Marvell MV64360 interrupt question

Mark A. Greer mgreer at
Sat Sep 10 07:18:20 EST 2005

On Fri, Sep 09, 2005 at 01:49:55PM -0700, Dale Farnsworth wrote:
> On Fri, Sep 09, 2005 at 08:20:20PM +0000, Walter L. Wimer III wrote:
> > On Fri, 2005-09-09 at 12:27 -0700, Dale Farnsworth wrote:
> > > 
> > > No additional locking is necessary.  In fact, it seems to me that the 32-bit
> > > register reads and writes are already atomic and all of the locking using
> > > mv64x60_lock is superfluous.
> > 
> > Ah ha.  mv64x60.h also defines an mv64x60_modify() function that isn't
> > intrinsically atomic, so it needs the spinlock.  That in turn requires
> > mv64x60_read() and mv64x60_write() to play along too.
> Yes, the lock is needed for mv64x60_modify(), mv64x60_write().  I still
> don't think it's needed for mv64x60_read().

IMHO, the mv64x60_read/write/modify routines should be deleted and the
locking + I/O done explicitly.  That makes it more obvious, more
efficient in places where there are multiple writes, etc. in a row (not
as much grabbing/releasing of the spinlock), and is the preferred way to do
things in linux.

A few times now, I almost started to do that...looked at it and went off
to do something else.  :)  Yes, I'm lazy.  Yes, I should do it.
Eventually, I will (however, if you want to, I won't complain ;).


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