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Daniel Vetter 9e1ed9fb1e drm: Add docs for managed resources
All collected together to provide a consistent story in one patch,
instead of the somewhat bumpy refactor-evolution leading to this.

Also some thoughts on what the next steps could be:

- Create a macro called devm_drm_dev_alloc() which essentially wraps
  the kzalloc(); devm_drm_dev_init(); drmm_add_final_kfree() combo.
  Needs to be a macro since we'll have to do some typeof trickery and
  casting to make this fully generic for all drivers that embed struct
  drm_device into their own thing.

- A lot of the simple drivers now have essentially just
  drm_dev_unplug(); drm_atomic_helper_shutdown(); as their
  $bus_driver->remove hook. We could create a devm_mode_config_reset
  which sets drm_atomic_helper_shutdown as it's cleanup action, and a
  devm_drm_dev_register with drm_dev_unplug as it's cleanup action,
  and simple drivers wouldn't have a need for a ->remove function at
  all, and we could delete them.

- For more complicated drivers we need drmm_ versions of a _lot_ more
  things. All the userspace visible objects (crtc, plane, encoder,
  crtc), anything else hanging of those (maybe a drmm_get_edid, at
  least for panels and other built-in stuff).

Also some more thoughts on why we're not reusing devm_ with maybe a
fake struct device embedded into the drm_device (we can't use the
kdev, since that's in each drm_minor).

- Code review gets extremely tricky, since every time you see a devm_
  you need to carefully check whether the fake device (with the
  drm_device lifetim) or the real device (with the lifetim of the
  underlying physical device and driver binding) are used. That's not
  going to help at all, and we have enormous amounts of drivers who
  use devm_ where they really shouldn't. Having different types makes
  sure the compiler type checks this for us and ensures correctness.

- The set of functions are very much non-overlapping. E.g.
  devm_ioremap makes total sense, drmm_ioremap has the wrong lifetime,
  since hw resources need to be cleaned out at driver unbind and wont
  outlive that like a drm_device. Similar, but other way round for
  drmm_connector_init (which is the only correct version, devm_ for
  drm_connector is just buggy). Simply not having the wrong version
  again prevents bugs.

Finally I guess this opens a huge todo for all the drivers. I'm
semi-tempted to do a tree-wide s/devm_kzalloc/drmm_kzalloc/ since most
likely that'll fix an enormous amount of bugs and most likely not
cause any issues at all (aside from maybe holding onto memory slightly
too long).

v2:
- Doc improvements from Laurent.
- Also add kerneldoc for the new drmm_add_action_or_reset.

v3:
- Remove kerneldoc for drmm_remove_action.

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

fixup docs
Link: https://patchwork.freedesktop.org/patch/msgid/20200323144950.3018436-52-daniel.vetter@ffwll.ch
2020-03-26 16:09:48 +01:00
arch Linux 5.6-rc5 2020-03-11 07:27:21 +10:00
block block, bfq: fix overwrite of bfq_group pointer in bfq_find_set_group() 2020-03-06 07:00:58 -07:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
Documentation drm: Add docs for managed resources 2020-03-26 16:09:48 +01:00
drivers drm: Add docs for managed resources 2020-03-26 16:09:48 +01:00
fs Driver core / debugfs fixes for 5.6-rc5 2020-03-08 10:39:40 -05:00
include drm: Add docs for managed resources 2020-03-26 16:09:48 +01:00
init Tracing updates: 2020-02-26 10:34:42 -08:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-21 11:22:15 -08:00
kernel block-5.6-2020-03-07 2020-03-07 14:14:38 -06:00
lib Tracing updates: 2020-02-26 10:34:42 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/sl[uo]b: export __kmalloc_track(_node)_caller 2020-03-26 14:45:51 +01:00
net vsock: fix potential deadlock in transport->release() 2020-02-27 12:03:56 -08:00
samples Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
scripts parse-maintainers: Mark as executable 2020-03-06 16:29:21 -06:00
security Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
sound ASoC: Fixes for v5.6 2020-03-07 07:24:36 +01:00
tools for-linus-2020-03-07 2020-03-07 08:01:43 -06:00
usr Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
virt KVM/arm fixes for 5.6, take #1 2020-02-28 11:50:06 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore selftest/lkdtm: Use local .gitignore 2020-03-02 08:39:39 -07:00
.mailmap A handful of small documentation fixes that wandered in. 2020-02-07 13:03:10 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Hand MIPS over to Thomas 2020-02-24 22:43:18 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge remote-tracking branch 'drm/drm-next' into drm-misc-next 2020-03-26 15:11:04 +01:00
Makefile Linux 5.6-rc5 2020-03-08 17:44:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.