linux/sound/hda
Kai Vehmanen b37a15188e ALSA: hda: avoid write to STATESTS if controller is in reset
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>
2021-10-12 18:05:28 +02:00
..
ext ALSA: hda: fix kernel-doc warnings 2021-03-02 10:21:36 +01:00
array.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
hda_bus_type.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
hdac_bus.c ALSA: hda: add link_power op to hdac_bus_ops 2021-02-08 15:56:35 +01:00
hdac_component.c ALSA: hda/i915 - fix list corruption with concurrent probes 2020-10-09 16:46:04 +02:00
hdac_controller.c ALSA: hda: avoid write to STATESTS if controller is in reset 2021-10-12 18:05:28 +02:00
hdac_device.c ALSA: hda: fix a runtime pm issue in SOF when integrated GPU is disabled 2020-09-02 19:26:39 +02:00
hdac_i915.c ALSA: hda/i915 - fix list corruption with concurrent probes 2020-10-09 16:46:04 +02:00
hdac_regmap.c ALSA: hda: fix kernel-doc warnings 2021-03-02 10:21:36 +01:00
hdac_stream.c ALSA: hda: Fix spelling mistakes 2021-03-19 11:09:26 +01:00
hdac_sysfs.c ALSA: hda: Constify static attribute_group 2021-01-31 09:50:11 +01:00
hdmi_chmap.c ALSA: hda: Use scnprintf() for printing texts for sysfs/procfs 2020-02-18 10:15:41 +01:00
intel-dsp-config.c ALSA: hda: intel-dsp-cfg: add missing ElkhartLake PCI ID 2021-07-20 09:10:55 +02:00
intel-nhlt.c ALSA: hda: ignore invalid NHLT table 2021-03-04 09:14:36 +01:00
intel-sdw-acpi.c ALSA: hda: intel-sdw-acpi: add missing include files 2021-03-02 15:33:17 +01:00
Kconfig ALSA: hda: Revert "ALSA: hda: Allow setting preallocation again for x86" 2021-03-19 16:55:11 +01:00
local.h ALSA: hda: Unexport some local helper functions 2020-05-16 08:29:49 +02:00
Makefile ALSA: hda: move Intel SoundWire ACPI scan to dedicated module 2021-03-02 15:33:00 +01:00
trace.c ALSA: hda - Re-add tracepoints to HD-audio core driver 2015-03-23 13:17:58 +01:00
trace.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00