[PATCH 33/81] drm/i915: WARN when trying to enabled an unused crtc

Daniel Vetter
2012-07-11T15:35:52Z

This is the first tiny step towards cross-checking the entire modeset
state machine with WARNs. A crtc can only be enabled when it's
actually in use, i.e. crtc->active imlies crtc->enabled.

Unfortunately we can't (yet) check this when disabling the crtc,
because the crtc helpers are a bit slopy with updating state and
unconditionally update crtc->enabled before changing the hw state.

Fixing that requires quite some more work.

Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/gpu/drm/i915/intel_display.c | 4 ++++
drivers/gpu/drm/i915/intel_drv.h | 10 +++++++++-
2 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index b91e7ea..744241e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3184,6 +3184,8 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
u32 temp;
bool is_pch_port;

+ WARN_ON(!crtc->enabled);
+
/* XXX: For compatability with the crtc helper code, call the encoder's
* enable function unconditionally for now. */
if (intel_crtc->active)
@@ -3379,6 +3381,8 @@ static void i9xx_crtc_enable(struct drm_crtc *crtc)
int pipe = intel_crtc->pipe;
int plane = intel_crtc->plane;

+ WARN_ON(!crtc->enabled);
+
/* XXX: For compatability with the crtc helper code, call the encoder's
* enable function unconditionally for now. */
if (intel_crtc->active)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 02aea23..c5b71bf 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -156,7 +156,15 @@ struct intel_crtc {
enum plane plane;
u8 lut_r[256], lut_g[256], lut_b[256];
int dpms_mode;
- bool active; /* is the crtc on? independent of the dpms mode */
+ /*
+ * Whether the crtc and the connected output pipeline is active. Implies
+ * that crtc->enabled is set, i.e. the current mode configuration has
+ * some outputs connected to this crtc.
+ *
+ * Atm crtc->enabled is unconditionally updated _before_ the hw state is
+ * changed, hence we can only check this when enabling the crtc.
+ */
+ bool active;
bool primary_disabled; /* is the crtc obscured by a plane? */
bool busy; /* is scanout buffer being updated frequently? */
struct timer_list idle_timer;
--
1.7.7.6