Re: [PATCH 1/2] ux500: Adding support for u8500 Hsem functionality V2

[Arnd Bergmann]

On Tuesday 19 April 2011, Mathieu Poirier wrote:
> > One more thing I just noticed: the hwspinlock_internal.h file defines
> > the hwspinlock->id field as "a global, unique, system-wide, index of
> > the lock", but the u8500 hsem just sets it to an integer starting
> > at zero. If there are multiple devices providing hwspinlocks in the
> > same system, that cannot work.
> >
> I have to admit I'm not sure of what your asking here.  Hwspinlocks 
> should be administered by only one entity and this is what this driver 
> is doing.
> 
> Please get back to me with a clarification.

You could have a system with multiple instances of the hardware block
that holds your spinlock. I've seen SMP systems that basically take
multiple SOCs and put them into a common address space.

More importantly, there could be a device on an external bus that also
provides a hwspinlock. The API can deal with this, but your driver will
conflict with any other driver trying to do the same.

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/