Ok, so legacy gamma table updates are completely broken for Intel on
Linux-4.7-rc7, the final release candidate.
The good news is that applying Lionel's patch
"drm/i915: add missing condition for committing planes on crtc"
from
https://patchwork.freedesktop.org/patch/89111/
fixes it nicely. The patch currently applies cleanly to drm-fixes and
drm-next and is
Reviewed-and-tested-by: Mario Kleiner <mario.kleiner.de@xxxxxxxxx>
When we are at it, could somebody please look at that updated series of
my Displayport color depth fixes ("EDID/DP fixes for proper bpc
detection of displays.") i sent out a week ago?
Especially pulling patch 2/5 "[PATCH 2/5] drm/i915/dp: Revert
"drm/i915/dp: fall back to 18 bpp when sink capability is unknown" would
be important, as that bug introduced a regression for Intel + DP +
legacy DP converters into stable kernels which is very serious for users
of scientific/medical display equipment, especially as the failures can
easily go unnoticed during normal equipment tests, but would introduce
the equivalent of "silent data corruption" into their measured
scientific data, which is not a great experience given that collecting
such data can easily take half a year of work time and ten-thousands of
euros of wasted research funding.
Patches 3 and 4 contain changes Daniel asked me to do, patch 5 would be
good to safe-guard against similar issues in the future.
thanks,
-mario
On 07/12/2016 12:50 PM, Lionel Landwerlin wrote:
Hi Mario,
There was a couple of patch to fix this issue :
https://patchwork.freedesktop.org/series/5467/
https://patchwork.freedesktop.org/series/5466/
I tested this late last week on drm-intel-nightly, it seems a series of
revert fixed most of the issues.
Cheers,
-
Lionel
On 12/07/16 11:33, Mario Kleiner wrote:
Updating legacy gamma tables, e.g., via RandR doesn't work at all
as of Linux 4.7-rc6.
Reason seems to be that the required call to
drm_atomic_helper_commit_planes_on_crtc is skipped in
intel_atomic_commit after userspace set new gamma tables,
because neither crtc->state->planes_changed nor
update_pipe (= pipe_config->update_pipe) are true.
Removing the check for planes_changed || update_pipe fixes
gamma table updates.
The code for Linux 4.8 drm-next has changed a lot in that area
wrt. 4.7, but the new code for 4.8 also removed those checks
and calls drm_atomic_helper_commit_planes_on_crtc unconditionally,
and legacy gamma lut updates work on drm-next, so this seems to be
the right solution.
Tested also shutdown/reboot, suspend/resume, (un-)plugging displays,
mode switches for resolution/refresh rate, display rotation, and
page-flipping/pageflip timing on Intel HD Ironlake to confirm the
fix apparently doesn't break anything under X11.
Signed-off-by: Mario Kleiner <mario.kleiner.de@xxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
drivers/gpu/drm/i915/intel_display.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
index 04452cf..eb8fb36 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -13685,7 +13685,6 @@ static int intel_atomic_commit(struct
drm_device *dev,
bool modeset = needs_modeset(crtc->state);
struct intel_crtc_state *pipe_config =
to_intel_crtc_state(crtc->state);
- bool update_pipe = !modeset && pipe_config->update_pipe;
if (modeset && crtc->state->active) {
update_scanline_offset(to_intel_crtc(crtc));
@@ -13699,8 +13698,7 @@ static int intel_atomic_commit(struct
drm_device *dev,
drm_atomic_get_existing_plane_state(state, crtc->primary))
intel_fbc_enable(intel_crtc);
- if (crtc->state->active &&
- (crtc->state->planes_changed || update_pipe))
+ if (crtc->state->active)
drm_atomic_helper_commit_planes_on_crtc(old_crtc_state);
if (pipe_config->base.active && needs_vblank_wait(pipe_config))
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