[PATCH 1/3] drm: Send pending vblank events before disabling vblank.
Christopher James Halse Rogers
christopher.halse.rogers at canonical.com
Wed Apr 27 02:17:42 PDT 2011
On Wed, 2011-04-27 at 11:08 +0200, Michel Dänzer wrote:
> On Mit, 2011-04-27 at 18:58 +1000, Christopher James Halse Rogers
> > On Wed, 2011-04-27 at 10:32 +0200, Michel Dänzer wrote:
> > > On Mit, 2011-04-27 at 16:10 +1000, christopher.halse.rogers at canonical.com wrote:
> > > > From: Christopher James Halse Rogers <christopher.halse.rogers at canonical.com>
> > > >
> > > > This is the least-bad behaviour. It means that we signal the
> > > > vblank event before it actually happens, but since we're disabling
> > > > vblanks there's no guarantee that it will *ever* happen otherwise.
> > >
> > > This may indeed be the best we can do for events that are pending when
> > > the CRTC is disabled, but I can't see anything that would prevent new
> > > events from getting scheduled (or synchronous vblank waits from timing
> > > out) while the CRTC is disabled?
> > >
> > >  Though it might unnecessarily send events prematurely when the CRTC
> > > is just disabled temporarily, e.g. as part of a modeset.
> > >
> > >
> > > Also, this patch won't seem to help at all for other drivers which don't
> > > call drm_vblank_off() directly when disabling a CRTC.
> > This is true. On the other hand, the other drivers don't wedge the
> > vblank code into a state where vblanks cannot be re-enabled. So it's
> > only a problem when disabling one of 2+ monitors on those drivers,
> And with DPMS?
Possibly. Since vblanks aren't wedged off in this case it's more likely
that the user turning the monitors back on will result in a vblank irq,
which will kick everything back into correct operation.
I've not managed to trigger this on my radeon system in the same way as
my intel systems, but I haven't stressed it as hard either.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Size: 490 bytes
Desc: This is a digitally signed message part
More information about the dri-devel