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: Pekka Paalanen pekka.paalanen@collabora.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Leandro Ribeiro leandro.ribeiro@collabora.com --- include/drm/drm_property.h | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/include/drm/drm_property.h b/include/drm/drm_property.h index bbf5c1fdd7b0..f3ea7f97f372 100644 --- a/include/drm/drm_property.h +++ b/include/drm/drm_property.h @@ -37,6 +37,11 @@ * * For enumeration and bitmask properties this structure stores the symbolic * decoding for each value. This is used for example for the rotation property. + * + * 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``. */ struct drm_property_enum { uint64_t value;
On Wed, Jul 21, 2021 at 06:51:30AM +0000, Simon Ser wrote:
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: Pekka Paalanen pekka.paalanen@collabora.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Leandro Ribeiro leandro.ribeiro@collabora.com
include/drm/drm_property.h | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/include/drm/drm_property.h b/include/drm/drm_property.h index bbf5c1fdd7b0..f3ea7f97f372 100644 --- a/include/drm/drm_property.h +++ b/include/drm/drm_property.h @@ -37,6 +37,11 @@
- For enumeration and bitmask properties this structure stores the symbolic
- decoding for each value. This is used for example for the rotation property.
- 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``.
Please move this into an inline comment to make it clear that this is specifically about @value. With that:
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
I was also pondering whether we have a nice place to link to for "property's value" but really they're just uint64_t all over the place, and only stored in the drm_mode_object for non-atomic properties. So wording sounds like the best option we have.
*/ struct drm_property_enum { uint64_t value; -- 2.32.0
On Wed, 21 Jul 2021 13:43:05 +0200 Daniel Vetter daniel@ffwll.ch wrote:
On Wed, Jul 21, 2021 at 06:51:30AM +0000, Simon Ser wrote:
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: Pekka Paalanen pekka.paalanen@collabora.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Leandro Ribeiro leandro.ribeiro@collabora.com
include/drm/drm_property.h | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/include/drm/drm_property.h b/include/drm/drm_property.h index bbf5c1fdd7b0..f3ea7f97f372 100644 --- a/include/drm/drm_property.h +++ b/include/drm/drm_property.h @@ -37,6 +37,11 @@
- For enumeration and bitmask properties this structure stores the symbolic
- decoding for each value. This is used for example for the rotation property.
- 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``.
Please move this into an inline comment to make it clear that this is specifically about @value. With that:
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
With that
Acked-by: Pekka Paalanen pekka.paalanen@collabora.com
Thanks, pq
I was also pondering whether we have a nice place to link to for "property's value" but really they're just uint64_t all over the place, and only stored in the drm_mode_object for non-atomic properties. So wording sounds like the best option we have.
*/ struct drm_property_enum { uint64_t value; -- 2.32.0
dri-devel@lists.freedesktop.org
-
Daniel Vetter -
Pekka Paalanen -
Simon Ser