From: Simon Ser Date: Wed, 21 Jul 2021 06:51:30 +0000 (+0000) Subject: drm: document drm_property_enum.value for bitfields X-Git-Tag: v5.15~303^2~22^2~35 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3012248fdfeec400accef73bd2957f6d12f87234;p=platform%2Fkernel%2Flinux-starfive.git 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 Cc: Leandro Ribeiro Reviewed-by: Daniel Vetter Acked-by: Pekka Paalanen Link: https://patchwork.freedesktop.org/patch/msgid/NUZTPTKKZtAlDhxIXFB1qrUqWBYKapkBxCnb1S1bc3g@cp3-web-033.plabs.ch --- diff --git a/include/drm/drm_property.h b/include/drm/drm_property.h index bbf5c1fd..65bc971 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];