[PATCH v8 03/14] drm/property: add a per-connector luminance flag

[Mario Limonciello <mario.limonciello@amd.com>]

The upcoming per-connector LUMINANCE range property needs to accept the
value 0 (to turn the display off on DPMS-off) even when its advertised
minimum is 1. The existing check special-cased a single device-wide
property object, which does not work once every connector owns its own
LUMINANCE property.

Add a kernel-internal is_luminance flag on struct drm_property and key
the value-0 exception off it instead of a pointer comparison. The flag
is not exposed to userspace.

Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
 drivers/gpu/drm/drm_property.c |  6 ++++++
 include/drm/drm_property.h     | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/drm_property.c b/drivers/gpu/drm/drm_property.c
index f38f2c5437e68..adccee10cfde4 100644
--- a/drivers/gpu/drm/drm_property.c
+++ b/drivers/gpu/drm/drm_property.c
@@ -952,6 +952,12 @@ bool drm_property_change_valid_get(struct drm_property *property,
 	*ref = NULL;
 
 	if (drm_property_type_is(property, DRM_MODE_PROP_RANGE)) {
+		/*
+		 * Special case for the luminance property: allow 0 to turn the
+		 * display off even when the normal range starts at 1.
+		 */
+		if (property->is_luminance && value == 0 && property->values[1] > 0)
+			return true;
 		if (value < property->values[0] || value > property->values[1])
 			return false;
 		return true;
diff --git a/include/drm/drm_property.h b/include/drm/drm_property.h
index aa49b5a42bb56..8bb568a4cd485 100644
--- a/include/drm/drm_property.h
+++ b/include/drm/drm_property.h
@@ -188,6 +188,16 @@ struct drm_property {
 	 */
 	struct drm_device *dev;
 
+	/**
+	 * @is_luminance:
+	 *
+	 * True for the per-connector LUMINANCE range property. Such a property
+	 * additionally accepts the value 0 (to turn the display off) even when
+	 * its minimum is 1. This is a kernel-internal flag and is not exposed
+	 * to userspace.
+	 */
+	bool is_luminance;
+
 	/**
 	 * @enum_list:
 	 *
-- 
2.43.0