[alsa-devel] Fwd: [PATCH] Dreamcast AICA sound driver G2 bus handling

[Adrian McMenamin]

On 17/09/2007, Takashi Iwai <tiwai at suse.de> wrote:
> At Sun, 16 Sep 2007 12:12:08 +0100,
> Adrian McMenamin wrote:
> >
> > Resending this as I typed the wrong address for alsa-devel last night.
> > A general clean up as well as some changes to interrupt handling.
> >
> >
> >
> > This patch handles instability on the Dreamcast G2 bus while PIO or
> > DMA is underway on the System -> AICA channel.
> >
> > Without the suspension of interrupts when PIO or DMA is underway the
> > G2 bus is prone to timeouts leading to seemingly random crashes. This
> > is particularly visible in cases such as maple bus (see
> > http://lkml.org/lkml/2007/9/15/181) hotplugging but the patch is good
> > for all conditions.
>
> Hm, it isn't optimal but if it's safe...
>
> BTW, what is the exat matter?
> Is it race or do you have to always disable IRQ during DMA?
> In the former case, spin_lock_irqsave() is basically the way to go.
>

I'm afraid it is a hardware bug/feature rather than a race. I'll
rework and repost