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{ "id": 3405, "url": "https://patchwork.libcamera.org/api/covers/3405/?format=api", "web_url": "https://patchwork.libcamera.org/cover/3405/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/projects/1/?format=api", "name": "libcamera", "link_name": "libcamera", "list_id": "libcamera_core", "list_email": "libcamera-devel@lists.libcamera.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20200407152157.1686474-1-jacopo@jmondi.org>", "date": "2020-04-07T15:21:54", "name": "[libcamera-devel,v3,0/3] media: Register read-only sub-dev devnode", "submitter": { "id": 3, "url": "https://patchwork.libcamera.org/api/people/3/?format=api", "name": "Jacopo Mondi", "email": "jacopo@jmondi.org" }, "mbox": "https://patchwork.libcamera.org/cover/3405/mbox/", "series": [ { "id": 800, "url": "https://patchwork.libcamera.org/api/series/800/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=800", "date": "2020-04-07T15:21:54", "name": "media: Register read-only sub-dev devnode", "version": 3, "mbox": "https://patchwork.libcamera.org/series/800/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/covers/3405/comments/", "headers": { "Return-Path": "<jacopo@jmondi.org>", "Received": [ "from relay9-d.mail.gandi.net (relay9-d.mail.gandi.net\n\t[217.70.183.199])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 1F35F600F0\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tTue, 7 Apr 2020 17:19:05 +0200 (CEST)", "from localhost.localdomain (2-224-242-101.ip172.fastwebnet.it\n\t[2.224.242.101]) (Authenticated sender: jacopo@jmondi.org)\n\tby relay9-d.mail.gandi.net (Postfix) with ESMTPSA id B686DFF809;\n\tTue, 7 Apr 2020 15:19:02 +0000 (UTC)" ], "X-Originating-IP": "2.224.242.101", "From": "Jacopo Mondi <jacopo@jmondi.org>", "To": "linux-media@vger.kernel.org,\n\tlibcamera-devel@lists.libcamera.org", "Cc": "Jacopo Mondi <jacopo@jmondi.org>, mchehab@kernel.org,\n\thverkuil-cisco@xs4all.nl, sakari.ailus@linux.intel.com,\n\tandrey.konovalov@linaro.org, laurent.pinchart@ideasonboard.com", "Date": "Tue, 7 Apr 2020 17:21:54 +0200", "Message-Id": "<20200407152157.1686474-1-jacopo@jmondi.org>", "X-Mailer": "git-send-email 2.26.0", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Subject": "[libcamera-devel] [PATCH v3 0/3] media: Register read-only sub-dev\n\tdevnode", "X-BeenThere": "libcamera-devel@lists.libcamera.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "<libcamera-devel.lists.libcamera.org>", "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>", "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>", "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>", "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>", "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>", "X-List-Received-Date": "Tue, 07 Apr 2020 15:19:05 -0000" }, "content": "Add new function v4l2_device_register_ro_subdev_nodes() to pair with\nv4l2_device_register_subdev_nodes() that allows a bridge driver to register the\ndevice node for its subdevices in read-only mode.\n\nDevnode-centric (aka non-MC) bridge drivers control their subdevices through\ndirect calls to v4l2 subdev operations and do not want userspace to be able\nto control the subdevice configuration by calling ioctls on the sub-device\ndevnode. For this reason, they usually refrain from registering any devnode at\nall for their subdevices.\n\nHowever it is sometimes required for userspace to access the sub-dev device\nnodes to collect information on the actual configuration, without changing\nthe one currently applied to the device.\n\nThis requirement became pressing while working on libcamera on devnode-centric\nplatforms that do not expose any sub-device for their camera sensor to prevent\nuserspace from changing their configuration. To allow them to register device\nnode and being guaranteed to retain control of the subdevice configuration this\nseries proposes a way to register device nodes in read-only to restrict\naccess to all ioctls that could potentially affect the sub-dev configuration.\n\nThanks\n j\n\nv2->v3:\n- Add Sakari's ack to the series\n- Documentation:\n - Address Sakari' and Hans suggestions\n- Implementation:\n - Rename V4L2_FL_RO_DEVNODE to V4L2_FL_SUBDEV_RO_DEVNODE\n - Limit the ability to register sub-device video device nodes to\n driver claiming support for CONFIG_VIDEO_V4L2_SUBDEV_API\n\nv1->v2:\n- Documentation:\n - Add a new patch using Laurent's suggestion to update the sub-device\n userspace API introduction\n - Take in some of Laurent's suggestions in v4l2-subdev.rst and add a new\n section in dev-subdev.rst\n- Implementation:\n - As noted by Andrey, V4L2_FL_* are meant to be used as bitmasks. Use\n test_bit()/set_bit() as the rest of the v4l2 core does. It's a bit an\n overkill compared to use plain BIT() as noted by Sakari but I preferred\n consistency with the rest of the core\n - Make v4l2_device_register_subdev_nodes() and\n v4l2_device_register_ro_subdev_nodes() to v4l2-device.h and make them\n inline functions. Documentation style has been copied from other functions\n with similar implementations, such as __video_register_device() in\n v4l2-dev.h\n\nJacopo Mondi (3):\n Documentation: media: Update sub-device API intro\n Documentation: media: Document read-only subdevice\n media: v4l2-dev: Add v4l2_device_register_ro_subdev_node()\n\n Documentation/media/kapi/v4l2-subdev.rst | 53 ++++++++++++++++++-\n Documentation/media/uapi/v4l/dev-subdev.rst | 5 ++\n .../media/uapi/v4l/vidioc-g-dv-timings.rst | 6 +++\n Documentation/media/uapi/v4l/vidioc-g-std.rst | 6 +++\n .../media/uapi/v4l/vidioc-subdev-g-crop.rst | 9 ++++\n .../media/uapi/v4l/vidioc-subdev-g-fmt.rst | 8 +++\n .../v4l/vidioc-subdev-g-frame-interval.rst | 8 +++\n .../uapi/v4l/vidioc-subdev-g-selection.rst | 8 +++\n drivers/media/v4l2-core/v4l2-device.c | 7 ++-\n drivers/media/v4l2-core/v4l2-subdev.c | 19 +++++++\n include/media/v4l2-dev.h | 7 +++\n include/media/v4l2-device.h | 50 +++++++++++++++--\n 12 files changed, 178 insertions(+), 8 deletions(-)\n\n--\n2.26.0" }