Re: [PATCH 09/81] drm/i915/lvds: ditch ->prepare special case

Takashi Iwai
2012-07-22T16:32:11Z

At Sun, 22 Jul 2012 16:52:54 +0200,
Daniel Vetter wrote:
>
> On Wed, Jul 11, 2012 at 04:27:52PM +0200, Daniel Vetter wrote:
> > LVDS is the first output where dpms on/off and prepare/commit don't
> > perfectly match. Now the idea behind this special case seems to be
> > that for simple resolution changes on the LVDS we don't need to stop
> > the pipe, because (at least on newer chips) we can adjust the panel
> > fitter on the fly.
> >
> > There are a few problems with the current code though:
> > - We still stop and restart the pipe unconditionally, because the crtc
> > helper code isn't flexible enough.
> > - We show some ugly flickering, especially when changing crtcs (this
> > the crtc helper would actually take into account, but we don't
> > implement the encoder->get_crtc callback required to make this work
> > properly).
> >
> > So it doesn't even work as advertised. I agree that it would be nice
> > to do resolution changes on LVDS (and also eDP) whithout blacking the
> > screen where the panel fitter allows to do that. But imo we should
> > implement this as a special case a few layers up in the mode set code,
> > akin to how we already detect simple framebuffer changes (and only
> > update the required registers with ->mode_set_base).
> >
> > Until this is all in place, make our lives easier and just rip it out.
> >
> > Also note that this seems to fix actual bugs with enabling the lvds
> > output, see:
> >
> > http://lists.freedesktop.org/archives/intel-gfx/2012-July/018614.html
> >
> > Cc: Takashi Iwai <tiwai@suse.de>
> > Cc: Giacomo Comes <comes@naic.edu>
> > Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>
> I've merged this with Chris' irc-ack (under the condition that the
> modeset-rework leads to reinstated lvds fastpath that actually works
> eventually). I've stalled a bit for tested-bys from Takashi, but he seems
> to be awol atm.

Sorry, I was too busy for other tasks after vacation.
Tested on a few machines and it worked as expected.

Tested-by: Takashi Iwai <tiwai@suse.de>

Takashi