Hi Sakari & all, On 16.04.2024 22:32, Sakari Ailus wrote:
Hi folks, Here are a few patches to add support generic, line based metadata as well as internal pads. While the amount of code is not very large, to the contrary it is quite small actually IMO, I presume what this is about and why it is being proposed requires some explaining. Metadata mbus codes and formats have existed for some time in V4L2. They however have been only used by drivers that produce the data itself and effectively this metadata has always been statistics of some sort (at least when it comes to ISPs). What is different here is that we intend to add support for metadata originating from camera sensors. Camera sensors produce different kinds of metadata, embedded data (usually register address--value pairs used to capture the frame, in a more or less sensor specific format), histograms (in a very sensor specific format), dark pixels etc. The number of these formats is probably going to be about as large as image data formats if not larger, as the image data formats are much better standardised but a smaller subset of them will be supported by V4L2, at least initially but possibly much more in the long run. Having this many device specific formats would be a major problem for all the other drivers along that pipeline (not to mention the users of those drivers), including bridge (e.g. CSI-2 to parallel) but especially CSI-2 receiver drivers that have DMA: the poor driver developer would not only need to know camera sensor specific formats but to choose the specific packing of that format suitable for the DMA used by the hardware. It is unlikely many of these would ever get tested while being present on the driver API. Also adding new sensors with new embedded data formats would involve updating all bridge and CSI-2 receiver drivers. I don't expect this to be a workable approach. Instead what I'm proposing is to use specific metadata formats on the sensor devices only, on internal pads (more about those soon) of the sensors, only visible in the UAPI, and then generic mbus formats along the pipeline and finally generic V4L2 metadata formats on the DMAs (specific to bit depth and packing). This would unsnarl the two, defining what data there is (specific mbus code) and how that is transported and packed (generic mbus codes and V4L2 formats). The user space would be required to "know" the path of that data from the sensor's internal pad to the V4L2 video node. I do not see this as these devices require at least some knowledge of the pipeline, i.e. hardware at hand. Separating what the data means and how it is packed may even be beneficial: it allows separating code that interprets the data (sensor internal mbus code) from the code that accesses it (packing). These formats are in practice line based, meaning that there may be padding at the end of the line, depending on the bus as well as the DMA. If non-line based formats are needed, it is always possible to set the "height" field to 1. The internal sink pads are an alternative to source routes [1]. The source routes were not universally liked and I do have to say I like re-using existing interface concepts (pads and everything you can do with pads, including access format, selections etc.) wherever it makes sense, instead of duplicating functionality. Effectively internal sink pads behave mostly just like sink pads, but they describe a flow of data that originates from a sub-device instead of arriving to a sub-device. The SUBDEV_S_ROUTING IOCTLs are used to enable and disable routes from internal sink pads to sub-device's source pads. The subdev format IOCTLs are usable, too, so one can find which subdev format is available on given internal sink pad.
I wanted to ask what is the current status and intentions regarding this patch-set?
I am particularly interested in the internal sink pads, as I hope that is what I need for a sensor driver that I am currently working on. It is for an HDR sensor which is sending the long exposure on one virtual channel, and the short exposure on another virtual channel. While adding streams & routes to the sensor driver, which only has one source pad, the routes are invalid on the sink side (still, I can capture on 2 streams, with the routes active by default).
One way to solve that would be to add an internal sink pad. Another would have been to have a route flag, V4L2_SUBDEV_ROUTE_FL_SOURCE was proposed here, but it seems it was not approved:
https://patchwork.linuxtv.org/project/linux-media/patch/20210524104408.599645-21-tomi.valkeinen@xxxxxxxxxxxxxxxx/#129080
Thanks, Mirela
I've also pushed these here and I'll keep updating the branch, I've also included untested OV2740 patches: <URL:https://git.linuxtv.org/sailus/media_tree.git/log/?h=metadata> Questions and comments are most welcome. Preliminary media-ctl and yavta patches can be found here: <URL:https://git.retiisi.eu/?p=~sailus/yavta.git;a=shortlog;h=refs/heads/metadata> <URL:https://git.retiisi.eu/?p=~sailus/v4l-utils.git;a=shortlog;h=refs/heads/metadata> I have used IMX219 as an example on routing in a sensor driver in this version. The patches are on my master branch <URL:https://git.linuxtv.org/sailus/media_tree.git/log/>. [1] <URL:https://lore.kernel.org/linux-media/20220831141357.1396081-20-tomi.valkeinen@xxxxxxxxxxxxxxxx/> since v8: - Move the patch adding internal pad flag past the routing API reworks, as well as a few other patches, in order to separate the patches to those that could still be merged for v6.10 (routing changes) and those that couldn't (sensor API related). The patch on the edge is "media: uapi: v4l: subdev: Enable streams API". - Include Laurent's two patches to address crop API issues wrt. streams. - Add two patches to prepare for CCS driver rework (media: ccs: Move ccs_pm_get_init function up and media: ccs: Rename out label of ccs_start_streaming). - Address issues in the ov2740 driver patches (as well as the driver itself), 4 more patches towards the end of the set. - Improved generic metadata format names, align with other existing formats. - Improved ov2740 embedded data documentation. - Reworked streams and camera sensor documentation based on Laurent's comments mainly. In particular, the contradictory concept of internal source pads no longer should exist in the patches. - Fixed pad numbering in the CCS example. - Fixed S_ROUTING behaviour when len_routes is too small and when S_ROUTING isn't implemented by the driver. - Reorder sections in meta-formats.rst alphabetically. - Add a note per struct fields that certain struct v4l2_subdev_format are zero for metadata mbus codes. - CCS driver patch cleanups. - CCS driver metadata width fix for space-efficient embedded data at 16 bpp and over. - Postpone CCS frame descriptor quirk for now. - Use MIPI_CSI2_DT_USER_DEFINED(0) instead of a numerical value for compressed data datatype. since v7: - Add embedded data support for the ov2740 driver. - Add three patches on top, to add an IMMUTABLE flag to source streams when they cannot be disabled. - Improved documentation of len_routes and num_routes arguments of [GS]_ROUTING. - Remove one inclusion of twice-included media/v4l2-fwnode.h in drivers/media/i2c/ccs/ccs-core.c . - Add missing forward declaration of ccs_internal_ops in drivers/media/i2c/ccs/ccs-core.c . since v6: - Improve embedded data UAPI documentation on camera sensors. - Improve wording of stream glossary entry. - Improve internal pad flag documentation. - Fix definition of "data unit" and remove an extra "only" in INTERNAL pad flag description (1st patch). - Use IMX219 driver in examples consistently. - Remove the CSI-2 to parallel bridge from the example to simplify the example. - Minor rewording of some parts of the routing examples. - Rebase on unified sub-device state information access functions: <URL:https://lore.kernel.org/linux-media/20231027095913.1010187-1-sakari.ailus@xxxxxxxxxxxxxxx/T/#t> - In CCS driver, do not maintain current active configuration in driver's device context struct (apart from mbus codes). Rely on sub-device state locking and clean up the code. (Multiple patches towards the end of the set.) - Arrange the CCS patches early in the set towards the end of the set. - Move the patch enabling streams API to the end of the set. - Rework IOCTL argument copying condition for [GS]_ROUTING). - Handle copying back routes in S_ROUTING, do not rely on G_ROUTING IOCTL implementation. - Rebase on metadata preparation patchset v6: <URL:https://lore.kernel.org/linux-media/20231106121805.1266696-1-sakari.ailus@xxxxxxxxxxxxxxx/T/#t>. since v5: - Rebase on new set of preparation patches. - Switch CCS driver from s_stream to enable_streams/disable_streams. Keep streaming state information --- the sensor remains in streaming state if any of the streams is enabled. - Fix setting mbus code on embedded data in get_frame_desc() op in the CCS driver. since v4: - Add a patch to acquire two sub-device states that may use the same lock. - Add a patch for CCS driver to remove ccs_get_crop_compose() helper. - Add a patch for CCS driver moving acquiring and releasing the mutex to the s_stream callback. - Add a patch for CCS driver to rely on sub-device state locking using a single driver-provided lock. - Fixed calculating minimum number of routes in copying the routes (thanks, Laurent). - Moved a label in S_ROUTING handling to make Clang happy (hopefully). - Fixed setting emb_data_ctrl register for CCS embedded data support. - Rebase on Laurent's cleanup patches. - Wrap a few long lines. - Write in embedded data documentation sensor drivers generally don't allow configuring it. since v3: - Separate preparation patches from this set. - Add a definition for "Data unit", a pixel that is not image data and use it instead in format documentation. - Fix more numbered lists in dev-subdev.rst. - Remove a redundant definition for V4L2_META_FMT_GENERIC_CSI2_2_24 --- V4L2_META_FMT_GENERIC_CSI2_12 can be used instead. - Use "X" instead of "p" to denote padding in format documentation. - Use IMX219 in examples instead of CCS. - Document that the generic V4L2 CSI-2 metadata formats use padding defined in CSI-2 spec and packing defined in CCS spec. - Add patches to align [GS]_ROUTING behaviour with V4L2. This means mainly returning configured routes as part of S_ROUTING as well. "len_routes" field is added to denote the length of the array and having more routes than fits in the array is no longer an error. Also added more reserved fields. - Added trivial support for S_ROUTING (via G_ROUTING implementation) for use in drivers with static-only routes. - Added helper functions to obtain mbus format as well as crop and compose rectangles that are streams-independent. - Added a patch to define generic CSI-2 long packet types. - Removed MEDIA_BUS_FMT_IS_META() macro. It didn't seem useful in the end. - Use a single CCS embedded data format. The bit depth can be selected using the meta stream on the source pad. - Fix mbus code numbers (there were holes due to removed redundant formats). - Fix generic mbus code documentation (byte was being used instead of bit). - Fix spelling of "length". - Added a patch to remove v4l2_subdev_enable_streams_api that disables streams API. This should be merged once libcamera support for streams works nicely. - Don't use strings in printing frame descriptor flags. - Warn on string truncation in printing frame descriptor. since v2: - Add a better example, with formats. - Add CCS static data media bus codes. - Added an example demonstrating the use of internal pads. --- Is the level of detail enough for the purpose? - Improved documentation. - Added a macro to tell whether a format is a metadata format. (Documentation could be added.) - A small ReST syntax fix in the same section. - Drop leftovers of a patch checking for the INTERNAL_SOURCE flag. since v1: - Make the new pad flag just "INTERNAL", requiring either SINK or SOURCE pad flag to accompany it. Removed the union in struct v4l2_subdev_route. - Add the term "stream" to MC glossary. - Improved and fixed documentation (according to comments). - Note these formats are little endian. - Remove 1X8 from the names of the mbus codes. These formats have generally 8 bits per pixel. - Fix mbus code numbering (had holes in RFC). - Add new metadata fields to debug prints. - Fix a minor documentation build issue. Laurent Pinchart (2): media: v4l2-subdev: Fix stream handling for crop API media: v4l2-subdev: Clearly document that the crop API won't be extended Sakari Ailus (44): media: Documentation: Add "stream" into glossary media: uapi: Add generic serial metadata mbus formats media: uapi: Document which mbus format fields are valid for metadata media: uapi: v4l: Add generic 8-bit metadata format definitions media: v4l: Support line-based metadata capture media: Documentation: Additional streams generally don't harm capture media: Documentation: Document embedded data guidelines for camera sensors media: Documentation: v4l: Document internal sink pads media: Documentation: Document S_ROUTING behaviour media: v4l: subdev: Add a function to lock two sub-device states, use it media: v4l: subdev: Move G_ROUTING handling below S_ROUTING media: v4l: subdev: Copy argument back to user also for S_ROUTING media: v4l: subdev: Add len_routes field to struct v4l2_subdev_routing media: v4l: subdev: Return routes set using S_ROUTING media: v4l: subdev: Add trivial set_routing support media: ccs: No need to set streaming to false in power off media: ccs: Move ccs_pm_get_init function up media: ccs: Rename out label of ccs_start_streaming media: ccs: Use {enable,disable}_streams operations media: ccs: Track streaming state media: ccs: Move ccs_validate_csi_data_format up media: ccs: Support frame descriptors media: uapi: v4l: subdev: Enable streams API media: mc: Add INTERNAL pad flag media: uapi: ccs: Add media bus code for MIPI CCS embedded data media: Documentation: Document non-CCS use of CCS embedded data format media: Documentation: ccs: Document routing media: ccs: Add support for embedded data stream media: ccs: Remove ccs_get_crop_compose helper media: ccs: Rely on sub-device state locking media: ccs: Compute binning configuration from sub-device state media: ccs: Compute scaling configuration from sub-device state media: ccs: Remove which parameter from ccs_propagate media: uapi: Add media bus code for ov2740 embedded data media: ov2740: Fix LINK_FREQ and PIXEL_RATE control value reporting media: ov2740: Remove shorthand variables media: ov2740: Switch to {enable,disable}_streams media: ov2740: Track streaming state media: ov2740: Add support for embedded data media: ov2740: Add generic sensor fwnode properties as controls media: ov2740: Add support for G_SELECTION IOCTL media: v4l: Add V4L2_SUBDEV_ROUTE_FL_IMMUTABLE sub-device routing flag media: ccs: Add IMMUTABLE route flag media: ov2740: Add IMMUTABLE route flag .../media/drivers/camera-sensor.rst | 32 + .../userspace-api/media/drivers/ccs.rst | 38 +- .../userspace-api/media/glossary.rst | 15 + .../media/mediactl/media-types.rst | 9 + .../userspace-api/media/v4l/dev-meta.rst | 21 + .../userspace-api/media/v4l/dev-subdev.rst | 179 ++- .../userspace-api/media/v4l/meta-formats.rst | 3 +- .../media/v4l/metafmt-generic.rst | 328 +++++ .../media/v4l/subdev-formats.rst | 374 +++++- .../media/v4l/vidioc-enum-fmt.rst | 7 + .../media/v4l/vidioc-subdev-g-crop.rst | 6 +- .../media/v4l/vidioc-subdev-g-routing.rst | 60 +- .../media/videodev2.h.rst.exceptions | 1 + drivers/media/i2c/ccs/ccs-core.c | 1050 +++++++++++------ drivers/media/i2c/ccs/ccs.h | 27 +- drivers/media/i2c/ov2740.c | 304 +++-- drivers/media/mc/mc-entity.c | 15 +- drivers/media/v4l2-core/v4l2-ioctl.c | 25 +- drivers/media/v4l2-core/v4l2-subdev.c | 118 +- include/media/v4l2-subdev.h | 42 + include/uapi/linux/media-bus-format.h | 13 + include/uapi/linux/media.h | 1 + include/uapi/linux/v4l2-mediabus.h | 18 +- include/uapi/linux/v4l2-subdev.h | 18 +- include/uapi/linux/videodev2.h | 18 + 25 files changed, 2183 insertions(+), 539 deletions(-) create mode 100644 Documentation/userspace-api/media/v4l/metafmt-generic.rst
