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SubjectRe: [PATCH 04/11] ST SPEAr: Added basic header files for SPEAr platform
On Wed, 10 Mar 2010, Paul Mundt wrote:
> On Wed, Mar 10, 2010 at 03:41:51PM +0530, Viresh KUMAR wrote:
> > As you may have seen in spear.h files in mach folders, we have multiple hardware
> > timers in our design (3 in spear3xx, 4 in spear6xx and each timer have two
> > independent channels. That doubles the timers count, so it is 6 and 8).
> > One timer (or two channels) are used by clock event and clock source, but rest of
> > the timers are still available. So we need some way to export this functionality
> > of our hardware. It can be considered simply as a driver for GPT.
> >
> > What do you say?
> >
> This is hardly a unique situation for your platform, this is true for
> most platforms. There's no reason why clockevents couldn't just be
> extended and drivers could then just grab unused clockevents and pin them
> accordingly. Most of the infrastructure is already in place for something
> like that, without really having to do anything special.
> Having said that, most drivers have pretty lame reasons for trying to get
> at fixed timer channels, and most of the time they can easily get by with
> an hrtimer instead. There's also the issue that you're effectively
> bypassing nohz by having some timer channel off on the side doing who
> knows what. You would need a pretty compelling reason for why you are
> sidestepping all of the existing infrastructure anyways.

Right, and that's exactly the reason why we did not add the few
missing bits to make clock events directly usable from drivers.



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