Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [High] drm/bridge_connector: unconditional SRO hooks with no-op readout when unsupported --
commit b75d5f60d55bc26fbc8505149b2ac1fa7543a9a1 Author: Maxime Ripard <[email protected]> drm/bridge_connector: Implement hw readout for connector This commit adds hardware state readout support to drm_bridge_connector by introducing DRM_BRIDGE_OP_CONNECTOR_HW_READOUT and the atomic_sro_connector_readout callback on drm_bridge_funcs. > diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c > b/drivers/gpu/drm/display/drm_bridge_connector.c > index 81f3e26f6fdf5..45806ef077081 100644 > --- a/drivers/gpu/drm/display/drm_bridge_connector.c > +++ b/drivers/gpu/drm/display/drm_bridge_connector.c [ ... ] > @@ -244,6 +253,26 @@ drm_bridge_connector_create_state(struct drm_connector > *connector) > return conn_state; > } > > +static int > +drm_bridge_connector_readout_state(struct drm_connector *connector, > + struct drm_atomic_sro_state *state, > + struct drm_connector_state *conn_state) > +{ > + struct drm_bridge_connector *bridge_connector = > + to_drm_bridge_connector(connector); > + struct drm_bridge *readout = > + bridge_connector->bridge_connector_hw_readout; > + int ret; > + > + if (readout) { > + ret = readout->funcs->atomic_sro_connector_readout(readout, > state, conn_state); > + if (ret) > + return ret; > + } > + > + return 0; > +} > + > static enum drm_connector_color_format > drm_bridge_connector_color_format(const struct drm_connector_state > *conn_state) > { > @@ -270,6 +299,8 @@ drm_bridge_connector_color_format(const struct > drm_connector_state *conn_state) > static const struct drm_connector_funcs drm_bridge_connector_funcs = { > .fill_modes = drm_helper_probe_single_connector_modes, > .atomic_create_state = drm_bridge_connector_create_state, > + .atomic_sro_readout_state = drm_bridge_connector_readout_state, > + .atomic_sro_compare_state = drm_atomic_helper_connector_compare_state, [Severity: High] Does unconditionally setting .atomic_sro_readout_state and .atomic_sro_compare_state on drm_bridge_connector_funcs while returning 0 in drm_bridge_connector_readout_state() when bridge_connector_hw_readout is NULL cause a regression for bridge chains without DRM_BRIDGE_OP_CONNECTOR_HW_READOUT? In drivers/gpu/drm/drm_atomic_state_readout.c, drm_atomic_sro_can_readout() and drm_atomic_sro_can_compare() determine whether a connector supports state readout by checking whether its callbacks are populated: drivers/gpu/drm/drm_atomic_state_readout.c:drm_atomic_sro_can_readout() { ... drm_connector_list_iter_begin(dev, &conn_iter); drm_for_each_connector_iter(connector, &conn_iter) { if (!connector->funcs->atomic_sro_readout_state) { drm_dbg_atomic(dev, "Connector %s missing readout callback", connector->name); drm_connector_list_iter_end(&conn_iter); return false; } } drm_connector_list_iter_end(&conn_iter); ... } Because drm_bridge_connector_funcs always defines both callbacks, every drm_bridge_connector is treated as supporting hardware state readout even when no bridge in the chain sets DRM_BRIDGE_OP_CONNECTOR_HW_READOUT (leaving bridge_connector->bridge_connector_hw_readout NULL). When state readout runs on a pipeline where bridge_connector_hw_readout is NULL (for example, when bridges implement private state readout without any bridge setting DRM_BRIDGE_OP_CONNECTOR_HW_READOUT, on a multi-connector device where only one bridge chain supports connector readout, or when drm.atomic_readout is set to DRM_ATOMIC_READOUT_SKIP_MISSING_READOUT), drm_bridge_connector_readout_state() silently returns 0 and leaves conn_state->crtc and conn_state->best_encoder set to NULL. During initial readout in drm_mode_config_create_initial_state() -> drm_atomic_helper_sro_readout_state() -> drm_atomic_helper_sro_build_state(), this causes drm_bridge_atomic_readout_priv_state() in drivers/gpu/drm/drm_bridge.c to skip reading out all bridges on that encoder's chain because find_connector_state_for_encoder() matches encoder against conn_state->best_encoder: drivers/gpu/drm/drm_bridge.c:drm_bridge_atomic_readout_priv_state() { ... conn_state = find_connector_state_for_encoder(state, encoder); if (!conn_state) return 0; if (!conn_state->crtc) return 0; ... } It also installs an inconsistent atomic state via drm_atomic_sro_install_state() with an active CRTC (crtc_state->active == true and crtc_state->connector_mask == 0) and a disconnected connector state instead of failing readout and falling back to hw_reset(). Furthermore, during post-commit verification in commit_tail() -> drm_atomic_sro_readout_and_compare(), every blocking commit enabling that connector compares the committed active state against the unpopulated readout state via drm_atomic_helper_connector_compare_state(), drm_atomic_helper_crtc_compare_state(), and drm_atomic_helper_bridge_compare_state(), triggering state mismatch errors. Should drm_bridge_connector_init() only expose a drm_connector_funcs table with .atomic_sro_readout_state and .atomic_sro_compare_state when bridge_connector->bridge_connector_hw_readout is non-NULL (similar to how drm_bridge_attach() selects between drm_bridge_priv_state_funcs and drm_bridge_priv_state_funcs_with_sro)? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=28
