From patchwork Tue May 7 06:03:22 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 13656294 X-Patchwork-Delegate: kieran@bingham.xyz 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 E4F906BFD5; Tue, 7 May 2024 06:03:34 +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=1715061817; cv=none; b=jXuTkncYc3ysrZjtjNqcXo60AXwkJT/5GqJox+ZrN0zIwqIdnKt11wI9P9jt2n9nxnMQ4uCyQ1iXmNIjsoBnbstUM7cgRCDEjATCzFQJNpdaIACrUpoMW0w5T6xo0ovqjYLQnBP894Fr9lok1SWo5XDYYejPFRakURk6n9y4dvw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715061817; c=relaxed/simple; bh=CAfZBviyEOgNMqsGAM9sVQjH0LaJVid1J1G79UQlAb4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZNc7+e72xv1kfCHSfhsu7LVz/nOay7Gi2svRFQfZoC5QnPT8Ep5FTGm5gSFTtg9sbxDLlDR0jMnn8zq4VGGiNXHUCCVGWxxW2Je14+pyULLy5htwk1KG5R7QngYFSVSpk4B/mfoCDKKxbz2oszmvcRHx5fQaHQYli3+vKJNVQy4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (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=UnNNn23e; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="UnNNn23e" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 101ABA98; Tue, 7 May 2024 08:03:31 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1715061811; bh=CAfZBviyEOgNMqsGAM9sVQjH0LaJVid1J1G79UQlAb4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UnNNn23ezDwfKmjV52iKAmgE72r7W2zhEZII5A/1ySGgNqm8MCuW9aXm+vypdzqcO 3Nvw2nKQYkQ82bPlvD7M2YxOjoG6cQmPnM2ClldQJNYZlfAZ0gZjxmMsJHfPKGBekz d/vVpA2Mqbuo3b0uxVqGtLSAZD6CMQZe8h95esLQ= From: Laurent Pinchart To: linux-media@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org, Sakari Ailus , Tomi Valkeinen , Hans Verkuil , Dafna Hirschfeld , linux-rockchip@lists.infradead.org Subject: [PATCH v2 1/2] media: v4l2-subdev: Provide const-aware subdev state accessors Date: Tue, 7 May 2024 09:03:22 +0300 Message-ID: <20240507060323.26950-2-laurent.pinchart+renesas@ideasonboard.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240507060323.26950-1-laurent.pinchart+renesas@ideasonboard.com> References: <20240507060323.26950-1-laurent.pinchart+renesas@ideasonboard.com> Precedence: bulk X-Mailing-List: linux-renesas-soc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 It would be useful to mark instances of v4l2_subdev_state structures as const when code needs to access them read-only. This isn't currently possible, as the v4l2_subdev_state_get_*() accessor functions take a non-const pointer to the state. Use _Generic() to provide two different versions of the accessors, for const and non-const states respectively. The former returns a const pointer to the requested format, rectangle or interval, implementing const-correctness. The latter returns a non-const pointer, preserving the current behaviour for drivers. Signed-off-by: Laurent Pinchart --- Changes since v1: - Wrap the accessors with _Generic() using a single macro instead of adding a _Generic() statement in each of them. --- include/media/v4l2-subdev.h | 40 +++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 13 deletions(-) diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h index e30c463d90e5..c8cfa1eaa82f 100644 --- a/include/media/v4l2-subdev.h +++ b/include/media/v4l2-subdev.h @@ -1326,6 +1326,16 @@ void v4l2_subdev_cleanup(struct v4l2_subdev *sd); #define __v4l2_subdev_state_gen_call(NAME, _1, ARG, ...) \ __v4l2_subdev_state_get_ ## NAME ## ARG +/* + * A macro to constify the return value of the state accessors when the state + * parameter is const. + */ +#define __v4l2_subdev_state_constify_call(state, value) \ + _Generic(state, \ + const typeof(*(state)) *: (const typeof(value))value, \ + default: value \ + ) + /** * v4l2_subdev_state_get_format() - Get pointer to a stream format * @state: subdevice state @@ -1340,16 +1350,17 @@ void v4l2_subdev_cleanup(struct v4l2_subdev *sd); */ /* * Wrap v4l2_subdev_state_get_format(), allowing the function to be called with - * two or three arguments. The purpose of the __v4l2_subdev_state_get_format() + * two or three arguments. The purpose of the __v4l2_subdev_state_gen_call() * macro below is to come up with the name of the function or macro to call, * using the last two arguments (_stream and _pad). The selected function or * macro is then called using the arguments specified by the caller. A similar * arrangement is used for v4l2_subdev_state_crop() and * v4l2_subdev_state_compose() below. */ -#define v4l2_subdev_state_get_format(state, pad, ...) \ - __v4l2_subdev_state_gen_call(format, ##__VA_ARGS__, , _pad) \ - (state, pad, ##__VA_ARGS__) +#define v4l2_subdev_state_get_format(state, pad, ...) \ + __v4l2_subdev_state_constify_call(state, \ + __v4l2_subdev_state_gen_call(format, ##__VA_ARGS__, , _pad) \ + ((struct v4l2_subdev_state *)state, pad, ##__VA_ARGS__)) #define __v4l2_subdev_state_get_format_pad(state, pad) \ __v4l2_subdev_state_get_format(state, pad, 0) struct v4l2_mbus_framefmt * @@ -1368,9 +1379,10 @@ __v4l2_subdev_state_get_format(struct v4l2_subdev_state *state, * For stream-unaware drivers the crop rectangle for the corresponding pad is * returned. If the pad does not exist, NULL is returned. */ -#define v4l2_subdev_state_get_crop(state, pad, ...) \ - __v4l2_subdev_state_gen_call(crop, ##__VA_ARGS__, , _pad) \ - (state, pad, ##__VA_ARGS__) +#define v4l2_subdev_state_get_crop(state, pad, ...) \ + __v4l2_subdev_state_constify_call(state, \ + __v4l2_subdev_state_gen_call(crop, ##__VA_ARGS__, , _pad) \ + ((struct v4l2_subdev_state *)state, pad, ##__VA_ARGS__)) #define __v4l2_subdev_state_get_crop_pad(state, pad) \ __v4l2_subdev_state_get_crop(state, pad, 0) struct v4l2_rect * @@ -1389,9 +1401,10 @@ __v4l2_subdev_state_get_crop(struct v4l2_subdev_state *state, unsigned int pad, * For stream-unaware drivers the compose rectangle for the corresponding pad is * returned. If the pad does not exist, NULL is returned. */ -#define v4l2_subdev_state_get_compose(state, pad, ...) \ - __v4l2_subdev_state_gen_call(compose, ##__VA_ARGS__, , _pad) \ - (state, pad, ##__VA_ARGS__) +#define v4l2_subdev_state_get_compose(state, pad, ...) \ + __v4l2_subdev_state_constify_call(state, \ + __v4l2_subdev_state_gen_call(compose, ##__VA_ARGS__, , _pad) \ + ((struct v4l2_subdev_state *)state, pad, ##__VA_ARGS__)) #define __v4l2_subdev_state_get_compose_pad(state, pad) \ __v4l2_subdev_state_get_compose(state, pad, 0) struct v4l2_rect * @@ -1410,9 +1423,10 @@ __v4l2_subdev_state_get_compose(struct v4l2_subdev_state *state, * For stream-unaware drivers the frame interval for the corresponding pad is * returned. If the pad does not exist, NULL is returned. */ -#define v4l2_subdev_state_get_interval(state, pad, ...) \ - __v4l2_subdev_state_gen_call(interval, ##__VA_ARGS__, , _pad) \ - (state, pad, ##__VA_ARGS__) +#define v4l2_subdev_state_get_interval(state, pad, ...) \ + __v4l2_subdev_state_constify_call(state, \ + __v4l2_subdev_state_gen_call(interval, ##__VA_ARGS__, , _pad) \ + ((struct v4l2_subdev_state *)state, pad, ##__VA_ARGS__)) #define __v4l2_subdev_state_get_interval_pad(state, pad) \ __v4l2_subdev_state_get_interval(state, pad, 0) struct v4l2_fract *