Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756668AbcJQGYT (ORCPT ); Mon, 17 Oct 2016 02:24:19 -0400 Received: from mail-lf0-f66.google.com ([209.85.215.66]:35160 "EHLO mail-lf0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756215AbcJQGYL (ORCPT ); Mon, 17 Oct 2016 02:24:11 -0400 Date: Mon, 17 Oct 2016 08:07:37 +0200 From: Daniel Vetter To: Alex Deucher Cc: Brian Starkey , Daniel Vetter , Maling list - DRI developers , LKML Subject: Re: [PATCH] drm: atomic: Clarify documentation around drm_atomic_crtc_needs_modeset Message-ID: <20161017060737.GP20761@phenom.ffwll.local> Mail-Followup-To: Alex Deucher , Brian Starkey , Maling list - DRI developers , LKML References: <20161012065618.GI20761@phenom.ffwll.local> <1476352028-16701-1-git-send-email-brian.starkey@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux phenom 4.6.0-1-amd64 User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5136 Lines: 113 On Thu, Oct 13, 2016 at 10:54:51AM -0400, Alex Deucher wrote: > 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 Applied to drm-misc, thanks. -Daniel > > > 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 -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch