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

[Ravi Shah]

Thanks Michael!

I am trying to locate ECR at baseaddress_1 + 0x2 (as pointed out by you). 

Just to make sure, to detect the existence of ECR, the default value at that location
should be 0x01, and on writing 0x34 to it, it shall return 0x35 (since the last two bits
are read only).

Please confirm if I am right,

Thanks,
Ravi

--- Michael Kastner <michael.kastner at gmx.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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