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Takashi Iwai fdf35a6b22 drm: Fix broken VT switch with video=1366x768 option
I noticed that the VT switch doesn't work any longer with a Dell
laptop with 1366x768 eDP when the machine is connected with a DP
monitor.  It behaves as if VT were switched, but the graphics remain
frozen.  Actually the keyboard works, so I could switch back to VT7
again.

I tried to track down the problem, and encountered a long story until
we reach to this error:

- The machine is booted with video=1366x768 option (the distro
  installer seems to add it as default).
- Recently, drm_helper_probe_single_connector_modes() deals with
  cmdline modes, and it tries to create a new mode when no
  matching mode is found.
- The drm_mode_create_from_cmdline_mode() creates a mode based on
  either CVT of GFT according to the given cmdline mode; in our case,
  it's 1366x768.
- Since both CVT and GFT can't express the width 1366 due to
  alignment, the resultant mode becomes 1368x768, slightly larger than
  the given size.
- Later on, the atomic commit is performed, and in
  drm_atomic_check_only(), the size of each plane is checked.
- The size check of 1366x768 fails due to the above, and eventually
  the whole VT switch fails.

Back in the history, we've had a manual fix-up of 1368x768 in various
places via c09dedb7a5 ("drm/edid: Add a workaround for 1366x768 HD
panel"), but they have been all in drm_edid.c at probing the modes
from EDID.  For addressing the problem above, we need a similar hack
to the mode newly created from cmdline, manually adjusting the width
when the expected size is 1366 while we get 1368 instead.

Fixes: eaf99c749d ("drm: Perform cmdline mode parsing during...")
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20170109145614.29454-1-tiwai@suse.de
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
2017-01-11 18:46:07 +02:00
Documentation VFIO fixes for v4.10-rc3 2017-01-06 11:19:03 -08:00
arch KVM fixes for v4.10-rc3 2017-01-06 15:27:17 -08:00
block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-01-04 09:03:37 -08:00
certs certs: Add a secondary system keyring that can be added to dynamically 2016-04-11 22:48:09 +01:00
crypto crypto: testmgr - Use heap buffer for acomp test input 2016-12-27 17:32:11 +08:00
drivers drm: Fix broken VT switch with video=1366x768 option 2017-01-11 18:46:07 +02:00
firmware WHENCE: use https://linuxtv.org for LinuxTV URLs 2015-12-04 10:35:11 -02:00
fs Merge branch 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit 2017-01-05 23:06:06 -08:00
include USB fixes for 4.10-rc3 2017-01-08 11:42:04 -08:00
init mm: add PageWaiters indicating tasks are waiting for a page bit 2016-12-25 11:54:48 -08:00
ipc ipc/sem: avoid idr tree lookup for interrupted semop 2016-12-14 16:04:08 -08:00
kernel Merge branch 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit 2017-01-05 23:06:06 -08:00
lib mm: workingset: fix use-after-free in shadow node shrinker 2017-01-07 18:22:40 -08:00
mm mm: workingset: fix use-after-free in shadow node shrinker 2017-01-07 18:22:40 -08:00
net drop_monitor: consider inserted data in genlmsg_end 2017-01-03 11:09:44 -05:00
samples vfio-mdev: fix some error codes in the sample code 2017-01-04 08:32:23 -07:00
scripts gcc-plugins: update gcc-common.h for gcc-7 2017-01-03 12:08:59 -08:00
security Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sound Revert "ALSA: firewire-lib: change structure member with proper type" 2017-01-05 08:39:47 +01:00
tools Merge branch 'turbostat' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2016-12-25 14:01:28 -08:00
usr kbuild: initramfs cleanup, set target from Kconfig 2017-01-05 09:40:16 -08:00
virt Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-08-02 16:48:52 -04:00
.mailmap Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2016-10-15 09:26:12 -07:00
COPYING
CREDITS CREDITS: Remove outdated address information 2016-12-21 15:21:29 -08:00
Kbuild scripts/gdb: provide linux constants 2016-05-23 17:04:14 -07:00
Kconfig
MAINTAINERS Merge branch 'drm-fixes-4.10' of git://people.freedesktop.org/~agd5f/linux into drm-fixes 2017-01-09 09:47:19 +10:00
Makefile Linux 4.10-rc3 2017-01-08 14:18:17 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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.