From patchwork Mon Aug 26 12:41:04 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 13777812 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 0A9AD188584; Mon, 26 Aug 2024 12:41:21 +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=1724676082; cv=none; b=iwMKDjFQf808W29Jr8l95ypH68d9uJ9XGTFLG/5L7ATQ1Kphe0fMWcsYyPQ19jRzCHcK4Tgk06925qY90gpspSO71oGtxL90FtoHSOEdGP7KzviHa2HTNc2W3yuus46UOvikbqtgzkjzcL4X51/zgc6kyTu7+pr+SRLLS6ljW2M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724676082; c=relaxed/simple; bh=SxMIqFS6SWymda0VHG0xFKm6S+RPDfcEs0E4NjlsKD0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=C5Y4y7pFTYF1PljR/NHZUxIuZpdSlu0jzACgnxt+Q0Evy/mXLUhTp2uZsLF4Zm1NRAD+9oycGr69ffZXpzgOlM7No4fTnsOnfCmM+t7e+0o0OT8Vnyb7fXj8zzjfUWVePCpjHn7NKwc2zBz5QoClURAN9RcINSm/AIDZvh0hMm4= 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=RlRqrv7n; 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="RlRqrv7n" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 4BC2F6CA; Mon, 26 Aug 2024 14:40:12 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1724676012; bh=SxMIqFS6SWymda0VHG0xFKm6S+RPDfcEs0E4NjlsKD0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RlRqrv7nlQaxNIJUjtfhEXyYX30OsyqP8/MHyN0aBwMymy/7hJqki2+NrZ/LPKOfv eWVd+DcOb6w+ie+qhyOuJ5xblIohyVNj+8HngHv+Lrz0xUA/J8Sbbz18cl5OcZaPXj bzyZ5r8uBpLCT5eNJLxQN8NN18F4kwtuWOkTJK+E= From: Laurent Pinchart To: linux-media@vger.kernel.org Cc: Chen-Yu Tsai , Eugen Hristev , Hans Verkuil , Jacopo Mondi , Kieran Bingham , Maxime Ripard , Sakari Ailus , Tomi Valkeinen , linux-renesas-soc@vger.kernel.org, linux-sunxi@lists.linux.dev Subject: [PATCH v3 5/7] media: v4l2-subdev: Support hybrid links in v4l2_subdev_link_validate() Date: Mon, 26 Aug 2024 15:41:04 +0300 Message-ID: <20240826124106.3823-6-laurent.pinchart+renesas@ideasonboard.com> X-Mailer: git-send-email 2.44.2 In-Reply-To: <20240826124106.3823-1-laurent.pinchart+renesas@ideasonboard.com> References: <20240826124106.3823-1-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 The v4l2_subdev_link_validate() helper function is meant to be used as a drop-in implementation of a V4L2 subdev entity .link_validate() handler. It supports subdev-to-subdev links only, and complains if one end of the link is not a subdev. This forces drivers that have video output devices connected to subdevs to implement a custom .link_validate() handler, calling v4l2_subdev_link_validate() for the subdev-to-subdev links, and performing manual link validation for the video-to-subdev links. Video devices embed a media entity, and therefore also have a .link_validate() operation. For video capture devices, the operation should be manually implemented by drivers for validate the subdev-to-video links. For video output devices, on the other hand, that operation is never called, as link validation is performed in the context of the sink entity. As a result, we end up forcing drivers to implement a custom .link_validate() handler for subdevs connected to video output devices, when the video devices provide an operation that could be used for that purpose. To improve that situation, make v4l2_subdev_link_validate() delegate link validation to the source's .link_validate() operation when the link source is a video device and the link sink is a subdev. This allows broader usage of v4l2_subdev_link_validate(), and simplifies drivers by making video device link validation easy to implement in the video device .link_validate(), regardless of whether the video device is an output device or a capture device. Signed-off-by: Laurent Pinchart --- Changes since v2: - Expand comment about infinite loops --- drivers/media/v4l2-core/v4l2-subdev.c | 43 +++++++++++++++++++++++---- include/media/v4l2-subdev.h | 6 ++++ 2 files changed, 44 insertions(+), 5 deletions(-) diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c index d3196042d5c5..3a4ba08810d2 100644 --- a/drivers/media/v4l2-core/v4l2-subdev.c +++ b/drivers/media/v4l2-core/v4l2-subdev.c @@ -1450,13 +1450,46 @@ int v4l2_subdev_link_validate(struct media_link *link) if (WARN_ON_ONCE(!is_media_entity_v4l2_subdev(link->sink->entity))) return -EINVAL; - if (!is_media_entity_v4l2_subdev(link->source->entity)) { - pr_warn_once("source of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", - link->source->entity->name, link->source->index, - link->sink->entity->name, link->sink->index); - return 0; + /* + * If the source is a video device, delegate link validation to it. This + * allows usage of this helper for subdev connected to a video output + * device, provided that the driver implement the video output device's + * .link_validate() operation. + */ + if (is_media_entity_v4l2_video_device(link->source->entity)) { + struct media_entity *source = link->source->entity; + + if (!source->ops || !source->ops->link_validate) { + /* + * Many existing drivers do not implement the required + * .link_validate() operation for their video devices. + * Print a warning to get the drivers fixed, and return + * 0 to avoid breaking userspace. This should + * eventually be turned into a WARN_ON() when all + * drivers will have been fixed. + */ + pr_warn_once("video device '%s' does not implement .link_validate(), driver bug!\n", + source->name); + return 0; + } + + /* + * Avoid infinite loops in case a video device incorrectly uses + * this helper function as its .link_validate() handler. + */ + if (WARN_ON(source->ops->link_validate == v4l2_subdev_link_validate)) + return -EINVAL; + + return source->ops->link_validate(link); } + /* + * If the source is still not a subdev, usage of this helper is a clear + * driver bug. + */ + if (WARN_ON(!is_media_entity_v4l2_subdev(link->source->entity))) + return -EINVAL; + sink_sd = media_entity_to_v4l2_subdev(link->sink->entity); source_sd = media_entity_to_v4l2_subdev(link->source->entity); diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h index bd235d325ff9..8daa0929865c 100644 --- a/include/media/v4l2-subdev.h +++ b/include/media/v4l2-subdev.h @@ -1250,6 +1250,12 @@ int v4l2_subdev_link_validate_default(struct v4l2_subdev *sd, * calls v4l2_subdev_link_validate_default() to ensure that * width, height and the media bus pixel code are equal on both * source and sink of the link. + * + * The function can be used as a drop-in &media_entity_ops.link_validate + * implementation for v4l2_subdev instances. It supports all links between + * subdevs, as well as links between subdevs and video devices, provided that + * the video devices also implement their &media_entity_ops.link_validate + * operation. */ int v4l2_subdev_link_validate(struct media_link *link);