No description
  • C 96.8%
  • Assembly 0.9%
  • Rust 0.7%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Gergo Koteles ebca08fef8 ACPI: video: Handle fetching EDID as ACPI_TYPE_PACKAGE
The _DDC method should return a buffer, or an integer in case of an error.
But some Lenovo laptops incorrectly return EDID as buffer in ACPI package.

Calling _DDC generates this ACPI Warning:
ACPI Warning: \_SB.PCI0.GP17.VGA.LCD._DDC: Return type mismatch - \
found Package, expected Integer/Buffer (20240827/nspredef-254)

Use the first element of the package to get the EDID buffer.

The DSDT:

Name (AUOP, Package (0x01)
{
	Buffer (0x80)
	{
	...
	}
})

...

Method (_DDC, 1, NotSerialized)  // _DDC: Display Data Current
{
	If ((PAID == AUID))
        {
		Return (AUOP) /* \_SB_.PCI0.GP17.VGA_.LCD_.AUOP */
	}
	ElseIf ((PAID == IVID))
	{
		Return (IVOP) /* \_SB_.PCI0.GP17.VGA_.LCD_.IVOP */
	}
	ElseIf ((PAID == BOID))
	{
		Return (BOEP) /* \_SB_.PCI0.GP17.VGA_.LCD_.BOEP */
	}
	ElseIf ((PAID == SAID))
	{
		Return (SUNG) /* \_SB_.PCI0.GP17.VGA_.LCD_.SUNG */
	}

	Return (Zero)
}

Link: https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/Apx_B_Video_Extensions/output-device-specific-methods.html#ddc-return-the-edid-for-this-device
Cc: stable@vger.kernel.org
Fixes: c6a837088b ("drm/amd/display: Fetch the EDID from _DDC if available for eDP")
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4085
Signed-off-by: Gergo Koteles <soyer@irl.hu>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/61c3df83ab73aba0bc7a941a443cd7faf4cf7fb0.1743195250.git.soyer@irl.hu
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
History 2025-03-31 17:02:14 +02:00
arch
block
certs
crypto
Documentation
drivers
fs
include Driver core api addition for 6.14-rc3 2025-02-16 12:54:42 -08:00
init
io_uring
ipc
kernel
lib
LICENSES
mm
net
rust
samples
scripts
security
sound
tools
usr
virt
.clang-format
.clippy.toml
.cocciconfig
.editorconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
.rustfmt.toml
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile
README

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 reStructuredText 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.