From patchwork Thu Aug 22 15:35:20 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 20989 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id 780C4C323E for ; Thu, 22 Aug 2024 15:35:33 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id 839B1633D1; Thu, 22 Aug 2024 17:35:32 +0200 (CEST) Authentication-Results: lancelot.ideasonboard.com; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="sGOq2dDg"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id DBC9163369 for ; Thu, 22 Aug 2024 17:35:30 +0200 (CEST) Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 9C9BF899; Thu, 22 Aug 2024 17:34:26 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1724340866; bh=ynR/rlt2GTIBZ6UQWXHvIDOQFJGcuX9UXR6Ua9Iv6O8=; h=From:To:Cc:Subject:Date:From; b=sGOq2dDgB6V8mJ7SkGjZNeZtyNmsfo5V1Wjxl/UwNwGChBH+Eymh/N7V+QP48kg2H 7X3IZvn8oVJsC0fHCLCtQj73P3D0V6zYUsc/e6sq0+s3vwtI0PJBPbUV0T5m+8q7XL iKYX4JiLq01dmYQd36s/1/t7SOUa+740kD5ayegU= From: Laurent Pinchart To: libcamera-devel@lists.libcamera.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 v2 0/7] media: v4l2: Improve media link validation Date: Thu, 22 Aug 2024 18:35:20 +0300 Message-ID: <20240822153527.25320-1-laurent.pinchart+renesas@ideasonboard.com> X-Mailer: git-send-email 2.44.2 MIME-Version: 1.0 X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" Hello, This patch series improves the link validation helpers to make it easier for drivers to validate all links in a pipeline. The vast majority of drivers use the v4l2_subdev_link_validate() function as their .link_validate() handler for subdevs. This correctly validates subdev-to-subdev links. For links between subdevs and video capture devices, a few drivers implement the .link_validate() operation of their video devices, while others implement manual validation in their .streamon() handler, or don't implement validation at all. Links between video output devices are in an even worse state, as the link validation logic at pipeline start time does not call the .link_validate() operation on the source side of a link, leaving manual validation in .streamon() the only option. Adding insult to injury, v4l2_subdev_link_validate() prints a warning when the link's source is not a subdev, which forces drivers to implement a manual subdev link validation handler for subdevs connected to output video nodes. It turns out that v4l2_subdev_link_validate() is even used in the .link_validate() implementation of video devices by two drivers. This is clearly wrong, and is addressed by patches 1/7 to 3/7. Note that patch 3/7 should ideally implement real validation of the link between the subdev and video capture device, but that requires understanding of the driver's logic as well as testing, so I have left it out as an exercise for the driver's maintainer. The patch doesn't introduce any regression. Patch 4/7 then starts refactoring the v4l2_subdev_link_validate() to separate the current warning in two categories, with a WARN_ON() for an issue that indicates a clear driver bug (and does not occur in any driver in mainline at the moment), and keeping the pr_warn_once() for other issues that are present in multiple drivers. Patch 5/7 continues with expanding v4l2_subdev_link_validate() to better support links from video output devices to subdevs, delegating the validation to the video output device's .link_validate() operation. This allows using v4l2_subdev_link_validate() for all subdevs in a driver, regardless of whether they are connected to other subdevs, video capture devices or video output devices, and implementing all the link validation for video devices in their .link_validate() operation. Patches 6/7 and 7/7 then address the v4l2_subdev_link_validate() warning for the vsp1 driver. Patch 6/7 silences the warning. This is unfortunately done with a workaround, as the ideal implementation, moving all validation for video devices to their .link_validate() operation as showcased in patch 7/7, breaks operation of the vsp1 unit test suite. While that is fixable in the test suite, it indicates that other userspace applications may also break as a result. To my great sadness, I had to mark patch 7/7 as [DNI]. This does not make the v4l2_subdev_link_validate() improvements in patch 5/7 pointless, as they are useful for new drivers, as well as drivers that don't include multiple video devices in a pipeline. Laurent Pinchart (7): media: microchip-isc: Drop v4l2_subdev_link_validate() for video devices media: sun4i_csi: Implement link validate for sun4i_csi subdev media: sun4i_csi: Don't use v4l2_subdev_link_validate() for video device media: v4l2-subdev: Refactor warnings in v4l2_subdev_link_validate() media: v4l2-subdev: Support hybrid links in v4l2_subdev_link_validate() media: renesas: vsp1: Implement .link_validate() for video devices [DNI] media: renesas: vsp1: Validate all links through .link_validate() .../platform/microchip/microchip-isc-base.c | 19 +--- .../media/platform/renesas/vsp1/vsp1_video.c | 104 +++++++++--------- .../platform/sunxi/sun4i-csi/sun4i_csi.c | 12 ++ drivers/media/v4l2-core/v4l2-subdev.c | 50 +++++++-- include/media/v4l2-subdev.h | 6 + 5 files changed, 115 insertions(+), 76 deletions(-) base-commit: a043ea54bbb975ca9239c69fd17f430488d33522