[parisc-linux] Re: [parisc-linux-cvs] Diff for PCXS fixes

[John Marvin]

>
> On Wed, Oct 03, 2001 at 02:15:49AM -0600, John Marvin wrote:
> > +     /* Program VIPER to interrupt on the ASP irq */
> > +     gsc_writel((1 << (31 - ASP_GSC_IRQ)),VIPER_INT_WORD);
>
> If we can program Viper (the graphics board, right?) to interrupt on any
> CPU interrupt, why not give it its own rather than make it share an IRQ
> with Asp?

No, that is a misunderstanding. Viper is the memory/bus controller.
Asp is connected to viper, i.e. Asp pulls an interrupt line and viper
writes the interrupt into the cpu eirr. There is not really a hard
wired ASP IRQ as implied in asp.c. the value "3" just happened to
be what was left by the firmware on 720/730. The 710 firmware
leaves a clean slate and unwires the Asp interrupt. This write is
required to let Asp interrupt at all. You can make Asp interrupt on
any irq. I decided to just stick with the 3, but we could change it
or dynamically allocate it.

John