[linux-uvc-devel] questions about noname china usb camera

[treaki]

Hi,

for the purpose of building a security rPi System i bought 5 noname
china cameras from amazon. You can access the (german) product
description at:
http://www.amazon.de/gp/product/B00C5W2UDG

One of them alone is working without problems with the uvcvideo driver.
But if you connect more then one you will get funny errors in dmesg:
[455874.477242] uvcvideo: Failed to submit URB 0 (-28).

if you try to open more then one /dev/videoX device at once. Also i have
got now 4 /dev/videoX devices even true i have only connected 2 cameras
and no program is accessing them.

I guess that is not a question about the driver, more its a question
about the firmware implementation of the usb cams. I looked at the
lsusb -v output and compared both cameras with one also working philips
usb cam:

http://treaki.tk/upload/uploads/1390495039/140123_usb_camara_amazon_rezension.zip

So i have got following questions which i hope to get answered from you:

1. Am i right with my supposement that an serial numer is needed at a
correct implemented usb device?

2. Is it a good idea to add this camara to the compatibility list?

3. Is there a way to make the driver work even true the used camaras are
bad implemented


Many thanks in advance for the help,

greetings
treaki

[treaki]

Hi,

for the purpose of building a security rPi System i bought 5 noname
china cameras from amazon. You can access the (german) product
description at:
http://www.amazon.de/gp/product/B00C5W2UDG

One of them alone is working without problems with the uvcvideo driver.
But if you connect more then one you will get funny errors in dmesg:
[455874.477242] uvcvideo: Failed to submit URB 0 (-28).

if you try to open more then one /dev/videoX device at once. Also i have
got now 4 /dev/videoX devices even true i have only connected 2 cameras
and no program is accessing them.

I guess that is not a question about the driver, more its a question
about the firmware implementation of the usb cams. I looked at the lsusb
-v output and compared both cameras with one also working philips usb cam:

http://treaki.tk/upload/uploads/1390495039/140123_usb_camara_amazon_rezension.zip

So i have got following questions which i hope to get answered from you:

1. Am i right with my supposement that an serial numer is needed at a
correct implemented usb device?

2. Is it a good idea to add this camara to the compatibility list?

3. Is there a way to make the driver work even true the used camaras are
bad implemented


Many thanks in advance for the help,

greetings
treaki

[Paulo Assis]

Hi,

Post by treaki
Hi,
for the purpose of building a security rPi System i bought 5 noname
china cameras from amazon. You can access the (german) product
http://www.amazon.de/gp/product/B00C5W2UDG
One of them alone is working without problems with the uvcvideo driver.
[455874.477242] uvcvideo: Failed to submit URB 0 (-28).

This is a usb bandwith issue, basically the usb bandwith requested by
the device doesn't allow for the connection of the second camera..
In a PC you just need to connect the cameras to different usb
controllers, in the rPi i'm not sure how to solve this.

Post by treaki
if you try to open more then one /dev/videoX device at once. Also i have
got now 4 /dev/videoX devices even true i have only connected 2 cameras
and no program is accessing them.

For every camera that you connect you will get a /dev/videoN node, the
nodes may not be being removed properly, this can happen if the camera
crashes (maybe caused by the bandwith issue).
You can try to fix this with:

rmmod uvcvideo && modprobe uvcvideo

Regards,
Paulo

Post by treaki
I guess that is not a question about the driver, more its a question
about the firmware implementation of the usb cams. I looked at the
lsusb -v output and compared both cameras with one also working philips
http://treaki.tk/upload/uploads/1390495039/140123_usb_camara_amazon_rezension.zip
1. Am i right with my supposement that an serial numer is needed at a
correct implemented usb device?
2. Is it a good idea to add this camara to the compatibility list?
3. Is there a way to make the driver work even true the used camaras are
bad implemented
Many thanks in advance for the help,
greetings
treaki
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