Re: DSS2/PM on 3.2 broken?

[Kevin Hilman <khilman@ti.com>]

Tomi Valkeinen <tomi.valkeinen@ti.com> writes:

> On Thu, 2012-01-19 at 11:24 -0800, Kevin Hilman wrote:
>> Tomi Valkeinen <tomi.valkeinen@ti.com> writes:
>
>> > Now, you already said using pm_runtime_put_sync version is the correct
>> > way when suspending. But to use that I need to either always use
>> > pm_runtime_put_sync, or add an extra boolean which marks that we're
>> > suspending, and pass that around, or make it a DSS global variable.
>> 
>> I'm not sure why can't you use the sync version just in the suspend
>> callback?
>
> To do that the suspend callback should be the one that disables the
> device and calls pm_runtime_suspend. With DSS that's not the case, it's
> the panel drivers that are in charge of enabling/disabling DSS (by
> calling appropriate functions in omapdss).

Ah, OK.  makes sense.

> The only thing that the omapdss suspend callback does is to call the
> normal disable functions on the display drivers. This leads to calls to
> disable-functions on the dss hwmod drivers, and then pm_runtime_put
> calls. But at the point the pm_runtime funcs are called, the code has no
> idea that we're actually doing system suspend. Thus I'd need to pass
> that information somehow, probably with a global variable.
>
> And while that's not difficult to do, it sure feels a bit ugly.
>
> I think I'll just change the pm_runtime_put calls to sync versions for
> now. I imagine the perf impact with the change should be negligible.
> I'll return to this issue after the devtree adaptation has been made, as
> it changes the child-parent relations of the dss related devices, and
> perhaps managing the PM states will also get a bit easier.

Sounds reasonable.

Kevin