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path: root/drivers/gpu/drm/drm_plane.c
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Diffstat (limited to 'drivers/gpu/drm/drm_plane.c')
-rw-r--r--drivers/gpu/drm/drm_plane.c18
1 files changed, 17 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index 0dd43882fe7c..b373958ecb30 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -128,6 +128,13 @@
* pairs supported by this plane. The blob is a struct
* drm_format_modifier_blob. Without this property the plane doesn't
* support buffers with modifiers. Userspace cannot change this property.
+ *
+ * Note that userspace can check the &DRM_CAP_ADDFB2_MODIFIERS driver
+ * capability for general modifier support. If this flag is set then every
+ * plane will have the IN_FORMATS property, even when it only supports
+ * DRM_FORMAT_MOD_LINEAR. Before linux kernel release v5.1 there have been
+ * various bugs in this area with inconsistencies between the capability
+ * flag and per-plane properties.
*/
static unsigned int drm_num_planes(struct drm_device *dev)
@@ -277,8 +284,14 @@ static int __drm_universal_plane_init(struct drm_device *dev,
format_modifier_count++;
}
- if (format_modifier_count)
+ /* autoset the cap and check for consistency across all planes */
+ if (format_modifier_count) {
+ drm_WARN_ON(dev, !config->allow_fb_modifiers &&
+ !list_empty(&config->plane_list));
config->allow_fb_modifiers = true;
+ } else {
+ drm_WARN_ON(dev, config->allow_fb_modifiers);
+ }
plane->modifier_count = format_modifier_count;
plane->modifiers = kmalloc_array(format_modifier_count,
@@ -360,6 +373,9 @@ static int __drm_universal_plane_init(struct drm_device *dev,
* drm_universal_plane_init() to let the DRM managed resource infrastructure
* take care of cleanup and deallocation.
*
+ * Drivers supporting modifiers must set @format_modifiers on all their planes,
+ * even those that only support DRM_FORMAT_MOD_LINEAR.
+ *
* Returns:
* Zero on success, error code on failure.
*/