Re: [PATCH] drm: atomic helper: fix W=1 warnings

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Oct 03, 2019 at 05:37:15PM +0200, Benjamin Gaignard wrote:
> Le jeu. 3 oct. 2019 à 17:05, Ville Syrjälä
> <ville.syrjala@linux.intel.com> a écrit :
> >
> > On Thu, Oct 03, 2019 at 04:46:54PM +0200, Benjamin Gaignard wrote:
> > > Le jeu. 3 oct. 2019 à 16:27, Ville Syrjälä
> > > <ville.syrjala@linux.intel.com> a écrit :
> > > >
> > > > On Mon, Sep 09, 2019 at 03:52:05PM +0200, Benjamin Gaignard wrote:
> > > > > Fix warnings with W=1.
> > > > > Few for_each macro set variables that are never used later.
> > > > > Prevent warning by marking these variables as __maybe_unused.
> > > > >
> > > > > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
> > > > > ---
> > > > >  drivers/gpu/drm/drm_atomic_helper.c | 36 ++++++++++++++++++------------------
> > > > >  1 file changed, 18 insertions(+), 18 deletions(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > > > > index aa16ea17ff9b..b69d17b0b9bd 100644
> > > > > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > > > > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > > > > @@ -262,7 +262,7 @@ steal_encoder(struct drm_atomic_state *state,
> > > > >             struct drm_encoder *encoder)
> > > > >  {
> > > > >       struct drm_crtc_state *crtc_state;
> > > > > -     struct drm_connector *connector;
> > > > > +     struct drm_connector __maybe_unused *connector;
> > > >
> > > > Rather ugly. IMO would be nicer if we could hide something inside
> > > > the iterator macros to suppress the warning.
> > >
> > > Ok but how ?
> > > connector is assigned in the macros but not used later and we can't
> > > set "__maybe_unused"
> > > in the macro.
> > > Does another keyword exist for that ?
> >
> > Stick a (void)(connector) into the macro?
> 
> That could work but it will look strange inside the macro.

If this works I think it's fine, maybe together with a FIXME or so ... At
least as an interim solution. Much better than sprinkling all the
maybe_unused annotations around like in this patch.
-Daniel
> 
> >
> > Another (arguably cleaner) idea would be to remove the connector/crtc/plane
> > argument from the iterators entirely since it's redundant, and instead just
> > extract it from the appropriate new/old state as needed.
> >
> > We could then also add a for_each_connector_in_state()/etc. which omit
> > s the state arguments and just has the connector argument, for cases where
> > you don't care about the states when iterating.
> 
> That may lead to get a macro for each possible combination of used variables.
> 
> >
> > >
> > > >
> > > > >       struct drm_connector_state *old_connector_state, *new_connector_state;
> > > > >       int i;
> > > > >
> > > > > @@ -412,7 +412,7 @@ mode_fixup(struct drm_atomic_state *state)
> > > > >  {
> > > > >       struct drm_crtc *crtc;
> > > > >       struct drm_crtc_state *new_crtc_state;
> > > > > -     struct drm_connector *connector;
> > > > > +     struct drm_connector __maybe_unused *connector;
> > > > >       struct drm_connector_state *new_conn_state;
> > > > >       int i;
> > > > >       int ret;
> > > > > @@ -608,7 +608,7 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
> > > > >  {
> > > > >       struct drm_crtc *crtc;
> > > > >       struct drm_crtc_state *old_crtc_state, *new_crtc_state;
> > > > > -     struct drm_connector *connector;
> > > > > +     struct drm_connector __maybe_unused *connector;
> > > > >       struct drm_connector_state *old_connector_state, *new_connector_state;
> > > > >       int i, ret;
> > > > >       unsigned connectors_mask = 0;
> > > > > @@ -984,7 +984,7 @@ crtc_needs_disable(struct drm_crtc_state *old_state,
> > > > >  static void
> > > > >  disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
> > > > >  {
> > > > > -     struct drm_connector *connector;
> > > > > +     struct drm_connector __maybe_unused *connector;
> > > > >       struct drm_connector_state *old_conn_state, *new_conn_state;
> > > > >       struct drm_crtc *crtc;
> > > > >       struct drm_crtc_state *old_crtc_state, *new_crtc_state;
> > > > > @@ -1173,7 +1173,7 @@ crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *old_state)
> > > > >  {
> > > > >       struct drm_crtc *crtc;
> > > > >       struct drm_crtc_state *new_crtc_state;
> > > > > -     struct drm_connector *connector;
> > > > > +     struct drm_connector __maybe_unused *connector;
> > > > >       struct drm_connector_state *new_conn_state;
> > > > >       int i;
> > > > >
> > > > > @@ -1294,7 +1294,7 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
> > > > >       struct drm_crtc *crtc;
> > > > >       struct drm_crtc_state *old_crtc_state;
> > > > >       struct drm_crtc_state *new_crtc_state;
> > > > > -     struct drm_connector *connector;
> > > > > +     struct drm_connector __maybe_unused *connector;
> > > > >       struct drm_connector_state *new_conn_state;
> > > > >       int i;
> > > > >
> > > > > @@ -1384,7 +1384,7 @@ int drm_atomic_helper_wait_for_fences(struct drm_device *dev,
> > > > >                                     struct drm_atomic_state *state,
> > > > >                                     bool pre_swap)
> > > > >  {
> > > > > -     struct drm_plane *plane;
> > > > > +     struct drm_plane __maybe_unused *plane;
> > > > >       struct drm_plane_state *new_plane_state;
> > > > >       int i, ret;
> > > > >
> > > > > @@ -1431,7 +1431,7 @@ drm_atomic_helper_wait_for_vblanks(struct drm_device *dev,
> > > > >               struct drm_atomic_state *old_state)
> > > > >  {
> > > > >       struct drm_crtc *crtc;
> > > > > -     struct drm_crtc_state *old_crtc_state, *new_crtc_state;
> > > > > +     struct drm_crtc_state __maybe_unused *old_crtc_state, *new_crtc_state;
> > > > >       int i, ret;
> > > > >       unsigned crtc_mask = 0;
> > > > >
> > > > > @@ -1621,7 +1621,7 @@ static void commit_work(struct work_struct *work)
> > > > >  int drm_atomic_helper_async_check(struct drm_device *dev,
> > > > >                                  struct drm_atomic_state *state)
> > > > >  {
> > > > > -     struct drm_crtc *crtc;
> > > > > +     struct drm_crtc __maybe_unused *crtc;
> > > > >       struct drm_crtc_state *crtc_state;
> > > > >       struct drm_plane *plane = NULL;
> > > > >       struct drm_plane_state *old_plane_state = NULL;
> > > > > @@ -1982,9 +1982,9 @@ int drm_atomic_helper_setup_commit(struct drm_atomic_state *state,
> > > > >  {
> > > > >       struct drm_crtc *crtc;
> > > > >       struct drm_crtc_state *old_crtc_state, *new_crtc_state;
> > > > > -     struct drm_connector *conn;
> > > > > +     struct drm_connector __maybe_unused *conn;
> > > > >       struct drm_connector_state *old_conn_state, *new_conn_state;
> > > > > -     struct drm_plane *plane;
> > > > > +     struct drm_plane __maybe_unused *plane;
> > > > >       struct drm_plane_state *old_plane_state, *new_plane_state;
> > > > >       struct drm_crtc_commit *commit;
> > > > >       int i, ret;
> > > > > @@ -2214,7 +2214,7 @@ EXPORT_SYMBOL(drm_atomic_helper_fake_vblank);
> > > > >   */
> > > > >  void drm_atomic_helper_commit_hw_done(struct drm_atomic_state *old_state)
> > > > >  {
> > > > > -     struct drm_crtc *crtc;
> > > > > +     struct drm_crtc __maybe_unused *crtc;
> > > > >       struct drm_crtc_state *old_crtc_state, *new_crtc_state;
> > > > >       struct drm_crtc_commit *commit;
> > > > >       int i;
> > > > > @@ -2300,7 +2300,7 @@ EXPORT_SYMBOL(drm_atomic_helper_commit_cleanup_done);
> > > > >  int drm_atomic_helper_prepare_planes(struct drm_device *dev,
> > > > >                                    struct drm_atomic_state *state)
> > > > >  {
> > > > > -     struct drm_connector *connector;
> > > > > +     struct drm_connector __maybe_unused *connector;
> > > > >       struct drm_connector_state *new_conn_state;
> > > > >       struct drm_plane *plane;
> > > > >       struct drm_plane_state *new_plane_state;
> > > > > @@ -2953,9 +2953,9 @@ int drm_atomic_helper_disable_all(struct drm_device *dev,
> > > > >  {
> > > > >       struct drm_atomic_state *state;
> > > > >       struct drm_connector_state *conn_state;
> > > > > -     struct drm_connector *conn;
> > > > > +     struct drm_connector __maybe_unused *conn;
> > > > >       struct drm_plane_state *plane_state;
> > > > > -     struct drm_plane *plane;
> > > > > +     struct drm_plane __maybe_unused *plane;
> > > > >       struct drm_crtc_state *crtc_state;
> > > > >       struct drm_crtc *crtc;
> > > > >       int ret, i;
> > > > > @@ -3199,11 +3199,11 @@ int drm_atomic_helper_commit_duplicated_state(struct drm_atomic_state *state,
> > > > >  {
> > > > >       int i, ret;
> > > > >       struct drm_plane *plane;
> > > > > -     struct drm_plane_state *new_plane_state;
> > > > > +     struct drm_plane_state __maybe_unused *new_plane_state;
> > > > >       struct drm_connector *connector;
> > > > > -     struct drm_connector_state *new_conn_state;
> > > > > +     struct drm_connector_state __maybe_unused *new_conn_state;
> > > > >       struct drm_crtc *crtc;
> > > > > -     struct drm_crtc_state *new_crtc_state;
> > > > > +     struct drm_crtc_state __maybe_unused *new_crtc_state;
> > > > >
> > > > >       state->acquire_ctx = ctx;
> > > > >
> > > > > --
> > > > > 2.15.0
> > > > >
> > > > > _______________________________________________
> > > > > dri-devel mailing list
> > > > > dri-devel@lists.freedesktop.org
> > > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > > >
> > > > --
> > > > Ville Syrjälä
> > > > Intel
> >
> > --
> > Ville Syrjälä
> > Intel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch