This patch adds docs for the ACTIVE and MODE_ID CRTC properties.
Signed-off-by: Simon Ser <contact@xxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxxxx>
Cc: Michel Dänzer <michel@xxxxxxxxxxx>
Cc: Daniel Stone <daniel@xxxxxxxxxxxxx>
---
Thanks for the review Daniel! I rejiggered your suggestions a little to
move some ACTIVE bits into the ACTIVE description.
Documentation/gpu/drm-kms.rst | 6 ++++++
drivers/gpu/drm/drm_crtc.c | 27 +++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst
index 397314d08f77..975cfeb8a353 100644
--- a/Documentation/gpu/drm-kms.rst
+++ b/Documentation/gpu/drm-kms.rst
@@ -460,6 +460,12 @@ HDMI Specific Connector Properties
.. kernel-doc:: drivers/gpu/drm/drm_connector.c
:doc: HDMI connector properties
+Standard CRTC Properties
+------------------------
+
+.. kernel-doc:: drivers/gpu/drm/drm_crtc.c
+ :doc: standard CRTC properties
+
Plane Composition Properties
----------------------------
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 4936e1080e41..fafb8d3c3235 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -204,6 +204,33 @@ struct dma_fence *drm_crtc_create_fence(struct drm_crtc *crtc)
return fence;
}
+/**
+ * DOC: standard CRTC properties
+ *
+ * DRM CRTCs have a few standardized properties:
+ *
+ * ACTIVE:
+ * Atomic property for setting the power state of the CRTC. When set to 1 the
+ * CRTC will actively display content. When set to 0 the CRTC will be powered
+ * off. There is no expectation that user-space will reset CRTC resources like
+ * the mode and planes when setting ACTIVE to 0.
+ *
+ * User-space can rely on an ACTIVE change to 1 to never fail an atomic test
+ * as long as no other property has changed. If a change to ACTIVE fails an
+ * atomic test, this is a driver bug. For this reason setting ACTIVE to 0 must
+ * not release internal resources (like reserved memory bandwidth or clock
+ * generators).
+ *
+ * Note that the legacy DPMS property on connectors is internally routed to
+ * control this property for atomic drivers.
+ * MODE_ID:
+ * Atomic property for setting the CRTC display timings. The value is the ID
+ * of a blob containing the DRM mode info. To disable the CRTC, user-space
+ * must set this property to 0.
+ *
+ * Setting MODE_ID to 0 will release reserved resources for the CRTC.
+ */
+
/**
* drm_crtc_init_with_planes - Initialise a new CRTC object with
* specified primary and cursor planes.
--
2.26.2
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