Re: updating usb and pci id lists

From: Dazed_75 <lthielster@gmail.com>
> Can anyone give a brief description of how the system knows what driver
> to use for a given device?

USB devices all have a vendor ID and product ID (16-bit numbers) that they can
report via some standardized commands. IIRC, when a USB module sees a new USB
device that has the right vendor and product ID for it on the bus, that module
claims that device, and then does whatever that device needs (initialization,
quirk detection, whatever). Then the higher-level subsystems like v4l or
storage make that device available via block or char device files. If you
have a helpful distro like Ubuntu, there might be udev rules that
automatically modprobe the right modules when they see a vendor/product of
1234:abcd show up on the bus.

All of this is controlled by the kernel code under /usr/src/linux/ , not by
any userspace files that lsusb uses. Unless you've got one of those devices
that uses libusb, which is possible, like with some scanners.

> 3) If the generic answer is too complicated, how about specifically for a
> webcam or a 3G modem?

Webcams made in the last 2-3 years should all follow the USB Device Class
"video" standards, and should all be supported by the uvcvideo module. You
should check to make sure that module exists, and if it doesn't, you need to
upgrade to the latest kernel you can get.

No idea about 3G modems, since I've never used one.

--
Matt G / Dances With Crows
The Crow202 Blog: http://crow202.org/wordpress/
There is no Darkness in Eternity/But only Light too dim for us to see


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