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authorSimon Ser <contact@emersion.fr>2021-07-21 09:51:30 +0300
committerSimon Ser <contact@emersion.fr>2021-07-26 11:08:22 +0300
commit3012248fdfeec400accef73bd2957f6d12f87234 (patch)
treee3481861ed609db82198a3d4fef1f9c588dbd370 /include/drm
parent03b7c552d081b73ba814eefc257c704b4d096d93 (diff)
downloadlinux-3012248fdfeec400accef73bd2957f6d12f87234.tar.xz
drm: document drm_property_enum.value for bitfields
When a property has the type DRM_MODE_PROP_BITMASK, the value field stores a bitshift, not a bitmask, which can be surprising. Signed-off-by: Simon Ser <contact@emersion.fr> Cc: Leandro Ribeiro <leandro.ribeiro@collabora.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com> Link: https://patchwork.freedesktop.org/patch/msgid/NUZTPTKKZtAlDhxIXFB1qrUqWBYKapkBxCnb1S1bc3g@cp3-web-033.plabs.ch
Diffstat (limited to 'include/drm')
-rw-r--r--include/drm/drm_property.h9
1 files changed, 8 insertions, 1 deletions
diff --git a/include/drm/drm_property.h b/include/drm/drm_property.h
index bbf5c1fdd7b0..65bc9710a470 100644
--- a/include/drm/drm_property.h
+++ b/include/drm/drm_property.h
@@ -31,7 +31,6 @@
/**
* struct drm_property_enum - symbolic values for enumerations
- * @value: numeric property value for this enum entry
* @head: list of enum values, linked to &drm_property.enum_list
* @name: symbolic name for the enum
*
@@ -39,6 +38,14 @@
* decoding for each value. This is used for example for the rotation property.
*/
struct drm_property_enum {
+ /**
+ * @value: numeric property value for this enum entry
+ *
+ * If the property has the type &DRM_MODE_PROP_BITMASK, @value stores a
+ * bitshift, not a bitmask. In other words, the enum entry is enabled
+ * if the bit number @value is set in the property's value. This enum
+ * entry has the bitmask ``1 << value``.
+ */
uint64_t value;
struct list_head head;
char name[DRM_PROP_NAME_LEN];