[Libdlo] Problem with reading EDID from monitor that should work

[Bernie Thompson]

Hi Alexander,

On Tue, Sep 14, 2010 at 1:43 PM, Alexander Todorov <atodorov at otb.bg> wrote:
> Hi all,
> I've decided to upgrade the configuration that I use and gave a try of the new
> sources (not latest git).
>
> When the driver loads I get an error message:
> dlfb: Unrecognized vendor firmware descriptor

The vendor descriptor is part of the USB descriptors coming directly
from the USB device (the DispayLink device's firmware).  So you should
see the "dlfb: Unrecognized vendor firmware descriptor" (or lack of
it), regardless of what monitor is attached.

All recent DisplayLink devices have this extra area of the USB
descriptors, and it's the only place where we can get reliable
information about what the particular DisplayLink chip's mode limits
are.  So the unrecognized firmware descriptor warning should be rare,
and only with older devices.

I know you have some Plugable docking stations - is this vendor
firmware warning on one of them, or another DisplayLink device?

Because there are early DisplayLink devices without vendor firmware,
udlfb will continue on even if there is an unrecognized firmware
descriptor - and will assume the highest possible max mode for the
chip (2048x1152).

So that message in kern.log is a warning, but udlfb will go on.  To
see what's happening when you don't get a green screen, we'd have to
see what's in the rest of the kern.log after the warning.  Can you
post that?

And can you also post "uname -a" for kernel version and arch?

Best wishes and thanks!
Bernie