Simon Ser ec5722adb8 drm/fourcc: document modifier uniqueness requirements
There have suggestions to bake pitch alignment, address alignment,
contiguous memory or other placement (hidden VRAM, GTT/BAR, etc)
constraints into modifiers. Last time this was brought up it seemed
like the consensus was to not allow this. Document this in drm_fourcc.h.

There are several reasons for this.

- Encoding all of these constraints in the modifiers would explode the
  search space pretty quickly (we only have 64 bits to work with).
- Modifiers need to be unambiguous: a buffer can only have a single
  modifier.
- Modifier users aren't expected to parse modifiers (except drivers).

v2: add paragraph about aliases (Daniel)

v3: fix unrelated changes sent with the patch

v4: disambiguate users between driver and higher-level programs (Brian,
Daniel)

v5: fix AFBC example (Brian, Daniel)

v6: remove duplicated paragraph (Daniel)

Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Brian Starkey <brian.starkey@arm.com>
Cc: Daniel Stone <daniel@fooishbar.org>
Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Marek Olšák <maraeo@gmail.com>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Michel Dänzer <michel@daenzer.net>
Link: https://patchwork.freedesktop.org/patch/msgid/MGwgeXojKNdNXjCxuMhRlwcJM4vdYph_WJcMeGPPGMcRKtHV41XAXlh2tCc-pPJZCAhS3gwbWMWTd8f03NBA2ZYKfr0QxLhcPivpopr5c6M=@emersion.fr
2020-10-09 11:39:19 +02:00
2020-10-07 18:14:19 -03:00
2020-09-14 17:19:11 +02:00
2020-09-14 18:11:40 +02:00
2020-09-13 16:06:00 -07:00

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.
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