| Message ID | 20221207-rpi-hdmi-improvements-v1-2-6b15f774c13a@cerno.tech (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/vc4: hdmi: Broadcast RGB, BT601, BT2020 | expand |
Hi Am 07.12.22 um 17:07 schrieb Maxime Ripard: > None of our wrappers around container_of to access our objects from the > DRM object pointer actually modify the latter. > > Let's make them const. > > Signed-off-by: Maxime Ripard <maxime@cerno.tech> Personally, I wouldn't take this patch as it does an implicit const cast on the pointer. For const correctness, it seems better to add new helpers that keep the const. Those could be use in places where the caller is not allowed to modify the state (i.e., atomic_update, et al). Something like this: const struct vc4_hdmi * const_connector_to_vc4_hdmi(const struct drm_connector *connector) { return container_of(connector, const struct vc4_hdmi, connector); } Best regards Thomas > --- > drivers/gpu/drm/vc4/vc4_hdmi.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h > index dc3ccd8002a0..023ea64ef006 100644 > --- a/drivers/gpu/drm/vc4/vc4_hdmi.h > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h > @@ -224,13 +224,13 @@ struct vc4_hdmi { > }; > > static inline struct vc4_hdmi * > -connector_to_vc4_hdmi(struct drm_connector *connector) > +connector_to_vc4_hdmi(const struct drm_connector *connector) > { > return container_of(connector, struct vc4_hdmi, connector); > } > > static inline struct vc4_hdmi * > -encoder_to_vc4_hdmi(struct drm_encoder *encoder) > +encoder_to_vc4_hdmi(const struct drm_encoder *encoder) > { > struct vc4_encoder *_encoder = to_vc4_encoder(encoder); > return container_of(_encoder, struct vc4_hdmi, encoder); > @@ -244,7 +244,7 @@ struct vc4_hdmi_connector_state { > }; > > static inline struct vc4_hdmi_connector_state * > -conn_state_to_vc4_hdmi_conn_state(struct drm_connector_state *conn_state) > +conn_state_to_vc4_hdmi_conn_state(const struct drm_connector_state *conn_state) > { > return container_of(conn_state, struct vc4_hdmi_connector_state, base); > } >
On Wed, 11 Jan 2023, Thomas Zimmermann <tzimmermann@suse.de> wrote: > Hi > > Am 07.12.22 um 17:07 schrieb Maxime Ripard: >> None of our wrappers around container_of to access our objects from the >> DRM object pointer actually modify the latter. >> >> Let's make them const. >> >> Signed-off-by: Maxime Ripard <maxime@cerno.tech> > > Personally, I wouldn't take this patch as it does an implicit const cast > on the pointer. > > For const correctness, it seems better to add new helpers that keep the > const. Those could be use in places where the caller is not allowed to > modify the state (i.e., atomic_update, et al). > > Something like this: > > const struct vc4_hdmi * > const_connector_to_vc4_hdmi(const struct drm_connector *connector) > { > return container_of(connector, const struct vc4_hdmi, > connector); > } See container_of_const(). BR, Jani. > > Best regards > Thomas > >> --- >> drivers/gpu/drm/vc4/vc4_hdmi.h | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h >> index dc3ccd8002a0..023ea64ef006 100644 >> --- a/drivers/gpu/drm/vc4/vc4_hdmi.h >> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h >> @@ -224,13 +224,13 @@ struct vc4_hdmi { >> }; >> >> static inline struct vc4_hdmi * >> -connector_to_vc4_hdmi(struct drm_connector *connector) >> +connector_to_vc4_hdmi(const struct drm_connector *connector) >> { >> return container_of(connector, struct vc4_hdmi, connector); >> } >> >> static inline struct vc4_hdmi * >> -encoder_to_vc4_hdmi(struct drm_encoder *encoder) >> +encoder_to_vc4_hdmi(const struct drm_encoder *encoder) >> { >> struct vc4_encoder *_encoder = to_vc4_encoder(encoder); >> return container_of(_encoder, struct vc4_hdmi, encoder); >> @@ -244,7 +244,7 @@ struct vc4_hdmi_connector_state { >> }; >> >> static inline struct vc4_hdmi_connector_state * >> -conn_state_to_vc4_hdmi_conn_state(struct drm_connector_state *conn_state) >> +conn_state_to_vc4_hdmi_conn_state(const struct drm_connector_state *conn_state) >> { >> return container_of(conn_state, struct vc4_hdmi_connector_state, base); >> } >>
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h index dc3ccd8002a0..023ea64ef006 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.h +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h @@ -224,13 +224,13 @@ struct vc4_hdmi { }; static inline struct vc4_hdmi * -connector_to_vc4_hdmi(struct drm_connector *connector) +connector_to_vc4_hdmi(const struct drm_connector *connector) { return container_of(connector, struct vc4_hdmi, connector); } static inline struct vc4_hdmi * -encoder_to_vc4_hdmi(struct drm_encoder *encoder) +encoder_to_vc4_hdmi(const struct drm_encoder *encoder) { struct vc4_encoder *_encoder = to_vc4_encoder(encoder); return container_of(_encoder, struct vc4_hdmi, encoder); @@ -244,7 +244,7 @@ struct vc4_hdmi_connector_state { }; static inline struct vc4_hdmi_connector_state * -conn_state_to_vc4_hdmi_conn_state(struct drm_connector_state *conn_state) +conn_state_to_vc4_hdmi_conn_state(const struct drm_connector_state *conn_state) { return container_of(conn_state, struct vc4_hdmi_connector_state, base); }
None of our wrappers around container_of to access our objects from the DRM object pointer actually modify the latter. Let's make them const. Signed-off-by: Maxime Ripard <maxime@cerno.tech> --- drivers/gpu/drm/vc4/vc4_hdmi.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)