Re: DSS2/PM on 3.2 broken?

[NeilBrown <neilb@suse.de>]

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On Wed, 18 Jan 2012 09:13:59 +0200 Tomi Valkeinen <tomi.valkeinen@ti.com>
wrote:

> On Fri, 2012-01-13 at 22:20 +1100, NeilBrown wrote:
> > Having CPUIDLE makes the DSS2 problem worse: lots of 
> > 
> > [   21.085113] omapdss DISPC error: SYNC_LOST on channel lcd,
> > restarting the output with video overlays disabled
> > 
> > messages whenever the CPU isn't busy.
> 
> I'm not sure if it is the case here, but DSS has restrictions about the
> max DSS clocks on different OPPs. For example, on OMAP4430 LCD clock
> maximum is 186MHz at OPP100, and 93MHz at OPP50. So it's a quite big
> drop, causing problems with all but the rather small displays.
> 
> And the DSS driver doesn't have any support to handle this at the
> moment, as there isn't support in the PM framework to do this. I think
> the only way to handle this at the moment is for the DSS driver to set
> an arbitrarily high constraint on, say, mem throughput, and hope that it
> keeps the OMAP in the required OPP.
> 
>  Tomi
> 

This LCD panel on this device sets:
   .pixel_clock	= 22000,
in the "struct omap_video_timings" so I'm guessing that is 22MHz?

I'll try building without SMARTREFLEX and see if that makes a difference -
presumably that should keep it at OPP100 (??).

Thanks,
NeilBrown

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