Re: [PATCH] qe_ic: Do a sync when masking interrupts.

On Oct 23, 2006, at 10:19 AM, Scott Wood wrote:

Paul Mackerras wrote:

quoted

Hmmm.  In general a sync having completed doesn't mean that previous
MMIO stores have actually got to the device.  Reading from a device
register generally does ensure that previous writes have actually got
to the device though - could you do that instead?  I'm concerned that
adding the sync is not a robust fix and is possibly only working due
to fortuitous timing.

Possibly -- but the only problem on the rare occasions where the  
timing
is not fortuitous is a spurious interrupt; the only reason the sync
needs to be there at all is to avoid the overhead of the extra  
interrupt
(and to avoid user complaints that they're getting "BAD" interrupts).

Why wouldn't the read accomplish the same thing in a more robust way  
than the sync?

- k