Re: [PATCH] Patch pvr2 driver to allow development of maple bus driver

[Mike F. <va...@ge...>]

On Friday 31 August 2007, Adrian McMenamin wrote:
> On 31/08/2007, Mike Frysinger <vap...@gm...> wrote:
> > On 8/31/07, Adrian McMenamin <lkm...@gm...> wrote:
> > > This patch makes the PVR2 VBLANK interrupt on the SEGA Dreamcast
> > > shareable - a small but necessary change to enable ongoing efforts to
> > > develop a driver for the maple bus on the Dreamcast. (Maple is Sega's
> > > proprietary serial interface for the Dreamcast and can be set to
> > > synchronise dma transfers to the VBLANK).
> > >
> > > This has no impact on the performance of the PVR2.
> >
> > sharable implies the interrupt handler checks to see if it actually
> > caused the interrupt ... which it doesnt at the moment ... presumably,
> > you're making it shared because another device will be using that
> > interrupt as well ... so when that other device gets an interrupt, how
> > do you know it's for that device and not PVR2 ?
>
> If the interrupt occurs then it will be for both of them. The hardware
> cannot be removed and the maple bus driver is set for hardware sync.
>
> The question seems redundant to me.

i really dont know how the maple bus works or what piece of hardware is wir=
ed=20
up to the same interrupt line.  my point is that if the other device fires =
an=20
interrupt, the pvr interrupt handler may be executed and attempt to do work=
=20
when in reality the pvr was not the source of the interrupt.
=2Dmike