diff options
Diffstat (limited to 'drivers/gpu/drm/drm_modeset_helper.c')
| -rw-r--r-- | drivers/gpu/drm/drm_modeset_helper.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_modeset_helper.c b/drivers/gpu/drm/drm_modeset_helper.c index f1c24ab0ef09..9150fa385bba 100644 --- a/drivers/gpu/drm/drm_modeset_helper.c +++ b/drivers/gpu/drm/drm_modeset_helper.c @@ -146,6 +146,21 @@ static struct drm_plane *create_primary_plane(struct drm_device *dev) * Initialize a CRTC object with a default helper-provided primary plane and no * cursor plane. * + * Note that we make some assumptions about hardware limitations that may not be + * true for all hardware: + * + * 1. Primary plane cannot be repositioned. + * 2. Primary plane cannot be scaled. + * 3. Primary plane must cover the entire CRTC. + * 4. Subpixel positioning is not supported. + * 5. The primary plane must always be on if the CRTC is enabled. + * + * This is purely a backwards compatibility helper for old drivers. Drivers + * should instead implement their own primary plane. Atomic drivers must do so. + * Drivers with the above hardware restriction can look into using &struct + * drm_simple_display_pipe, which encapsulates the above limitations into a nice + * interface. + * * Returns: * Zero on success, error code on failure. */ |