drm/probe-helper: Introduce .force_ctx() connector callback

The .force() connector callback is invoked by
drm_helper_probe_single_connector_modes() while the modeset acquire
context it created is live, but the hook signature provides no way to
pass it down, e.g. to support implementations needing to lock further
objects.

Add a .force_ctx() variant to drm_connector_helper_funcs, taking the
acquire context and returning an error code, so that -EDEADLK propagates
into the existing retry path.  When provided, it takes precedence over
drm_connector_funcs' .force(), which is kept for existing users.

This is a prerequisite for SCDC status synchronization in the HDMI
connector framework.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patch.msgid.link/20260901-dw-hdmi-qp-scramb-v11-6-bc12954a0688@collabora.com
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>

2 files changed, 34 insertions, 0 deletions

diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index be51265e8e26..f2be06f12b1a 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1670,6 +1670,12 @@ struct drm_connector_funcs {
 	 * the sysfs interfaces or on the kernel cmdline. In that case the
 	 * @detect callback isn't called.
 	 *
+	 * New drivers should implement
+	 * &drm_connector_helper_funcs.force_ctx instead, which gets passed
+	 * the modeset acquire context and thus allows taking additional
+	 * locks.  It takes precedence over this callback when both are
+	 * implemented.
+	 *
 	 * FIXME:
 	 *
 	 * Note that this hook is only called by the probe helper. It's not in
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index dc4c5e8733c3..60b30cc26940 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -936,6 +936,34 @@ struct drm_connector_helper_funcs {
 			  bool force);
 
 	/**
+	 * @force_ctx:
+	 *
+	 * This function is called to update internal encoder state when the
+	 * connector is forced to a certain state by userspace, either through
+	 * the sysfs interfaces or on the kernel cmdline. In that case the
+	 * @detect_ctx callback isn't called.
+	 *
+	 * This is the atomic version of &drm_connector_funcs.force.  When
+	 * both are implemented, this one takes precedence and
+	 * &drm_connector_funcs.force is not called.
+	 *
+	 * To avoid races against concurrent connector state updates, the
+	 * helper libraries always call this with ctx set to a valid context,
+	 * and &drm_mode_config.connection_mutex will always be locked with
+	 * the ctx parameter set to this ctx. This allows taking additional
+	 * locks as required.
+	 *
+	 * RETURNS:
+	 *
+	 * Zero on success, or a negative error code otherwise.  This includes
+	 * -EDEADLK when a lock acquisition needs to be restarted, in which
+	 * case the helpers take care of backing off and calling this function
+	 * again.
+	 */
+	int (*force_ctx)(struct drm_connector *connector,
+			 struct drm_modeset_acquire_ctx *ctx);
+
+	/**
 	 * @mode_valid:
 	 *
 	 * Callback to validate a mode for a connector, irrespective of the