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Fri, 17 Oct 2025 06:21:38 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:5485:d4b2:c087:b497]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b5cba06c187sm794912066b.31.2025.10.17.06.21.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Oct 2025 06:21:37 -0700 (PDT) Date: Fri, 17 Oct 2025 15:21:36 +0200 From: Simona Vetter To: Maxime Ripard Cc: Maarten Lankhorst , Thomas Zimmermann , David Airlie , Simona Vetter , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Jyri Sarha , Tomi Valkeinen , Devarsh Thakkar , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 13/29] drm/atomic_helper: Compare actual and readout states once the commit is done Message-ID: Mail-Followup-To: Maxime Ripard , Maarten Lankhorst , Thomas Zimmermann , David Airlie , Simona Vetter , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Jyri Sarha , Tomi Valkeinen , Devarsh Thakkar , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20250902-drm-state-readout-v1-0-14ad5315da3f@kernel.org> <20250902-drm-state-readout-v1-13-14ad5315da3f@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250902-drm-state-readout-v1-13-14ad5315da3f@kernel.org> X-Operating-System: Linux phenom 6.12.38+deb13-amd64 On Tue, Sep 02, 2025 at 10:32:41AM +0200, Maxime Ripard wrote: > The new atomic state readout infrastructure can be hard to test because > getting access to every firmware variation is hard, but also because > most firmware setup will be pretty basic and won't test a wide range of > features. Noticing whether it was sucessful or not is also not very > convenient. > > In order to make it easier, we can however provide some infrastructure > to read out a new state every time a non-blocking commit is made, and > compare the readout one with the committed one. And since we do this > only on non-blocking commits, the time penalty doesn't matter. > > To do so, we introduce a new hook for every state, atomic_compare_state, > that takes two state instances and is supposed to return whether they > are identical or not. > > Signed-off-by: Maxime Ripard > --- > drivers/gpu/drm/drm_atomic_helper.c | 113 ++++++++++++++++++++++++++++++++++++ > include/drm/drm_atomic.h | 14 +++++ > include/drm/drm_bridge.h | 14 +++++ > include/drm/drm_connector.h | 14 +++++ > include/drm/drm_crtc.h | 14 +++++ > include/drm/drm_plane.h | 14 +++++ > 6 files changed, 183 insertions(+) > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > index 14d9bc282ca570964e494936090898b2dc6bee31..aa8f52b5d5a5e6146a6472eebaf02e675c35ccd2 100644 > --- a/drivers/gpu/drm/drm_atomic_helper.c > +++ b/drivers/gpu/drm/drm_atomic_helper.c > @@ -428,10 +428,120 @@ void drm_atomic_helper_readout_state(struct drm_device *dev) > drm_atomic_helper_install_readout_state(state); > drm_atomic_state_put(state); > } > EXPORT_SYMBOL(drm_atomic_helper_readout_state); > > +static bool drm_atomic_helper_readout_compare(struct drm_atomic_state *committed_state) > +{ > + struct drm_device *dev = committed_state->dev; > + struct drm_printer p = drm_err_printer(dev, NULL); > + struct drm_private_state *new_obj_state; > + struct drm_private_obj *obj; > + struct drm_plane_state *new_plane_state; > + struct drm_plane *plane; > + struct drm_crtc_state *new_crtc_state; > + struct drm_crtc *crtc; > + struct drm_connector_state *new_conn_state; > + struct drm_connector *conn; > + struct drm_atomic_state *readout_state; > + unsigned int i; > + bool identical = true; > + > + readout_state = drm_atomic_build_readout_state(dev); > + if (WARN_ON(IS_ERR(readout_state))) > + return false; > + > + for_each_new_plane_in_state(committed_state, plane, new_plane_state, i) { > + const struct drm_plane_funcs *plane_funcs = > + plane->funcs; > + struct drm_plane_state *readout_plane_state; > + > + readout_plane_state = drm_atomic_get_old_plane_state(readout_state, plane); > + if (!readout_plane_state) { > + identical = false; > + continue; > + } > + > + if (!plane_funcs->atomic_compare_state) > + continue; > + > + if (!plane_funcs->atomic_compare_state(plane, &p, new_plane_state, readout_plane_state)) { > + drm_warn(dev, "[PLANE:%d:%s] Committed and Readout PLANE state don't match\n", > + plane->base.id, plane->name); > + identical = false; > + continue; > + } > + } > + > + for_each_new_crtc_in_state(committed_state, crtc, new_crtc_state, i) { > + const struct drm_crtc_funcs *crtc_funcs = crtc->funcs; > + struct drm_crtc_state *readout_crtc_state; > + > + readout_crtc_state = drm_atomic_get_old_crtc_state(readout_state, crtc); > + if (!readout_crtc_state) { > + identical = false; > + continue; > + } > + > + if (!crtc_funcs->atomic_compare_state) > + continue; > + > + if (!crtc_funcs->atomic_compare_state(crtc, &p, new_crtc_state, readout_crtc_state)) { > + drm_warn(dev, "[CRTC:%d:%s] Committed and Readout CRTC state don't match\n", > + crtc->base.id, crtc->name); > + identical = false; > + continue; > + } > + } > + > + for_each_new_connector_in_state(committed_state, conn, new_conn_state, i) { > + const struct drm_connector_funcs *conn_funcs = > + conn->funcs; > + struct drm_connector_state *readout_conn_state; > + > + readout_conn_state = drm_atomic_get_old_connector_state(readout_state, conn); > + if (!readout_conn_state) { > + identical = false; > + continue; > + } > + > + if (!conn_funcs->atomic_compare_state) > + continue; > + > + if (!conn_funcs->atomic_compare_state(conn, &p, new_conn_state, readout_conn_state)) { > + drm_warn(dev, "[CONNECTOR:%d:%s] Committed and Readout connector state don't match\n", > + conn->base.id, conn->name); > + identical = false; > + continue; > + } > + } > + > + for_each_new_private_obj_in_state(committed_state, obj, new_obj_state, i) { > + const struct drm_private_state_funcs *obj_funcs = obj->funcs; > + struct drm_private_state *readout_obj_state; > + > + readout_obj_state = drm_atomic_get_old_private_obj_state(readout_state, obj); > + if (!readout_obj_state) { > + identical = false; > + continue; > + } > + > + if (!obj_funcs->atomic_compare_state) > + continue; > + > + if (!obj_funcs->atomic_compare_state(obj, &p, new_obj_state, readout_obj_state)) { > + drm_warn(dev, "Committed and Readout private object state don't match\n"); > + identical = false; > + continue; > + } > + } > + > + drm_atomic_state_put(readout_state); > + > + return identical; > +} > + > /** > * DOC: overview > * > * This helper library provides implementations of check and commit functions on > * top of the CRTC modeset helper callbacks and the plane helper callbacks. It > @@ -2382,10 +2492,13 @@ static void commit_tail(struct drm_atomic_state *state, bool nonblock) > (unsigned long)commit_time_ms, > new_self_refresh_mask); > > drm_atomic_helper_commit_cleanup_done(state); > > + if (!nonblock) > + drm_atomic_helper_readout_compare(state); > + > drm_atomic_state_put(state); > } > > static void commit_work(struct work_struct *work) > { > diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h > index f13f926d21047e42bb9ac692c2dd4b88f2ebd91c..d75a9c7e23adf7fa264df766b47526f75e9cc753 100644 > --- a/include/drm/drm_atomic.h > +++ b/include/drm/drm_atomic.h > @@ -226,10 +226,24 @@ struct drm_private_state_funcs { > * Frees the private object state created with @atomic_duplicate_state. > */ > void (*atomic_destroy_state)(struct drm_private_obj *obj, > struct drm_private_state *state); > > + /** > + * @atomic_compare_state > + * > + * Compares two &struct drm_private_state instances. > + * > + * RETURNS: > + * > + * True if the states are identical, false otherwise. > + */ > + bool (*atomic_compare_state)(struct drm_private_obj *obj, > + struct drm_printer *p, > + struct drm_private_state *a, > + struct drm_private_state *b); > + > /** > * @atomic_print_state: > * > * If driver subclasses &struct drm_private_state, it should implement > * this optional hook for printing additional driver specific state. > diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h > index 15b63053f01869786831936ba28b7efc1e55e2e8..5ea63b51a4dd4cb00468afcf7d126c774f63ade0 100644 > --- a/include/drm/drm_bridge.h > +++ b/include/drm/drm_bridge.h > @@ -511,10 +511,24 @@ struct drm_bridge_funcs { > int (*atomic_readout_state)(struct drm_bridge *bridge, > struct drm_bridge_state *bridge_state, > struct drm_crtc_state *crtc_state, > struct drm_connector_state *conn_state); > > + /** > + * @atomic_compare_state > + * > + * Compares two &struct drm_bridge_state instances. > + * > + * RETURNS: > + * > + * True if the states are identical, false otherwise. > + */ > + bool (*atomic_compare_state)(struct drm_bridge *bridge, > + struct drm_printer *p, > + struct drm_bridge_state *a, > + struct drm_bridge_state *b); > + > /** > * @atomic_duplicate_state: > * > * Duplicate the current bridge state object (which is guaranteed to be > * non-NULL). > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h > index f68bd9627c085c6d2463b847aaa245ccc651f27b..dc2c77b04df9010cbfb2028de8ef8c747003c489 100644 > --- a/include/drm/drm_connector.h > +++ b/include/drm/drm_connector.h > @@ -1534,10 +1534,24 @@ struct drm_connector_funcs { > * This callback is mandatory for atomic drivers. > */ > void (*atomic_destroy_state)(struct drm_connector *connector, > struct drm_connector_state *state); > Both these callbacks for connector/crtc/plane need to be moved into the respective _helper_funcs structs, because they're not uapi stuff. priv/bridge funcs do not have this split, because they're not uapi visible objects. -Sima > + /** > + * @atomic_compare_state > + * > + * Compares two &struct drm_connector_state instances. > + * > + * RETURNS: > + * > + * True if the states are identical, false otherwise. > + */ > + bool (*atomic_compare_state)(struct drm_connector *connector, > + struct drm_printer *p, > + struct drm_connector_state *a, > + struct drm_connector_state *b); > + > /** > * @atomic_set_property: > * > * Decode a driver-private property value and store the decoded value > * into the passed-in state structure. Since the atomic core decodes all > diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h > index 11e3299cfad1572c6e507918c7cceae7a28ba4cf..21c20ecdda40f3d155d3c140e06b3801270f5262 100644 > --- a/include/drm/drm_crtc.h > +++ b/include/drm/drm_crtc.h > @@ -676,10 +676,24 @@ struct drm_crtc_funcs { > * This callback is mandatory for atomic drivers. > */ > void (*atomic_destroy_state)(struct drm_crtc *crtc, > struct drm_crtc_state *state); > > + /** > + * @atomic_compare_state > + * > + * Compares two &struct drm_crtc_state instances. > + * > + * RETURNS: > + * > + * True if the states are identical, false otherwise. > + */ > + bool (*atomic_compare_state)(struct drm_crtc *crtc, > + struct drm_printer *p, > + struct drm_crtc_state *a, > + struct drm_crtc_state *b); > + > /** > * @atomic_set_property: > * > * Decode a driver-private property value and store the decoded value > * into the passed-in state structure. Since the atomic core decodes all > diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h > index 691a267c857a228f674ef02a63fb6d1ff9e379a8..c24c10ccc8e8f2ba23e77e279aef61ae86e320c7 100644 > --- a/include/drm/drm_plane.h > +++ b/include/drm/drm_plane.h > @@ -449,10 +449,24 @@ struct drm_plane_funcs { > * This callback is mandatory for atomic drivers. > */ > void (*atomic_destroy_state)(struct drm_plane *plane, > struct drm_plane_state *state); > > + /** > + * @atomic_compare_state > + * > + * Compares two &struct drm_plane_state instances. > + * > + * RETURNS: > + * > + * True if the states are identical, false otherwise. > + */ > + bool (*atomic_compare_state)(struct drm_plane *plane, > + struct drm_printer *p, > + struct drm_plane_state *a, > + struct drm_plane_state *b); > + > /** > * @atomic_set_property: > * > * Decode a driver-private property value and store the decoded value > * into the passed-in state structure. Since the atomic core decodes all > > -- > 2.50.1 > -- Simona Vetter Software Engineer http://blog.ffwll.ch