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

[Shilimkar, Santosh]

On Thu, Jul 19, 2012 at 3:19 PM, Tero Kristo <t-kristo at ti.com> wrote:
>
> On Thu, 2012-07-19 at 00:55 -0500, Menon, Nishanth wrote:
> > On Wed, Jul 18, 2012 at 4:15 AM, Tero Kristo <t-kristo at ti.com> wrote:
> > >
> > > On Tue, 2012-07-17 at 02:59 -0500, Menon, Nishanth wrote:
> > > > Couple of minor comments:
> > > > On Mon, Jun 11, 2012 at 10:26 AM, Tero Kristo <t-kristo at ti.com>
> > > > wrote:
> > > > [...]
> > > > >  /**
> > > > > + * _omap4_update_context_lost - increment hwmod context loss
> > > > > counter
> > > > > if
> > > > > + * hwmod context was lost, and clear hardware context loss reg
> > > > > + * @oh: hwmod to check for context loss
> > > > > + *
> > > > > + * If the PRCM indicates that the hwmod @oh lost context,
> > > > > increment
> > > > > + * our in-memory context loss counter, and clear the RM_*_CONTEXT
> > > > > + * bits. No return value.
> > > > > + */
> > > > > +static void _omap4_update_context_lost(struct omap_hwmod *oh)
> > > > > +{
> > > > > +       u32 r;
> > > > > +
> > > > > +       if (oh->prcm.omap4.context_offs == USHRT_MAX)
> > > > > +               return;
> > > > would'nt it be better to return a dummy incremental counter instead
> > > > of
> > > > returning no context loss (count = 0)?
> > >
> > > I guess you are right, this way we may have some extra context
> > > restores
> > > for modules which don't have context offs defined, rather than not
> > > restoring them at all. Only thing I can think might prevent this is if
> > > there are modules that never lose context but don't have context
> > > register? How about omap5+?
> >
> > there has been an interesting debate ongoing with HWAUTO and context
> > loss count handling -> since we update only on _enable, this might
> > actually be interesting to consider:
> > enable
> > idle
> > un_idle (lost context)
> > read counter -> no update
> >
> > Now to handle modules that never loose context - they have to be in
> > wakeup domain.. should we consider a flag for those? would'nt matter
> > o5 or not, context is still the same.. this issue could be resolved if
> > counter update is done even when a check is done.
>
> Yea, that would be an option. I think I'll add a flag for not losing
> context ever.
>
You just access the module power domain from hwmod and then
you already know whether it is AON or not. The flag idea
was discussed in context of [1]. See if you can re-use that same idea.

regards
Santosh

[1] https://patchwork.kernel.org/patch/1133491/