PnP Bios activation of parallel port prior to request_region

From: Darren Hart
Date: Thu Oct 26 2006 - 11:12:40 EST


While working with a very simple demo parallel port interrupt driver, I found
that request_region() will successfully return, regardless of whether or not
the pnp calls have been made to activite the parallel port on a pnp system.

The driver worked by just calling request_region() on another system, but on
my laptop it wouldn't work unless I made the pnp activation calls before
hand. The confusion came because the io range got assigned to my module,
showed up in /proc/ioports, etc. So it appeared to be properly configured,
but all the inb() calls returned 0xff.

I know have something working, but just wanted to ask if it is considered
correct behavior for request_region() to succeed on an io range pertaining to
a device that needs to be initialized by the pnp system and hasn't been.


--
Darren Hart
IBM Linux Technology Center
Realtime Linux Team
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