Thomas Zimmermann 5b4d995dfd video: Add helpers for decoding screen_info
[ Upstream commit 75fa9b7e375e35739663cde0252d31e586c6314a ]

The plain values as stored in struct screen_info need to be decoded
before being used. Add helpers that decode the type of video output
and the framebuffer I/O aperture.

Old or non-x86 systems may not set the type of video directly, but
only indicate the presence by storing 0x01 in orig_video_isVGA. The
decoding logic in screen_info_video_type() takes this into account.
It then follows similar code in vgacon's vgacon_startup() to detect
the video type from the given values.

A call to screen_info_resources() returns all known resources of the
given screen_info. The resources' values have been taken from existing
code in vgacon and vga16fb. These drivers can later be converted to
use the new interfaces.

v2:
	* return ssize_t from screen_info_resources()
	* don't call __screen_info_has_lfb() unnecessarily

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240212090736.11464-2-tzimmermann@suse.de
Stable-dep-of: c2bc958b2b03 ("fbdev: vesafb: Detect VGA compatibility from screen info's VESA attributes")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-08-11 12:47:15 +02:00
2022-09-28 09:02:20 +02:00
2024-08-03 08:54:42 +02:00

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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