[Intel-gfx] [PATCH] drm/i915: Set crtc_state->active to false when CRTC is disabled

[Matt Roper]

With the recent modeset internal rework, we wind up setting crtc_state->enable
to false, but leave crtc_state->active as true following a
drmModeSetCrtc(fb=0), which is incorrect.  This mismatch gets caught by
drm_atomic_crtc_check() and causes subsequent atomic operations (such as plane
updates while the CRTC is disabled) to fail.

Bisect points to

        commit dad9a7d6d96630182fb52aae7c3856e9e7285e13
        Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira at intel.com>
        Date:   Tue Apr 21 17:13:19 2015 +0300

            drm/i915: Use atomic helpers for computing changed flags

as the commit that actually triggers the regression.

Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira at intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Testcase: igt/kms_universal_plane
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
My original expectation was that we'd need to be updating the in-flight CRTC
state rather than the committed state as I wound up doing here.  However it
looks like our legacy modesets aren't yet converted to the point where they do
state swaps, hence the need to update crtc->state directly.

Ander/Maarten, does this look like the right place to have 'active' updated for
the time being, or should it be moved elsewhere in the modeset pipeline?

 drivers/gpu/drm/i915/intel_display.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index c297cdc..be166cf 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6128,6 +6128,8 @@ static void intel_crtc_disable(struct drm_crtc *crtc)
 
 	drm_plane_helper_disable(crtc->primary);
 
+	crtc->state->active = false;
+
 	/* Update computed state. */
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
 		if (!connector->encoder || !connector->encoder->crtc)
-- 
1.8.5.1