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Imre Deak e42e7e5859 drm/i915: Fix modesetting in case of unexpected AUX timeouts
In case AUX failures happen unexpectedly during a modeset, the driver
should still complete the modeset. In particular the driver should
perform the link training sequence steps even in case of an AUX failure,
as this sequence also includes port initialization steps. Not doing that
can leave the port/pipe in a broken state and lead for instance to a
flip done timeout.

Fix this by continuing with link training (in a no-LTTPR mode) if the
DPRX DPCD readout failed for some reason at the beginning of link
training. After a successful connector detection we already have the
DPCD read out and cached, so the failed repeated read for it should not
cause a problem. Note that a partial AUX read could in theory partly
overwrite the cached DPCD (and return error) but this overwrite should
not happen if the returned values are corrupted (due to a timeout or
some other IO error).

Kudos to Ville to root cause the problem.

Fixes: 264613b406 ("drm/i915: Disable LTTPR support when the DPCD rev < 1.4")
References: https://gitlab.freedesktop.org/drm/intel/-/issues/3308
Cc: stable@vger.kernel.org # 5.11
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210412232413.2755054-1-imre.deak@intel.com
2021-04-14 14:09:25 +03:00
Documentation Mediatek DRM Next for Linux 5.13 2021-04-08 12:42:14 +10:00
LICENSES
arch Merge tag 'drm-intel-next-2021-03-16' of git://anongit.freedesktop.org/drm/drm-intel into drm-next 2021-03-18 08:06:34 +10:00
block block: Discard page cache of zone reset target range 2021-03-11 11:49:25 -07:00
certs
crypto crypto: mips/poly1305 - enable for all MIPS processors 2021-03-08 11:52:17 +01:00
drivers drm/i915: Fix modesetting in case of unexpected AUX timeouts 2021-04-14 14:09:25 +03:00
fs Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
include Merge tag 'drm-intel-next-2021-04-01' of git://anongit.freedesktop.org/drm/drm-intel into drm-next 2021-04-08 14:02:21 +10:00
init Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
ipc
kernel Tag for the input subsystem to pick up 2021-03-29 20:35:13 +09:00
lib drm-misc-next for 5.13: 2021-03-16 17:08:46 +10:00
mm Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
net NFS Client Bugfixes for Linux 5.10-rc3 2021-03-12 14:19:35 -08:00
samples Merge git://git.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2021-03-09 17:15:56 -08:00
scripts drm-misc-next for 5.13: 2021-03-16 17:08:46 +10:00
security Revert 95ebabde38 ("capabilities: Don't allow writing ambiguous v3 file capabilities") 2021-03-12 15:27:14 -06:00
sound ALSA: hda/hdmi: Cancel pending works before suspend 2021-03-10 12:52:01 +01:00
tools A single objtool fix to handle the PUSHF/POPF validation correctly for the 2021-03-14 13:15:55 -07:00
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MAINTAINERS Mediatek DRM Next for Linux 5.13 2021-04-08 12:42:14 +10:00
Makefile Linux 5.12-rc3 2021-03-14 14:41:02 -07:00
README

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 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.