Unverified Commit 96962e3d authored by Simon Ser's avatar Simon Ser
Browse files

drm: require each CRTC to have a unique primary plane 



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.

v2: new patch

v3:
- Use u64 instead of __u64 (Jani)
- Use `unsigned int` instead of `unsigned` (Jani)

v4:
- Use u32 instead of u64 for plane mask (Ville)
- Use drm_plane_mask instead of BIT (Ville)
- Fix typos (Ville)

Signed-off-by: default avatarSimon Ser <contact@emersion.fr>
Reviewed-by: default avatarDaniel Vetter <daniel@ffwll.ch>
Acked-by: default avatarVille Syrjala <ville.syrjala@linux.intel.com>
Cc: Pekka Paalanen <ppaalanen@gmail.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201211184634.74534-4-contact@emersion.fr
parent a7ecf003

drivers/gpu/drm/drm_mode_config.c

+20 −0
Original line number Diff line number Diff line
@@ -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;

	u32 primary_with_crtc = 0, cursor_with_crtc = 0;

	unsigned int num_primary = 0;



	if (!drm_core_check_feature(dev, DRIVER_MODESET))

		return;
@@ -647,12 +650,29 @@ 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 & drm_plane_mask(crtc->primary),

			     "Primary plane [PLANE:%d:%s] used for multiple CRTCs",

			     crtc->primary->base.id, crtc->primary->name);

			primary_with_crtc |= drm_plane_mask(crtc->primary);

		}

		if (crtc->cursor) {

			WARN(!(crtc->cursor->possible_crtcs & drm_crtc_mask(crtc)),

			     "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 & drm_plane_mask(crtc->cursor),

			     "Cursor plane [PLANE:%d:%s] used for multiple CRTCs",

			     crtc->cursor->base.id, crtc->cursor->name);

			cursor_with_crtc |= drm_plane_mask(crtc->cursor);

		}

	}



	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);

}

drivers/gpu/drm/drm_plane.c

+6 −0
Original line number Diff line number Diff line
@@ -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