using dwc_otg
> [  328.537196] usb 1-1.4: New USB device found, idVendor=05e3,
> idProduct=0605, bcdDevice= 6.0b
> [  328.537212] usb 1-1.4: New USB device strings: Mfr=0, Product=1,
> SerialNumber=0
> [  328.537221] usb 1-1.4: Product: USB2.0 Hub
> [  328.538152] hub 1-1.4:1.0: USB hub found
> [  328.538449] hub 1-1.4:1.0: 4 ports detected
> [  328.675475] usb 1-1.2: reset high-speed USB device number 4 using dwc_otg
> [  334.252684] usb 1-1.2: USB disconnect, device number 4
> [  338.085480] usb 1-1.4.3: new high-speed USB device number 6 using dwc_otg
> [  338.216965] usb 1-1.4.3: New USB device found, idVendor=04a9,
> idProduct=190e, bcdDevice= 7.04
> [  338.216981] usb 1-1.4.3: New USB device strings: Mfr=1, Product=2,
> SerialNumber=0
> [  338.216991] usb 1-1.4.3: Product: CanoScan
> [  338.217000] usb 1-1.4.3: Manufacturer: Canon

Up to here, this is a normal USB enumeration.

> [  348.615487] usb 1-1.4.3: reset high-speed USB device number 6 using dwc_otg

But here, 10 seconds after enumerating, we see an unexpected reset.

> [  781.257336] usb 1-1.4.3: USB disconnect, device number 6

And ~7 minutes later, the device disconnects.

> [  787.105074] usb 1-1.4.3: new high-speed USB device number 7 using dwc_otg
> [  787.236590] usb 1-1.4.3: New USB device found, idVendor=04a9,
> idProduct=190e, bcdDevice= 7.04
> [  787.236620] usb 1-1.4.3: New USB device strings: Mfr=1, Product=2,
> SerialNumber=0
> [  787.236630] usb 1-1.4.3: Product: CanoScan
> [  787.236639] usb 1-1.4.3: Manufacturer: Canon

Another normal enumeration.

> [  791.095083] usb 1-1.4.3: reset high-speed USB device number 7 using dwc_otg

And another unexpected reset after a few seconds.

> [  981.232218] usb 1-1.4.3: USB disconnect, device number 7

This time, the disconnect happened in ~3 minutes.

> [  991.254819] usb 1-1.4.3: new high-speed USB device number 8 using dwc_otg
> [  991.386331] usb 1-1.4.3: New USB device found, idVendor=04a9,
> idProduct=190e, bcdDevice= 7.04
> [  991.386348] usb 1-1.4.3: New USB device strings: Mfr=1, Product=2,
> SerialNumber=0
> [  991.386358] usb 1-1.4.3: Product: CanoScan
> [  991.386367] usb 1-1.4.3: Manufacturer: Canon
> [ 2101.778329] usb 1-1.4.3: USB disconnect, device number 8
> [ 2279.596695] usb 1-1.4: USB disconnect, device number 5
> [78022.354395] usb 1-1.2: new high-speed USB device number 9 using dwc_otg
> [78022.486136] usb 1-1.2: New USB device found, idVendor=05e3,
> idProduct=0605, bcdDevice= 6.0b
> [78022.486152] usb 1-1.2: New USB device strings: Mfr=0, Product=1,
> SerialNumber=0
> [78022.486161] usb 1-1.2: Product: USB2.0 Hub
> [78022.487104] hub 1-1.2:1.0: USB hub found
> [78022.487402] hub 1-1.2:1.0: 4 ports detected

A USB hub was plugged in. Notice that this device doesn't ever have a
reset, so it's behaving correctly.

> [78022.804366] usb 1-1.2.3: new high-speed USB device number 10 using dwc_otg
> [78022.935681] usb 1-1.2.3: New USB device found, idVendor=04a9,
> idProduct=190e, bcdDevice= 7.04
> [78022.935690] usb 1-1.2.3: New USB device strings: Mfr=1, Product=2,
> SerialNumber=0
> [78022.935695] usb 1-1.2.3: Product: CanoScan
> [78022.935699] usb 1-1.2.3: Manufacturer: Canon

The scanner was plugged in, presumably into the hub.

> [78032.084421] usb 1-1.2.3: reset high-speed USB device number 10 using dwc_otg

And our friend the reset is back.

In short, the issue is almost certainly in hardware.

My prime suspects would be:
- Insufficient power supply stability. This refers to both current
  capacity and voltage sag, the latter of which can be hard to test.
  Additionally, a real 10 A 5 V power supply should be fairly large,
  comparable to a medium-size laptop brick. If your 10 A supply is a
  wall wart, I would be very suspicious of it.

  If you have a good multimeter, I would suggest measuring the 5 V rail
  on the Pi's GPIO headers while you have the scanner plugged in.
  Anything below 4.9 V would be concerning.

- Flaky USB cable. Try another one if you have it, the shorter the
  better.

- Flaky USB port. Try the other ports on the Pi just to see.

- Flaky powered USB hub / poor quality hub power supply. Cheap hubs
  often have equally cheap power supplies.

- Damaged USB subsystem on Pi. This one is unlikely, but it may be worth
  testing other USB devices (e.g. a thumb drive) on your Pi and see if
  you get similar issues.

Hopefully this helps narrow down the issue.

--Sean