[PATCH 01/16 v3] pmac_zilog: fix unexpected irq

[Benjamin Herrenschmidt]

On Wed, 2011-12-07 at 14:49 +1100, Finn Thain wrote:
> On most 68k Macs the SCC IRQ is an autovector interrupt and cannot be 
> masked. This can be a problem when pmac_zilog starts up.
> 
> For example, the serial debugging code in arch/m68k/kernel/head.S may be 
> used beforehand. It disables the SCC interrupts at the chip but doesn't 
> ack them. Then when a pmac_zilog port is used, the machine locks up with 
> "unexpected interrupt".
> 
> This can happen in pmz_shutdown() since the irq is freed before the 
> channel interrupts are disabled.
> 
> Fix this by clearing interrupt enable bits before the handler is 
> uninstalled. Also move the interrupt control bit flipping into a separate 
> pmz_interrupt_control() routine. Replace all instances of these operations 
> with calls to this routine. Omit the zssync() calls that seem to serve no 
> purpose.
> 
> Signed-off-by: Finn Thain <fthain at telegraphics.com.au>
> Acked-by: Alan Cox <alan at linux.intel.com>
> 
> ---

So basic operations seem to work, I've applied the patch to
powerpc-next.

However, the internal modem on my Pismo powerbook doesn't appear to
survive suspend/resume. I'll dig into that and merge a fixup patch asap.

Cheers,
Ben.