Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755383AbcJMOzZ (ORCPT ); Thu, 13 Oct 2016 10:55:25 -0400 Received: from mail-yb0-f194.google.com ([209.85.213.194]:34543 "EHLO mail-yb0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752463AbcJMOzQ (ORCPT ); Thu, 13 Oct 2016 10:55:16 -0400 MIME-Version: 1.0 In-Reply-To: <1476352028-16701-1-git-send-email-brian.starkey@arm.com> References: <20161012065618.GI20761@phenom.ffwll.local> <1476352028-16701-1-git-send-email-brian.starkey@arm.com> From: Alex Deucher Date: Thu, 13 Oct 2016 10:54:51 -0400 Message-ID: Subject: Re: [PATCH] drm: atomic: Clarify documentation around drm_atomic_crtc_needs_modeset To: Brian Starkey Cc: Daniel Vetter , Maling list - DRI developers , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4752 Lines: 103 On Thu, Oct 13, 2016 at 5:47 AM, Brian Starkey wrote: > Add some additional comments to more explicitly describe the meaning and > usage of the three CRTC modeset detection booleans: mode_changed, > connectors_changed and active_changed. > > Suggested-by: Daniel Vetter > Signed-off-by: Brian Starkey > --- > > Hi Daniel, > > I guess I asked for this one :-), please just check my understanding > is correct. > The whole thread was very enlightening for me with respect to those flags as well. The patch looks good to me. Acked-by: Alex Deucher > Thanks, > Brian > > drivers/gpu/drm/drm_atomic_helper.c | 9 +++++---- > include/drm/drm_atomic.h | 11 ++++++++++- > include/drm/drm_crtc.h | 5 +++++ > 3 files changed, 20 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > index 78ea735..fb4071a 100644 > --- a/drivers/gpu/drm/drm_atomic_helper.c > +++ b/drivers/gpu/drm/drm_atomic_helper.c > @@ -458,10 +458,11 @@ mode_fixup(struct drm_atomic_state *state) > * removed from the crtc. > * crtc_state->active_changed is set when crtc_state->active changes, > * which is used for dpms. > + * See also: drm_atomic_crtc_needs_modeset() > * > * IMPORTANT: > * > - * Drivers which update ->mode_changed (e.g. in their ->atomic_check hooks if a > + * Drivers which set ->mode_changed (e.g. in their ->atomic_check hooks if a > * plane update can't be done without a full modeset) _must_ call this function > * afterwards after that change. It is permitted to call this function multiple > * times for the same update, e.g. when the ->atomic_check functions depend upon > @@ -510,9 +511,9 @@ drm_atomic_helper_check_modeset(struct drm_device *dev, > > for_each_connector_in_state(state, connector, connector_state, i) { > /* > - * This only sets crtc->mode_changed for routing changes, > - * drivers must set crtc->mode_changed themselves when connector > - * properties need to be updated. > + * This only sets crtc->connectors_changed for routing changes, > + * drivers must set crtc->connectors_changed themselves when > + * connector properties need to be updated. > */ > ret = update_connector_routing(state, connector, > connector_state); > diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h > index d9aff06..1ce255f 100644 > --- a/include/drm/drm_atomic.h > +++ b/include/drm/drm_atomic.h > @@ -368,8 +368,17 @@ int __must_check drm_atomic_nonblocking_commit(struct drm_atomic_state *state); > * > * To give drivers flexibility struct &drm_crtc_state has 3 booleans to track > * whether the state CRTC changed enough to need a full modeset cycle: > - * connectors_changed, mode_changed and active_change. This helper simply > + * connectors_changed, mode_changed and active_changed. This helper simply > * combines these three to compute the overall need for a modeset for @state. > + * > + * The atomic helper code sets these booleans, but drivers can and should > + * change them appropriately to accurately represent whether a modeset is > + * really needed. In general, drivers should avoid full modesets whenever > + * possible. > + * > + * For example if the CRTC mode has changed, and the hardware is able to enact > + * the requested mode change without going through a full modeset, the driver > + * should clear mode_changed during its ->atomic_check. > */ > static inline bool > drm_atomic_crtc_needs_modeset(struct drm_crtc_state *state) > diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h > index c4a3164..1f094d2 100644 > --- a/include/drm/drm_crtc.h > +++ b/include/drm/drm_crtc.h > @@ -116,6 +116,11 @@ struct drm_plane_helper_funcs; > * never return in a failure from the ->atomic_check callback. Userspace assumes > * that a DPMS On will always succeed. In other words: @enable controls resource > * assignment, @active controls the actual hardware state. > + * > + * The three booleans active_changed, connectors_changed and mode_changed are > + * intended to indicate whether a full modeset is needed, rather than strictly > + * describing what has changed in a commit. > + * See also: drm_atomic_crtc_needs_modeset() > */ > struct drm_crtc_state { > struct drm_crtc *crtc; > -- > 1.7.9.5 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel