linux-kernel - PnP Bios activation of parallel port prior to request

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Date:	Thu, 26 Oct 2006 07:59:21 -0700
From:	Darren Hart <dvhltc@...ibm.com>
To:	lkml <linux-kernel@...r.kernel.org>
Subject: PnP Bios activation of parallel port prior to request_region

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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