[Open-graphics] Video interrupt enable/disable

[Paul Brook]

> > On a typical PCI system each device only gets a single interrupt pin (a
> > PCI bus has 4, but each device is only supposed to use 1), and several
> > devices share an interrupt line.
> >
> > Thus all interrupts should be maskable on the device, and probably
> > combined into a single output after masking.
>
> I'm not a PCI expert.  However, you are talking about the actual
> physical implementation in PCI.  If masking is required, this would be a
> function in the PCI interface.  However, IIUC, PCI devices are allowed
> multiple interrupts -- each PCI device is allowed to use all 4
> interrupts.  If they share common physical interrupt lines, this is an
> issue with the PCI interface hardware and driver.

Each physical card has 4 interrupt pins (usually with a total of 4 shared 
lines per bus), however each logical PCI device is only allowed to use a 
single pin.

IMHO the sync interrupt doesn't need to be different from to any other 
interrupt.

Paul