On Fri, 16 Jan 2009, Janne Grunau wrote:
> On Friday 16 January 2009 15:39:33 Mike Isely wrote:
> > In any case, right now the serial number in the pvrusb2 is not available
> > through that means because I haven't done anything to make it available
> > to udev. I'd like to do something, but so far I have found no
> > information on how to make that happen.
>
> You shouldn't need to do anything special. The serial number is available
> through the parent USB device. It can be used for udev rules through
> ATTRS{serial} and in sysfs entry of the video device through device/serial.
>
Ah yes!
What I said before was right in its own context, but now I see something
else.
The serial number that the pvrusb2 driver itself knows about is parsed
out of Hauppauge private data by the tveeprom module from the device's
internal I2C ROM. This data is formatted in a packetized way that is
specific to Hauppauge. What I was refering to was *that* serial number,
and since it's in the private ROM I saw no means for udev to know about
it.
However I just tested with two 24xxx devices using usbview, and the same
serial number is in fact visible in the USB configuration data.
There's simply no way for the USB core in Linux to be able to directly
know about, get at, or even understand that internal ROM. Yet there it
is. I'm thinking now that perhaps the FX2 microcontroller is either
parsing out the data itself during initialization and then writing out
the USB configuration accordingly, or the serial number is in fact
written in two places within the device! Up until now, I had not seen
any evidence to suggest that the FX2 firmware ever actually read the
nearby ROM on its own. But that could be what is happening here.
Thanks for pointing that out. These devices still surprise me.
For anyone looking at this, the serial number in the USB configuration
data for the device is just a hex-formatted version of the same value
that you can see via the pvrusb2 driver's sysfs interface.
-Mike
--
Mike Isely
isely @ pobox (dot) com
PGP: 03 54 43 4D 75 E5 CC 92 71 16 01 E2 B5 F5 C1 E8
