From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8C0F43B5312; Mon, 16 Mar 2026 16:32:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773678742; cv=none; b=srWfzU2JPA6C4ooz2Sipt1TAaA9cF5R5NKHrCJdz7S0QWB74fEcAQa/gKtVXco30lCbAlC6TIZSH6PKFRY+qdG7598NHGb/LPkvMy0jVVK5mR8AKuPIZmGDTV0TGfLimdL8QS7l0EKy1acNdsFPv0IZclby91ABfqEapeqwUX38= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773678742; c=relaxed/simple; bh=VEWzjWkFJkvivdxzozBb+TjD4Z2NHTQj8mjnk16uEwg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GGqAztww7MQs6IAXXFm+01wITYYKxYs7UYVJ/SyNQg0hTMe6d5TSZ3wqQR7ADEJboR6Zti7veckrDVtNEq9eKb/Q1oqP0d9kjEqYOHR/UjCHlMhkuUclXeiqEEQI7AozF3ndnYA8g7cHKEaCpPuxCbmfTNoKxlOZot7wf1PEgTw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=q8TCCGfb; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="q8TCCGfb" Received: from killaraus.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id D7FDCB1A; Mon, 16 Mar 2026 17:31:06 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1773678667; bh=VEWzjWkFJkvivdxzozBb+TjD4Z2NHTQj8mjnk16uEwg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=q8TCCGfbSVarEprvUIY784Y6vJRSh26EoCv98Fy15dw78xwgxX4lMY76EHkJKEx4G Xwaf5H8gdPxcfNUot446XQVG7cR4Xtb5DHZU5lgDyeOmiCtLtygFRHGpskKS8WNWnD vJGfIRulunUJ533ll/eTI365rzUHoAhBqUDjnPzc= Date: Mon, 16 Mar 2026 18:32:16 +0200 From: Laurent Pinchart To: Maxime Ripard Cc: Maarten Lankhorst , Thomas Zimmermann , David Airlie , Simona Vetter , Jonathan Corbet , Shuah Khan , Dmitry Baryshkov , Jyri Sarha , Tomi Valkeinen , Andrzej Hajda , Neil Armstrong , Robert Foss , Jonas Karlman , Jernej Skrabec , dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 08/14] drm/mode-config: Create drm_mode_config_create_state() Message-ID: <20260316163216.GM31604@killaraus.ideasonboard.com> References: <20260310-drm-mode-config-init-v1-0-de7397c8e1cf@kernel.org> <20260310-drm-mode-config-init-v1-8-de7397c8e1cf@kernel.org> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260310-drm-mode-config-init-v1-8-de7397c8e1cf@kernel.org> On Tue, Mar 10, 2026 at 05:07:00PM +0100, Maxime Ripard wrote: > drm_mode_config_reset() can be used to create the initial state, but > also to return to the initial state, when doing a suspend/resume cycle > for example. > > It also affects both the software and the hardware, and drivers can > either choose to reset the hardware as well. Most will just create an "either" requires an "or". > empty state and the synchronisation between hardware and software states > will effectively be done when the first commit is done. > > That dual role can be harmful, since some objects do need to be > initialized but also need to be preserved across a suspend/resume cycle. > drm_private_obj are such objects for example. > > Thus, let's create another helper for drivers to call to initialize > their state when the driver is loaded, so we can make > drm_mode_config_reset() only about handling suspend/resume and similar. Does that mean that the state initialization at probe time from the hardware state is planned to be handled by .atomic_create_state() ? > Signed-off-by: Maxime Ripard > --- > drivers/gpu/drm/drm_atomic.c | 12 +++++- > drivers/gpu/drm/drm_mode_config.c | 83 +++++++++++++++++++++++++++++++++++++++ > include/drm/drm_mode_config.h | 1 + > 3 files changed, 94 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c > index 92c6afc8f22c8307a59dc266aacdb8e03351409d..d1885f895cce78725419b6291f4dbe5563e3b240 100644 > --- a/drivers/gpu/drm/drm_atomic.c > +++ b/drivers/gpu/drm/drm_atomic.c > @@ -58,12 +58,20 @@ > * checking or doing the update, while object states are allocated while > * the state will be, or is active in the hardware. > * > * Their respective lifetimes are: > * > - * - at reset time, the object reset implementation will allocate a new, > - * default, state and will store it in the object state pointer. > + * - at driver initialization time, the driver will allocate an initial, > + * pristine, state and will store it using > + * drm_mode_config_create_state(). Historically, this was one of > + * drm_mode_config_reset() job, so one might still encounter it in a > + * driver. Do you have plans to port drivers to the new API, to drop this last sentence sooner than later ? > + * > + * - at reset time, for example during suspend/resume, > + * drm_mode_config_reset() will reset the software and hardware state > + * to a known default and will store it in the object state pointer. > + * Not all objects are affected by drm_mode_config_reset() though. I have a bit of trouble understanding the design. How can drm_mode_config_reset() decide which objects should have their state reset (i.e. all objects but private objects in the current implementation), shouldn't that be a driver decision ? > * > * - whenever a new update is needed: > * > * + we allocate a new &struct drm_atomic_state using drm_atomic_state_alloc(). > * > diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c > index 95759a4b5176ff17032a9a267ec9de6980be0abc..1a84ac063d381014eb8afd7116e1e8b7a8fc92ca 100644 > --- a/drivers/gpu/drm/drm_mode_config.c > +++ b/drivers/gpu/drm/drm_mode_config.c > @@ -21,10 +21,11 @@ > */ > > #include > #include > > +#include > #include > #include > #include > #include > #include > @@ -278,10 +279,92 @@ void drm_mode_config_reset(struct drm_device *dev) > drm_mode_config_connector_create_state(connector); > drm_connector_list_iter_end(&conn_iter); > } > EXPORT_SYMBOL(drm_mode_config_reset); > > +/** > + * drm_mode_config_create_state - Allocates the initial state > + * @dev: drm device > + * > + * This functions creates the initial state for all the objects. Drivers > + * can use this in e.g. their driver load to initialize its software I think you meant s/its/their/ > + * state. > + * > + * It has two main differences with drm_mode_config_reset(): the reset() > + * hooks aren't called and thus the hardware will be left untouched, but > + * also the @drm_private_obj structures will be initialized as opposed > + * to drm_mode_config_reset() that skips them. > + * > + * Returns: 0 on success, negative error value on failure. > + */ > +int drm_mode_config_create_state(struct drm_device *dev) > +{ > + struct drm_crtc *crtc; > + struct drm_colorop *colorop; > + struct drm_plane *plane; > + struct drm_connector *connector; > + struct drm_connector_list_iter conn_iter; > + struct drm_private_obj *privobj; > + int ret; > + > + drm_for_each_privobj(privobj, dev) { > + struct drm_private_state *privobj_state; > + > + if (privobj->state) > + continue; > + > + if (!privobj->funcs->atomic_create_state) > + continue; > + > + privobj_state = privobj->funcs->atomic_create_state(privobj); > + if (IS_ERR(privobj_state)) > + return PTR_ERR(privobj_state); > + > + privobj->state = privobj_state; Either a helper function is missing, or you forgot to call it. > + } > + > + drm_for_each_colorop(colorop, dev) { > + if (colorop->state) > + continue; > + > + // TODO: Implement atomic_create_state for colorop. Oops :-) > + drm_colorop_reset(colorop); > + } > + > + drm_for_each_plane(plane, dev) { > + if (plane->state) > + continue; > + > + ret = drm_mode_config_plane_create_state(plane); > + if (ret) > + return ret; > + } > + > + drm_for_each_crtc(crtc, dev) { > + if (crtc->state) > + continue; > + > + ret = drm_mode_config_crtc_create_state(crtc); > + if (ret) > + return ret; > + } > + > + drm_connector_list_iter_begin(dev, &conn_iter); > + drm_for_each_connector_iter(connector, &conn_iter) { > + if (connector->state) > + continue; > + > + ret = drm_mode_config_connector_create_state(connector); > + if (ret) > + return ret; > + } > + drm_connector_list_iter_end(&conn_iter); > + > + return 0; > +} > +EXPORT_SYMBOL(drm_mode_config_create_state); > + > /* > * Global properties > */ > static const struct drm_prop_enum_list drm_plane_type_enum_list[] = { > { DRM_PLANE_TYPE_OVERLAY, "Overlay" }, > diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h > index 5e1dd0cfccde2d2bc00a09e98e4adc65833dad08..428ae75b7c4f193dfbd49c15a2f2ef32209a6cef 100644 > --- a/include/drm/drm_mode_config.h > +++ b/include/drm/drm_mode_config.h > @@ -1000,9 +1000,10 @@ int __must_check drmm_mode_config_init(struct drm_device *dev); > static inline int drm_mode_config_init(struct drm_device *dev) > { > return drmm_mode_config_init(dev); > } > > +int drm_mode_config_create_state(struct drm_device *dev); > void drm_mode_config_reset(struct drm_device *dev); > void drm_mode_config_cleanup(struct drm_device *dev); > > #endif > -- Regards, Laurent Pinchart