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Filename Latest commit message Latest commit date
Kai Vehmanen 8de335e819 ALSA: hda: avoid write to STATESTS if controller is in reset
[ Upstream commit b37a15188eae9d4c49c5bb035e0c8d4058e4d9b3 ]

The snd_hdac_bus_reset_link() contains logic to clear STATESTS register
before performing controller reset. This code dates back to an old
bugfix in commit e8a7f136f5 ("[ALSA] hda-intel - Improve HD-audio
codec probing robustness"). Originally the code was added to
azx_reset().

The code was moved around in commit a41d122449 ("ALSA: hda - Embed bus
into controller object") and ended up to snd_hdac_bus_reset_link() and
called primarily via snd_hdac_bus_init_chip().

The logic to clear STATESTS is correct when snd_hdac_bus_init_chip() is
called when controller is not in reset. In this case, STATESTS can be
cleared. This can be useful e.g. when forcing a controller reset to retry
codec probe. A normal non-power-on reset will not clear the bits.

However, this old logic is problematic when controller is already in
reset. The HDA specification states that controller must be taken out of
reset before writing to registers other than GCTL.CRST (1.0a spec,
3.3.7). The write to STATESTS in snd_hdac_bus_reset_link() will be lost
if the controller is already in reset per the HDA specification mentioned.

This has been harmless on older hardware. On newer generation of Intel
PCIe based HDA controllers, if configured to report issues, this write
will emit an unsupported request error. If ACPI Platform Error Interface
(APEI) is enabled in kernel, this will end up to kernel log.

Fix the code in snd_hdac_bus_reset_link() to only clear the STATESTS if
the function is called when controller is not in reset. Otherwise
clearing the bits is not possible and should be skipped.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20211012142935.3731820-1-kai.vehmanen@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-10-27 09:54:29 +02:00
arch ARM: dts: spear3xx: Fix gmac node 2021-10-27 09:54:29 +02:00
block Revert "block, bfq: honor already-setup queue merges" 2021-10-06 15:42:34 +02:00
certs
crypto
Documentation
drivers platform/x86: intel_scu_ipc: Update timeout value in comment 2021-10-27 09:54:29 +02:00
fs btrfs: deal with errors when checking if a dir entry exists during log replay 2021-10-27 09:54:29 +02:00
include elfcore: correct reference to CONFIG_UML 2021-10-27 09:54:27 +02:00
init
ipc
kernel audit: fix possible null-pointer dereference in audit_filter_rules 2021-10-27 09:54:27 +02:00
lib Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH 2021-09-26 14:07:10 +02:00
LICENSES
mm mm, slub: fix potential memoryleak in kmem_cache_open() 2021-10-27 09:54:28 +02:00
net netfilter: Kconfig: use 'default y' instead of 'm' for bool config option 2021-10-27 09:54:28 +02:00
samples
scripts gcc-plugins/structleak: add makefile var for disabling structleak 2021-10-27 09:54:28 +02:00
security apparmor: remove duplicate macro list_entry_is_head() 2021-09-26 14:07:06 +02:00
sound ALSA: hda: avoid write to STATESTS if controller is in reset 2021-10-27 09:54:29 +02:00
tools selftests: netfilter: remove stray bash debug line 2021-10-27 09:54:28 +02:00
usr
virt KVM: do not shrink halt_poll_ns below grow_start 2021-10-09 14:39:50 +02:00
.clang-format
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Makefile Linux 5.4.155 2021-10-20 11:40:18 +02:00
README

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

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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    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
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the problems which may result by upgrading your kernel.