On Tue, Apr 1, 2014 at 9:46 PM, Dave Airlie airlied@gmail.com wrote:
On Tue, Apr 1, 2014 at 5:45 PM, Daniel Vetter daniel@ffwll.ch wrote:
commit a3a0544b2c84e1d7a2022b558ecf66d8c6a8dd93 Author: Dave Airlie airlied@redhat.com Date: Mon Aug 31 15:16:30 2009 +1000
drm/kms: add explicit encoder disable function and detach harder. For shared tv-out and VGA encoders, we really need to know if the encoder is just being switched off temporarily in blanking or if we are really disabling it hard. Also we need to try harder to disconnect encoders from unused connectors so we can share more efficently. (shared encoders stuff is coming in radeon tv-out support) Signed-off-by: Dave Airlie <airlied@redhat.com>To me this always smelled like papering over broken userspace. I've killed this in the i915 modeset rewrite and we didn't really have angry users scaling our walls. But I'm not sure what'll happen if we do this for all other drivers.
I've had to look at this again recently, and while I still don't like my commit, its not papering over userspace, it might be papering over fbcon :-)
You don't have any hw that operates like this, so I'd be surprised if you had users falling over,
The problem is if I have a single DAC encoder, with tv-out and VGA connectors, and I unplug the VGA connector, and plug in the tv connector, how do I get fbcon to pop-up,
Though that said this commit caused a regression that I'm not sure I liked either, since I think we used to allow you to force a mode on disconnected outputs, and this stops that from working, I noticed in a virtual env.
As discussed on irc I think we should be able to fix the issue with fbcon by using an atomic modeset. The bug only happens when fbcon tries to enable the newly plugged-in connector before it disabled the old one and then can't get at the shared encoder needed to enable either. If we have atomic modesets the crtc helpers can always first disable all the unused stuff and then light up the new things, which should make this work. So imo disabling this hunk as in the patch I've just sent out looks like the way forward for primary planes and atomic modeset. -Daniel