User-space expects to be able to pick a primary plane for each CRTC
exposed by the driver. Make sure this assumption holds in
drm_mode_config_validate.
Use the legacy drm_crtc.primary field to check this, because it's
simpler and we require drivers to set it anyways. Accumulate a set of
primary planes which are already used for a CRTC in a bitmask. Error out
if a primary plane is re-used.
Signed-off-by: Simon Ser <cont...@emersion.fr>
Cc: Daniel Vetter <dan...@ffwll.ch>
Cc: Pekka Paalanen <ppaala...@gmail.com>
---
drivers/gpu/drm/drm_mode_config.c | 21 +++++++++++++++++++++
drivers/gpu/drm/drm_plane.c | 6 ++++++
2 files changed, 27 insertions(+)
diff --git a/drivers/gpu/drm/drm_mode_config.c
b/drivers/gpu/drm/drm_mode_config.c
index fbe680035129..f143f56f0820 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -626,6 +626,9 @@ void drm_mode_config_validate(struct drm_device *dev)
{
struct drm_encoder *encoder;
struct drm_crtc *crtc;
+ struct drm_plane *plane;
+ __u64 primary_with_crtc = 0, cursor_with_crtc = 0;
+ unsigned num_primary = 0;
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return;
@@ -647,12 +650,30 @@ void drm_mode_config_validate(struct drm_device *dev)
"Bogus primary plane possible_crtcs: [PLANE:%d:%s]
must be compatible with [CRTC:%d:%s]\n",
crtc->primary->base.id, crtc->primary->name,
crtc->base.id, crtc->name);
+ WARN(primary_with_crtc & BIT(crtc->primary->index),
+ "Primary plane [PLANE:%d:%s] used for two CRTCs",
+ crtc->primary->base.id, crtc->primary->name);
+ primary_with_crtc |= BIT(crtc->primary->index);
}
if (crtc->cursor) {
WARN(!(crtc->cursor->possible_crtcs & BIT(crtc->index)),
"Bogus cursor plane possible_crtcs: [PLANE:%d:%s]
must be compatible with [CRTC:%d:%s]\n",
crtc->cursor->base.id, crtc->cursor->name,
crtc->base.id, crtc->name);
+ WARN(cursor_with_crtc & BIT(crtc->cursor->index),
+ "Primary plane [PLANE:%d:%s] used for two CRTCs",
+ crtc->cursor->base.id, crtc->cursor->name);
+ cursor_with_crtc |= BIT(crtc->cursor->index);
}
}
+
+ drm_for_each_plane(plane, dev) {
+ if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
+ num_primary++;
+ }
+ }
+
+ WARN(num_primary != dev->mode_config.num_crtc,
+ "Must have as many primary planes as there are CRTCs, but have %u
primary planes and %u CRTCs",
+ num_primary, dev->mode_config.num_crtc);
}
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index 49b0a8b9ac02..a1f4510efa83 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -54,6 +54,12 @@
* enum drm_plane_type). A plane can be compatible with multiple CRTCs, see
* &drm_plane.possible_crtcs.
*
+ * Each CRTC must have a unique primary plane userspace can attach to enable
+ * the CRTC. In other words, userspace must be able to attach a different
+ * primary plane to each CRTC at the same time. Primary planes can still be
+ * compatible with multiple CRTCs. There must be exactly as many primary planes
+ * as there are CRTCs.
+ *
* Legacy uAPI doesn't expose the primary and cursor planes directly. DRM core
* relies on the driver to set the primary and optionally the cursor plane used
* for legacy IOCTLs. This is done by calling drm_crtc_init_with_planes(). All
--
2.29.2
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