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Jani Nikula 7c648bde21 drm/i915/vbt: ignore extraneous child devices for a port
Ever since we've parsed VBT child devices, starting from 6acab15a7b
("drm/i915: use the HDMI DDI buffer translations from VBT"), we've
ignored the child device information if more than one child device
references the same port. The rationale for this seems lost in time.

Since commit 311a20949f ("drm/i915: don't init DP or HDMI when not
supported by DDI port") we started using this information more to skip
HDMI/DP init if the port wasn't there per VBT child devices. However, at
the same time it added port defaults without further explanation.

Thus, if the child device info was skipped due to multiple child devices
referencing the same port, the device info would be retrieved from the
somewhat arbitrary defaults.

Finally, when commit bb1d132935 ("drm/i915/vbt: split out defaults
that are set when there is no VBT") stopped initializing the defaults
whenever VBT is present, thus trusting the VBT more, we stopped
initializing ports which were referenced by more than one child device.

Apparently at least Asus UX305UA, UX305U, and UX306U laptops have VBT
child device blocks which cause this behaviour. Arguably they were
shipped with a broken VBT.

Relax the rules for multiple references to the same port, and use the
first child device info to reference a port. Retain the logic to debug
log about this, though.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101745
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196233
Fixes: bb1d132935 ("drm/i915/vbt: split out defaults that are set when there is no VBT")
Tested-by: Oliver Weißbarth <mail@oweissbarth.de>
Reported-by: Oliver Weißbarth <mail@oweissbarth.de>
Reported-by: Didier G <didierg-divers@orange.fr>
Reported-by: Giles Anderson <agander@gmail.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: <stable@vger.kernel.org> # v4.12+
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170811113907.6716-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit b5273d7275)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
2017-08-16 18:02:08 +03:00
Documentation fbdev fixes for v4.13-rc5: 2017-08-11 11:44:18 -07:00
arch Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2017-08-13 15:34:28 -07:00
block block: Make blk_mq_delay_kick_requeue_list() rerun the queue at a quiet time 2017-08-09 20:24:38 -06:00
certs modsign: add markers to endif-statements in certs/Makefile 2017-07-14 11:01:37 +10:00
crypto crypto: authencesn - Fix digest_null crash 2017-07-18 17:01:11 +08:00
drivers drm/i915/vbt: ignore extraneous child devices for a port 2017-08-16 18:02:08 +03:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs Some more NFS client bugfixes for 4.13 2017-08-11 13:54:09 -07:00
include tty/serial fixes for 4.13-rc5 2017-08-13 12:33:35 -07:00
init random: do not ignore early device randomness 2017-07-12 16:26:00 -07:00
ipc ipc: add missing container_of()s for randstruct 2017-08-02 17:16:12 -07:00
kernel mm: migrate: prevent racy access to tlb_flush_pending 2017-08-10 15:54:07 -07:00
lib fault-inject: fix wrong should_fail() decision in task context 2017-08-10 15:54:06 -07:00
mm rmap: do not call mmu_notifier_invalidate_page() under ptl 2017-08-10 15:54:07 -07:00
net packet: fix tp_reserve race in packet_set_ring 2017-08-10 09:52:12 -07:00
samples samples/bpf: fix bpf tunnel cleanup 2017-07-31 22:02:47 -07:00
scripts parse-maintainers: Move matching sections from MAINTAINERS 2017-08-08 11:16:14 -07:00
security Now that IPC and other changes have landed, enable manual markings for 2017-07-19 08:55:18 -07:00
sound ASoC: Fixes for v4.13 2017-08-02 17:11:45 +02:00
tools bpf: fix selftest/bpf/test_pkt_md_access on s390x 2017-08-07 10:06:27 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt KVM/ARM Fixes for v4.13-rc4 2017-08-03 17:59:58 +02:00
.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 kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS MAINTAINERS: copy virtio on balloon_compaction.c 2017-08-10 15:54:07 -07:00
Makefile Linux 4.13-rc5 2017-08-13 16:01:32 -07:00
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.