maintainer-entry-profile.rst (7805B)
1Media Subsystem Profile 2======================= 3 4Overview 5-------- 6 7The media subsystem covers support for a variety of devices: stream 8capture, analog and digital TV streams, cameras, remote controllers, HDMI CEC 9and media pipeline control. 10 11It covers, mainly, the contents of those directories: 12 13 - drivers/media 14 - drivers/staging/media 15 - Documentation/admin-guide/media 16 - Documentation/driver-api/media 17 - Documentation/userspace-api/media 18 - Documentation/devicetree/bindings/media/\ [1]_ 19 - include/media 20 21.. [1] Device tree bindings are maintained by the 22 OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS maintainers 23 (see the MAINTAINERS file). So, changes there must be reviewed 24 by them before being merged via the media subsystem's development 25 tree. 26 27Both media userspace and Kernel APIs are documented and the documentation 28must be kept in sync with the API changes. It means that all patches that 29add new features to the subsystem must also bring changes to the 30corresponding API files. 31 32Due to the size and wide scope of the media subsystem, media's 33maintainership model is to have sub-maintainers that have a broad 34knowledge of a specific aspect of the subsystem. It is the sub-maintainers' 35task to review the patches, providing feedback to users if the patches are 36following the subsystem rules and are properly using the media kernel and 37userspace APIs. 38 39Patches for the media subsystem must be sent to the media mailing list 40at linux-media@vger.kernel.org as plain text only e-mail. Emails with 41HTML will be automatically rejected by the mail server. It could be wise 42to also copy the sub-maintainer(s). 43 44Media's workflow is heavily based on Patchwork, meaning that, once a patch 45is submitted, the e-mail will first be accepted by the mailing list 46server, and, after a while, it should appear at: 47 48 - https://patchwork.linuxtv.org/project/linux-media/list/ 49 50If it doesn't automatically appear there after a few minutes, then 51probably something went wrong on your submission. Please check if the 52email is in plain text\ [2]_ only and if your emailer is not mangling 53whitespaces before complaining or submitting them again. 54 55You can check if the mailing list server accepted your patch, by looking at: 56 57 - https://lore.kernel.org/linux-media/ 58 59.. [2] If your email contains HTML, the mailing list server will simply 60 drop it, without any further notice. 61 62 63Media maintainers 64+++++++++++++++++ 65 66At the media subsystem, we have a group of senior developers that 67are responsible for doing the code reviews at the drivers (also known as 68sub-maintainers), and another senior developer responsible for the 69subsystem as a whole. For core changes, whenever possible, multiple 70media maintainers do the review. 71 72The media maintainers that work on specific areas of the subsystem are: 73 74- Remote Controllers (infrared): 75 Sean Young <sean@mess.org> 76 77- HDMI CEC: 78 Hans Verkuil <hverkuil@xs4all.nl> 79 80- Media controller drivers: 81 Laurent Pinchart <laurent.pinchart@ideasonboard.com> 82 83- ISP, v4l2-async, v4l2-fwnode, v4l2-flash-led-class and Sensor drivers: 84 Sakari Ailus <sakari.ailus@linux.intel.com> 85 86- V4L2 drivers and core V4L2 frameworks: 87 Hans Verkuil <hverkuil@xs4all.nl> 88 89The subsystem maintainer is: 90 Mauro Carvalho Chehab <mchehab@kernel.org> 91 92Media maintainers may delegate a patch to other media maintainers as needed. 93On such case, checkpatch's ``delegate`` field indicates who's currently 94responsible for reviewing a patch. 95 96Submit Checklist Addendum 97------------------------- 98 99Patches that change the Open Firmware/Device Tree bindings must be 100reviewed by the Device Tree maintainers. So, DT maintainers should be 101Cc:ed when those are submitted via devicetree@vger.kernel.org mailing 102list. 103 104There is a set of compliance tools at https://git.linuxtv.org/v4l-utils.git/ 105that should be used in order to check if the drivers are properly 106implementing the media APIs: 107 108==================== ======================================================= 109Type Tool 110==================== ======================================================= 111V4L2 drivers\ [3]_ ``v4l2-compliance`` 112V4L2 virtual drivers ``contrib/test/test-media`` 113CEC drivers ``cec-compliance`` 114==================== ======================================================= 115 116.. [3] The ``v4l2-compliance`` also covers the media controller usage inside 117 V4L2 drivers. 118 119Other compilance tools are under development to check other parts of the 120subsystem. 121 122Those tests need to pass before the patches go upstream. 123 124Also, please notice that we build the Kernel with:: 125 126 make CF=-D__CHECK_ENDIAN__ CONFIG_DEBUG_SECTION_MISMATCH=y C=1 W=1 CHECK=check_script 127 128Where the check script is:: 129 130 #!/bin/bash 131 /devel/smatch/smatch -p=kernel $@ >&2 132 /devel/sparse/sparse $@ >&2 133 134Be sure to not introduce new warnings on your patches without a 135very good reason. 136 137Style Cleanup Patches 138+++++++++++++++++++++ 139 140Style cleanups are welcome when they come together with other changes 141at the files where the style changes will affect. 142 143We may accept pure standalone style cleanups, but they should ideally 144be one patch for the whole subsystem (if the cleanup is low volume), 145or at least be grouped per directory. So, for example, if you're doing a 146big cleanup change set at drivers under drivers/media, please send a single 147patch for all drivers under drivers/media/pci, another one for 148drivers/media/usb and so on. 149 150Coding Style Addendum 151+++++++++++++++++++++ 152 153Media development uses ``checkpatch.pl`` on strict mode to verify the code 154style, e.g.:: 155 156 $ ./scripts/checkpatch.pl --strict --max-line-length=80 157 158In principle, patches should follow the coding style rules, but exceptions 159are allowed if there are good reasons. On such case, maintainers and reviewers 160may question about the rationale for not addressing the ``checkpatch.pl``. 161 162Please notice that the goal here is to improve code readability. On 163a few cases, ``checkpatch.pl`` may actually point to something that would 164look worse. So, you should use good sense. 165 166Note that addressing one ``checkpatch.pl`` issue (of any kind) alone may lead 167to having longer lines than 80 characters per line. While this is not 168strictly prohibited, efforts should be made towards staying within 80 169characters per line. This could include using re-factoring code that leads 170to less indentation, shorter variable or function names and last but not 171least, simply wrapping the lines. 172 173In particular, we accept lines with more than 80 columns: 174 175 - on strings, as they shouldn't be broken due to line length limits; 176 - when a function or variable name need to have a big identifier name, 177 which keeps hard to honor the 80 columns limit; 178 - on arithmetic expressions, when breaking lines makes them harder to 179 read; 180 - when they avoid a line to end with an open parenthesis or an open 181 bracket. 182 183Key Cycle Dates 184--------------- 185 186New submissions can be sent at any time, but if they intend to hit the 187next merge window they should be sent before -rc5, and ideally stabilized 188in the linux-media branch by -rc6. 189 190Review Cadence 191-------------- 192 193Provided that your patch is at https://patchwork.linuxtv.org, it should 194be sooner or later handled, so you don't need to re-submit a patch. 195 196Except for bug fixes, we don't usually add new patches to the development 197tree between -rc6 and the next -rc1. 198 199Please notice that the media subsystem is a high traffic one, so it 200could take a while for us to be able to review your patches. Feel free 201to ping if you don't get a feedback in a couple of weeks or to ask 202other developers to publicly add Reviewed-by and, more importantly, 203``Tested-by:`` tags. 204 205Please note that we expect a detailed description for ``Tested-by:``, 206identifying what boards were used at the test and what it was tested.