From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5A0AFF885A for ; Mon, 4 May 2026 16:52:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=+cMkB9Pn+PhAlTlbMNpdaARg3YuqZ1ZGJc9cJ63qou8=; b=XFy5jKoc2PSLjv85M8mj3kHAos hsUm3bFV/Y7seBECxkjCXNMtBnEhvZJEUC8ArjzOkqfnWgewYTwmFU4fvygncE4sC8MEmfG354NoY GJc2kkaZkncKKqAplPFyOYRdbdOFQdZzX4iQvkJ8SMZCwPiS0059sCvbEhuk9R83EXP0YlDljynhe acPIJkTIhMuK3C5qX1PNTY0kDJOBYw3F6E3WGk76aZinX71d8/xRYQ6WO4vguJZmmDrcnyJDDrqL0 Uezb8oHFi7Z+f8lAYwqhLUfd+hUmdJRARmwe+yATgAicMF5y8acV2sQgmnpmwVYvSwtc8sNCGqwtr wfFvQO4w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wJwX4-0000000DlOM-3ptp; Mon, 04 May 2026 16:52:34 +0000 Received: from perceval.ideasonboard.com ([213.167.242.64]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wJwX2-0000000DlLv-11Dp for linux-arm-kernel@lists.infradead.org; Mon, 04 May 2026 16:52:33 +0000 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 ESMTPSA id 4F3B79C; Mon, 4 May 2026 18:52:28 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1777913548; bh=Zp02atCQOj7Mvz8FpD9o1Rib3JYiNwqY/fzhTQloymc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=apQMfJezBXKACeI7uQn/oz/Lcn5MEWfk1oZq+4/QwXjK4nd490DgyWBu45eZIV78V oG6cukUKj4q26+bcvBlCyV4+vCJ07TZ41wfzmQ93Z73XT8XzHkRyqZY1OXQuMthKKo Uy+VcIEaS1+FAh3h5pLW3a03re+ils9QLAHjOAl8= Date: Mon, 4 May 2026 19:52:29 +0300 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 , Simon Ser , Harry Wentland , Melissa Wen , Sebastian Wick , Alex Hung , Jani Nikula , Rodrigo Vivi , Joonas Lahtinen , Tvrtko Ursulin , Chen-Yu Tsai , Samuel Holland , Dave Stevenson , =?utf-8?B?TWHDrXJh?= Canal , Raspberry Pi Kernel Maintenance , dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Daniel Stone , intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev Subject: Re: [PATCH v3 10/20] drm/plane: Add new atomic_create_state callback Message-ID: <20260504165229.GM1344263@killaraus.ideasonboard.com> References: <20260424-drm-mode-config-init-v3-0-8b68d9db0d8b@kernel.org> <20260424-drm-mode-config-init-v3-10-8b68d9db0d8b@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260424-drm-mode-config-init-v3-10-8b68d9db0d8b@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260504_095232_427845_A5747826 X-CRM114-Status: GOOD ( 36.64 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Maxime, Thank you for the patch. On Fri, Apr 24, 2026 at 12:18:50PM +0200, Maxime Ripard wrote: > Commit 47b5ac7daa46 ("drm/atomic: Add new atomic_create_state callback > to drm_private_obj") introduced a new pattern for allocating drm object > states. > > Instead of relying on the reset() callback, it created a new > atomic_create_state hook. This is helpful because reset is a bit > overloaded: it's used to create the initial software state, reset it, > but also reset the hardware. > > It can also be used either at probe time, to create the initial state > and possibly reset the hardware to an expected default, but also during > suspend/resume. > > Both these cases come with different expectations too: during the > initialization, we want to initialize all states, but during > suspend/resume, drm_private_states for example are expected to be kept > around. > > reset() also isn't fallible, which makes it harder to handle > initialization errors properly. This is only really relevant for some > drivers though, since all the helpers for reset only create a new > state, and don't touch the hardware at all. > > It was thus decided to create a new hook that would allocate and > initialize a pristine state without any side effect: > atomic_create_state to untangle a bit some of it, and to separate the > initialization with the actual reset one might need during a > suspend/resume. > > Continue the transition to the new pattern with planes. > > Signed-off-by: Maxime Ripard > --- > drivers/gpu/drm/drm_atomic_state_helper.c | 25 +++++++++++++++++++++++++ > drivers/gpu/drm/drm_mode_config.c | 21 ++++++++++++++++++++- > include/drm/drm_atomic_state_helper.h | 2 ++ > include/drm/drm_plane.h | 16 ++++++++++++++++ > 4 files changed, 63 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c > index 285efbf29520..50fe4eec41a8 100644 > --- a/drivers/gpu/drm/drm_atomic_state_helper.c > +++ b/drivers/gpu/drm/drm_atomic_state_helper.c > @@ -338,10 +338,35 @@ void drm_atomic_helper_plane_reset(struct drm_plane *plane) > if (plane->state) > __drm_atomic_helper_plane_reset(plane, plane->state); > } > EXPORT_SYMBOL(drm_atomic_helper_plane_reset); > > +/** > + * drm_atomic_helper_plane_create_state - default &drm_plane_funcs.atomic_create_state hook for planes drm_atomic_helper_colorop_create_state() states "Allocates and initializes colorop atomic state", while here you document it as "default hook for planes". Consistency would be good. > + * @plane: plane object > + * > + * Initializes a pristine @drm_plane_state. "Allocate and initialize ..." > + * > + * This is useful for drivers that don't subclass @drm_plane_state. > + * > + * RETURNS: > + * Pointer to new plane state, or ERR_PTR on failure. > + */ > +struct drm_plane_state *drm_atomic_helper_plane_create_state(struct drm_plane *plane) > +{ > + struct drm_plane_state *state; > + > + state = kzalloc_obj(*state); > + if (!state) > + return ERR_PTR(-ENOMEM); > + > + __drm_atomic_helper_plane_state_init(state, plane); > + > + return state; > +} > +EXPORT_SYMBOL(drm_atomic_helper_plane_create_state); > + > /** > * __drm_atomic_helper_plane_duplicate_state - copy atomic plane state > * @plane: plane object > * @state: atomic plane state > * > diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c > index c33382a38191..10b7815cbe48 100644 > --- a/drivers/gpu/drm/drm_mode_config.c > +++ b/drivers/gpu/drm/drm_mode_config.c > @@ -180,10 +180,26 @@ int drm_mode_getresources(struct drm_device *dev, void *data, > drm_connector_list_iter_end(&conn_iter); > > return ret; > } > > +static int drm_mode_config_plane_create_state(struct drm_plane *plane) > +{ > + struct drm_plane_state *plane_state; > + > + if (!plane->funcs->atomic_create_state) > + return 0; > + > + plane_state = plane->funcs->atomic_create_state(plane); > + if (IS_ERR(plane_state)) > + return PTR_ERR(plane_state); > + > + plane->state = plane_state; > + > + return 0; > +} > + > /** > * drm_mode_config_reset - call ->reset callbacks > * @dev: drm device > * > * This functions calls all the crtc's, encoder's and connector's ->reset > @@ -204,13 +220,16 @@ void drm_mode_config_reset(struct drm_device *dev) > struct drm_connector_list_iter conn_iter; > > drm_for_each_colorop(colorop, dev) > drm_colorop_reset(colorop); > > - drm_for_each_plane(plane, dev) > + drm_for_each_plane(plane, dev) { > if (plane->funcs->reset) > plane->funcs->reset(plane); > + else if (plane->funcs->atomic_create_state) > + drm_mode_config_plane_create_state(plane); > + } > > drm_for_each_crtc(crtc, dev) > if (crtc->funcs->reset) > crtc->funcs->reset(crtc); > > diff --git a/include/drm/drm_atomic_state_helper.h b/include/drm/drm_atomic_state_helper.h > index 44e8850aae7f..df371b2eef3e 100644 > --- a/include/drm/drm_atomic_state_helper.h > +++ b/include/drm/drm_atomic_state_helper.h > @@ -53,10 +53,12 @@ void __drm_atomic_helper_crtc_destroy_state(struct drm_crtc_state *state); > void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc, > struct drm_crtc_state *state); > > void __drm_atomic_helper_plane_state_init(struct drm_plane_state *state, > struct drm_plane *plane); > +struct drm_plane_state * > +drm_atomic_helper_plane_create_state(struct drm_plane *plane); > void __drm_atomic_helper_plane_reset(struct drm_plane *plane, > struct drm_plane_state *state); > void drm_atomic_helper_plane_reset(struct drm_plane *plane); > void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane, > struct drm_plane_state *state); > diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h > index 703ef4d1bbbc..886e219c4609 100644 > --- a/include/drm/drm_plane.h > +++ b/include/drm/drm_plane.h > @@ -386,10 +386,26 @@ struct drm_plane_funcs { > * 0 on success or a negative error code on failure. > */ > int (*set_property)(struct drm_plane *plane, > struct drm_property *property, uint64_t val); > > + /** > + * @atomic_create_state: > + * > + * Allocates a pristine, initialized, state for the plane object s/Allocates/Allocate/ based on the documentation of other callbacks, and the fact that imperative style is the usual standard in kernel documentation. Reviewed-by: Laurent Pinchart > + * and returns it. This callback must have no side effects: in > + * particular, the returned state must not be assigned to the > + * object's state pointer and it must not affect the hardware > + * state. > + * > + * RETURNS: > + * > + * A new, pristine, plane state instance or an error pointer > + * on failure. > + */ > + struct drm_plane_state *(*atomic_create_state)(struct drm_plane *plane); > + > /** > * @atomic_duplicate_state: > * > * Duplicate the current atomic state for this plane and return it. > * The core and helpers guarantee that any atomic state duplicated with -- Regards, Laurent Pinchart