[PATCHv6 4/7] ARM: OMAP: hwmod: Add support for per hwmod/module context lost count

[Tero Kristo]

On Thu, 2012-07-19 at 05:27 -0500, Menon, Nishanth wrote:
> On Thu, Jul 19, 2012 at 4:49 AM, Tero Kristo <t-kristo at ti.com> wrote:
> >
> > Zero doesn't mean no context loss. If counter was previous MAX_INT, if
> > it goes to zero it is still a context loss, as the counter value
> > differs. Drivers do check against diff in the context loss counter, and
> > if there is one, they do restore which is the right way to handle it. No
> > need to unnecessarily make this more complicated than it is.
> 
> so we flip the responsibility of overflow to drivers. considering a
> similar scenario of jiffies
> /*
>  *      These inlines deal with timer wrapping correctly. You are
>  *      strongly encouraged to use them
>  *      1. Because people otherwise forget
>  *      2. Because if the timer wrap changes in future you won't have to
>  *         alter your driver code.
>  *
>  * time_after(a,b) returns true if the time a is after time b.
> ...
> */
> from past experience, it is highly possible that drivers never get
> this right. if the intent is just to let the drivers know context was
> lost, why not go back to the alternate possibility of a bool
> lost_context which tells the driver if it lost context since it last
> called the lost_context api.

This goes to the discussion whether the API of lost context stuff is
correct or not, and goes out of scope for this set.

I am just attempting to bring omap4 to omap3 level in the first place,
we can discuss about the potential API problems separately, and a change
like that should be relatively easy to implement anyway.... but will
break several drivers.

-Tero