diff options
| author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2017-05-15 11:11:36 +0200 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2017-05-23 16:36:06 +0200 |
| commit | 9f800214731fddb0a99810bcd1af8d93d22076e0 (patch) | |
| tree | 97af8b91aca3d6309fb55acf46da8ec6cdefa39f /include | |
| parent | 9de5d4a61cc2a99634e3b51bda0f8e2fdd8f4287 (diff) | |
drm/doc: Clarify mode_fixup vs. atomic_check a bit more
Brought up by both Laurent and Andrzej when reviewing the new
->mode_valid hooks. Since mode_fixup is just a simpler version of the
much more generic atomic_check we can't really unify it with
mode_valid. Most drivers should probably switch their current
mode_fixup code to either the new mode_valid or the atomic_check
hooks, but e.g. that doesn't exist yet for bridges, and for CRTCs the
situation is a bit more complicated. Hence there's no clear
equivalence between mode_fixup and mode_valid, even if it looks like
that at first glance.
v2: Fix accidental double-dot (Adnrzej).
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Jose Abreu <Jose.Abreu@synopsys.com>
Reviewed-by: Jose Abreu <joabreu@synopsys.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170515091136.26307-2-daniel.vetter@ffwll.ch
Diffstat (limited to 'include')
| -rw-r--r-- | include/drm/drm_modeset_helper_vtables.h | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h index 361240ca738e..85984b208218 100644 --- a/include/drm/drm_modeset_helper_vtables.h +++ b/include/drm/drm_modeset_helper_vtables.h @@ -165,7 +165,11 @@ struct drm_crtc_helper_funcs { * allowed. * * Atomic drivers which need to inspect and adjust more state should - * instead use the @atomic_check callback. + * instead use the @atomic_check callback, but note that they're not + * perfectly equivalent: @mode_valid is called from + * drm_atomic_helper_check_modeset(), but @atomic_check is called from + * drm_atomic_helper_check_planes(), because originally it was meant for + * plane update checks only. * * Also beware that userspace can request its own custom modes, neither * core nor helpers filter modes to the list of probe modes reported by @@ -547,7 +551,9 @@ struct drm_encoder_helper_funcs { * allowed. * * Atomic drivers which need to inspect and adjust more state should - * instead use the @atomic_check callback. + * instead use the @atomic_check callback. If @atomic_check is used, + * this hook isn't called since @atomic_check allows a strict superset + * of the functionality of @mode_fixup. * * Also beware that userspace can request its own custom modes, neither * core nor helpers filter modes to the list of probe modes reported by @@ -734,6 +740,11 @@ struct drm_encoder_helper_funcs { * update the CRTC to match what the encoder needs for the requested * connector. * + * Since this provides a strict superset of the functionality of + * @mode_fixup (the requested and adjusted modes are both available + * through the passed in &struct drm_crtc_state) @mode_fixup is not + * called when @atomic_check is implemented. + * * This function is used by the atomic helpers, but it is optional. * * NOTE: |