PnP Bios activation of parallel port prior to request_region

PnP Bios activation of parallel port prior to request_region

[Darren Hart]

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

Re: PnP Bios activation of parallel port prior to request_region

[Oleg Verych]

On 2006-10-26, Darren Hart <dvhltc@us.ibm.com> wrote:
> 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 
"now"?
> 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.

I know that legacy parallel port must work regadless of any parport
modules, using /dev/port and BIOS setup for EPP/ECP etc.

If you really want to be answered, try to address message (or cc) to
e-mails mentioned in
- `linux/MAINTAINERS.*PARALLEL PORT*'
- `linux/drivers/parport/parport_pc.c'
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