Atm the crtc helper implementation of set_config has really
inconsisten semantics: If just an fb update is good enough, dpms state
will be left as-is, but if we do a full modeset we force everything to
dpms on.
This change has already been applied to the i915 modeset code in
commit e3de42b684
Author: Imre Deak <imre.deak@intel.com>
Date: Fri May 3 19:44:07 2013 +0200
drm/i915: force full modeset if the connector is in DPMS OFF mode
which according to Greg KH seems to aim for a new record in most
Bugzilla: links in a commit message.
The history of this dpms forcing is pretty interesting. This patch
here is an almost-revert of
commit 811aaa55ba
Author: Keith Packard <keithp@keithp.com>
Date: Thu Feb 3 16:57:28 2011 -0800
drm: Only set DPMS ON when actually configuring a mode
which fixed the bug of trying to dpms on disabled outputs, but
introduced the new discrepancy between an fb update only and full
modesets. The actual introduction of this goes back to
commit bf9dc102e2
Author: Keith Packard <keithp@keithp.com>
Date: Fri Nov 26 10:45:58 2010 -0800
drm: Set connector DPMS status to ON in drm_crtc_helper_set_config
And if you'd dig around in the i915 driver code there's even more fun
around forcing dpms on and losing our heads and temper of the
resulting inconsistencies. Especially the DP re-training code had tons
of funny stuff in it.
v2: So v1 totally blew up on resume on my radeon system here. After
much head-scraching I've figured out that the radeon resume functions
resumes the console system _before_ it actually restores all the
modeset state. And resuming the console systems means that fbdev doeas
an immediate ->set_par call.
Now up to this patch that ->set_par did absolutely nothing: All the
old sw state from pre-suspend was still around (since the modeset
reset wasn't done yet), which means that the set_config calls done as
a result of the ->set_par where all treated as no-ops (despite that
the real hw state was obviously something completely different).
Since v1 of this patch just added a bunch of ->dpms calls if the crtc
was enabled, those set_config calls suddenly stopped being no-ops. But
because the hw state wasn't restored the ->dpms callbacks resulted in
decent amounts of hilarity and eventual full hangs.
Since I can't review all kms drivers for such tricky ordering
constraints v2 opts for a different approach and forces a full modeset
if the connector dpms state isnt' DPMS_ON. Since the ->dpms callbacks
implemented by the modeset helpers update the connector->dpms property
we have the same effect of ensuring that the pipe is ultimately turned
on, even if we just end up updating the fb. This is the same approac
we ended up using in the intel driver.
Note that besides i915.ko only all other drivers eventually call
drm_helper_connector_dpms with the exception of vmwgfx, which does not
support dmps at all.
v3: Dave Airlie merged the broken first version of this patch, so
squash in the revert of
commit 372835a852
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Sat Jun 15 00:13:13 2013 +0200
drm/crtc-helper: explicit DPMS on after modeset
Also fix up the spelling fail a bit in the commit message while at it.
Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67043
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
25f397a429