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Filename Latest commit message Latest commit date
Stefan Brüns cfb926e148 drm/i915: Try EDID bitbanging on HDMI after failed read
The ACK/NACK implementation as found in e.g. the G965 has the falling
clock edge and the release of the data line after the ACK for the received
byte happen at the same time.

This is conformant with the I2C specification, which allows a zero hold
time, see footnote [3]: "A device must internally provide a hold time of
at least 300 ns for the SDA signal (with respect to the V IH(min) of the
SCL signal) to bridge the undefined region of the falling edge of SCL."

Some HDMI-to-VGA converters apparently fail to adhere to this requirement
and latch SDA at the falling clock edge, so instead of an ACK
sometimes a NACK is read and the slave (i.e. the EDID ROM) ends the
transfer.

The bitbanging releases the data line for the ACK only 1/4 bit time after
the falling clock edge, so a slave will see the correct value no matter
if it samples at the rising or the falling clock edge or in the center.

Fallback to bitbanging is already done for the CRT connector.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92685
Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/a39f080b-81a5-4c93-b3f7-7cb0a58daca3@rwthex-w2-a.rwth-ad.de
2018-01-09 10:05:35 +01:00
arch x86/gpu: add CFL to early quirks 2017-12-15 13:18:00 -08:00
block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-12-01 08:05:45 -05:00
certs
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-28 16:22:10 -08:00
Documentation docs: fix, intel_guc_loader.c has been moved to intel_guc_fw.c 2017-12-12 16:24:05 +01:00
drivers drm/i915: Try EDID bitbanging on HDMI after failed read 2018-01-09 10:05:35 +01:00
firmware
fs NFS client fixes for Linux 4.15-rc2 2017-12-01 20:04:20 -05:00
include drm/i915/cfl: Adding more Coffee Lake PCI IDs. 2017-12-20 11:24:25 -08:00
init
ipc Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
kernel Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-12-01 08:05:45 -05:00
lib RISC-V Cleanups and ABI Fixes for 4.15-rc2 2017-12-01 19:39:12 -05:00
mm Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-12-01 08:05:45 -05:00
net NFS client fixes for Linux 4.15-rc2 2017-12-01 20:04:20 -05:00
samples
scripts Merge branch 'akpm' (patches from Andrew) 2017-11-29 19:12:44 -08:00
security bug fixes: 2017-11-30 18:56:41 -05:00
sound Revert "ALSA: usb-audio: Fix potential zero-division at parsing FU" 2017-11-28 09:34:36 -08:00
tools Power management fixes for v4.15-rc2 2017-11-30 18:45:55 -05:00
usr
virt * x86 bugfixes: APIC, nested virtualization, IOAPIC 2017-11-30 08:15:19 -08:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge arlied/drm-next into drm-misc-next 2017-12-04 16:04:45 -02:00
Makefile Linux 4.15-rc2 2017-12-03 11:01:47 -05:00
README

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.