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Thomas Hebb 92b27256fc ALSA: hda/realtek - Set principled PC Beep configuration for ALC256 commit `c447374494` upstream. The Realtek PC Beep Hidden Register[1] is currently set by patch_realtek.c in two different places: In alc_fill_eapd_coef(), it's set to the value 0x5757, corresponding to non-beep input on 1Ah and no 1Ah loopback to either headphones or speakers. (Although, curiously, the loopback amp is still enabled.) This write was added fairly recently by commit e3743f431143 ("ALSA: hda/realtek - Dell headphone has noise on unmute for ALC236") and is a safe default. However, it happens in the wrong place: alc_fill_eapd_coef() runs on module load and cold boot but not on S3 resume, meaning the register loses its value after suspend. Conversely, in alc256_init(), the register is updated to unset bit 13 (disable speaker loopback) and set bit 5 (set non-beep input on 1Ah). Although this write does run on S3 resume, it's not quite enough to fix up the register's default value of 0x3717. What's missing is a set of bit 14 to disable headphone loopback. Without that, we end up with a feedback loop where the headphone jack is being driven by amplified samples of itself[2]. This change eliminates the update in alc256_init() and replaces it with the 0x5757 write from alc_fill_eapd_coef(). Kailang says that 0x5757 is supposed to be the codec's default value, so using it will make debugging easier for Realtek. Affects the ALC255, ALC256, ALC257, ALC235, and ALC236 codecs. [1] Newly documented in Documentation/sound/hd-audio/realtek-pc-beep.rst [2] Setting the "Headphone Mic Boost" control from userspace changes this feedback loop and has been a widely-shared workaround for headphone noise on laptops like the Dell XPS 13 9350. This commit eliminates the feedback loop and makes the workaround unnecessary. Fixes: `e1e8c1fdce` ("ALSA: hda/realtek - Dell headphone has noise on unmute for ALC236") Cc: stable@vger.kernel.org Signed-off-by: Thomas Hebb <tommyhebb@gmail.com> Link: https://lore.kernel.org/r/bf22b417d1f2474b12011c2a39ed6cf8b06d3bf5.1585584498.git.tommyhebb@gmail.com Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-04-17 10:48:45 +02:00
arch	x86/boot: Use unsigned comparison for addresses	2020-04-17 10:48:41 +02:00
block	block, bfq: fix use-after-free in bfq_idle_slice_timer_body	2020-04-17 10:48:42 +02:00
certs	export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR()	2018-08-22 23:21:44 +09:00
crypto	crypto: api - Fix race condition in crypto_spawn_alg	2020-02-11 04:34:05 -08:00
Documentation	ALSA: doc: Document PC Beep Hidden Register on Realtek ALC256	2020-04-17 10:48:44 +02:00
drivers	usb: gadget: composite: Inform controller driver of self-powered	2020-04-17 10:48:44 +02:00
firmware	Fix built-in early-load Intel microcode alignment	2020-01-23 08:21:29 +01:00
fs	btrfs: track reloc roots based on their commit root bytenr	2020-04-17 10:48:42 +02:00
include	uapi: rename ext2_swab() to swab() and share globally in swab.h	2020-04-17 10:48:43 +02:00
init	fork: fix some -Wmissing-prototypes warnings	2019-12-05 09:21:04 +01:00
ipc	Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()"	2020-02-28 16:38:49 +01:00
kernel	locking/lockdep: Avoid recursion in lockdep_count_{for,back}ward_deps()	2020-04-17 10:48:42 +02:00
lib	uapi: rename ext2_swab() to swab() and share globally in swab.h	2020-04-17 10:48:43 +02:00
LICENSES	LICENSES: Remove CC-BY-SA-4.0 license text	2018-10-18 11:28:50 +02:00
mm	slub: improve bit diffusion for freelist ptr obfuscation	2020-04-17 10:48:43 +02:00
net	Bluetooth: RFCOMM: fix ODEBUG bug in rfcomm_dev_ioctl	2020-04-13 10:45:14 +02:00
samples	samples/bpf: Don't try to remove user's homedir on clean	2020-02-11 04:34:05 -08:00
scripts	scripts/dtc: Remove redundant YYLOC global declaration	2020-04-02 15:28:17 +02:00
security	selinux: ensure we cleanup the internal AVC counters on error in avc_update()	2020-02-24 08:34:43 +01:00
sound	ALSA: hda/realtek - Set principled PC Beep configuration for ALC256	2020-04-17 10:48:45 +02:00
tools	selftests/x86/ptrace_syscall_32: Fix no-vDSO segfault	2020-04-17 10:48:40 +02:00
usr	initramfs: restore default compression behavior	2020-04-13 10:44:59 +02:00
virt	KVM: Check for a bad hva before dropping into the ghc slow path	2020-03-05 16:42:21 +01:00
.clang-format	clang-format: Set IndentWrappedFunctionNames false	2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore	Kbuild updates for v4.17 (2nd)	2018-04-15 17:21:30 -07:00
.mailmap	libnvdimm-for-4.19_misc	2018-08-25 18:13:10 -07:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	9p: remove Ron Minnich from MAINTAINERS	2018-08-17 16:20:26 -07:00
Kbuild	Kbuild updates for v4.15	2017-11-17 17:45:29 -08:00
Kconfig	kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt	2018-08-02 08:06:55 +09:00
MAINTAINERS	MAINTAINERS: Update drm/i915 bug filing URL	2020-02-28 16:38:49 +01:00
Makefile	Linux 4.19.115	2020-04-13 10:45:17 +02:00
README	Docs: Added a pointer to the formatted docs to README	2018-03-21 09:02:53 -06:00

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.
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.