AW: [Linux-parport] ECR Register in PCI based ECP port

Ravi Shah shahravi20 at
Sun Mar 7 12:23:00 GMT 2004

Do I need to do anything before I can start seeing the parallel port registers (ECP), ie
do I need to set any bits?


--- Michael Kastner <michael.kastner at> wrote:
> > But somehow I am not able to locate the ECR register the 
> > memory space (where my PCI card is mapped) 
> > 
> > I tried reading the default values from these locations, and 
> > it all returns zeroes (which is not correct, it should be 
> > 0x01. Then I tried writing 0x34 at the ECR (guessed) 
> > location, it still does not work.
> > 
> > Any ideas whats wrong here. Do I need to do anything after 
> > connecting the PCI cards such that my registers become visible.
> Hello Ravi!
> You can determine the base addresses by typing
> cat /proc/pci
> in a shell. This will give you a listing of all installed PCI devices.
> Among them you will find the parallel port card.
> It should look something like this.
>   ...
>   Bus  0, device   9, function  0:
>     Communication controller: PCI device 9710:9805 (NetMos Technology) (rev
> 1).
>       IRQ 9.
>       Master Capable.  Latency=32.  
>       I/O at 0xd000 [0xd007].
>       I/O at 0xb800 [0xb807].
>       I/O at 0xb400 [0xb407].
>       I/O at 0xb000 [0xb007].
>       I/O at 0xa800 [0xa807].
>       I/O at 0xa400 [0xa40f].
>   ...
> The first I/O address (0xd000 in this case) is the base address for the
> standard parallel port registers (like 0x378 for LPT1) and the second one
> (0xb800) is the base address for the ECP registers (like 0x778 for LPT1).
> The ECR register here is at address 0xb802.
> However it seems like these should be the same addresses as returned by
> pciHeaderShow(0,0,0).
> Regards,
>   Michael

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