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authorJason Liu <jason.hui.liu@nxp.com>2020-06-19 16:57:43 +0800
committerJason Liu <jason.hui.liu@nxp.com>2020-06-19 17:32:49 +0800
commit5691e22711a4ee70f473e909d7aae76a966d819d (patch)
tree4e88bd5c194da0ae0e34583f7cac1d8998b3a462 /Documentation
parent236e62fc5e1cf1ca2367d2c6745058ea4f94760b (diff)
parentfd8cd8ac940c8b45b75474415291a3b941c865ab (diff)
Merge tag 'v5.4.47' into imx_5.4.y
* tag 'v5.4.47': (2193 commits) Linux 5.4.47 KVM: arm64: Save the host's PtrAuth keys in non-preemptible context KVM: arm64: Synchronize sysreg state on injecting an AArch32 exception ... Conflicts: arch/arm/boot/dts/imx6qdl.dtsi arch/arm/mach-imx/Kconfig arch/arm/mach-imx/common.h arch/arm/mach-imx/suspend-imx6.S arch/arm64/boot/dts/freescale/imx8qxp-mek.dts arch/powerpc/include/asm/cacheflush.h drivers/cpufreq/imx6q-cpufreq.c drivers/dma/imx-sdma.c drivers/edac/synopsys_edac.c drivers/firmware/imx/imx-scu.c drivers/net/ethernet/freescale/fec.h drivers/net/ethernet/freescale/fec_main.c drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c drivers/net/phy/phy_device.c drivers/perf/fsl_imx8_ddr_perf.c drivers/usb/cdns3/gadget.c drivers/usb/dwc3/gadget.c include/uapi/linux/dma-buf.h Signed-off-by: Jason Liu <jason.hui.liu@nxp.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-devices-system-cpu1
-rw-r--r--Documentation/admin-guide/hw-vuln/index.rst1
-rw-r--r--Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst149
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt29
-rw-r--r--Documentation/arm64/silicon-errata.rst2
-rw-r--r--Documentation/devicetree/bindings/net/fsl-fman.txt7
-rw-r--r--Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.txt2
-rw-r--r--Documentation/filesystems/porting.rst8
-rw-r--r--Documentation/kbuild/modules.rst4
-rw-r--r--Documentation/lzo.txt8
-rw-r--r--Documentation/sound/hd-audio/index.rst1
-rw-r--r--Documentation/sound/hd-audio/models.rst2
-rw-r--r--Documentation/sound/hd-audio/realtek-pc-beep.rst129
13 files changed, 333 insertions, 10 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index fc20cde63d1e..c24afa60a30e 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -486,6 +486,7 @@ What: /sys/devices/system/cpu/vulnerabilities
/sys/devices/system/cpu/vulnerabilities/spec_store_bypass
/sys/devices/system/cpu/vulnerabilities/l1tf
/sys/devices/system/cpu/vulnerabilities/mds
+ /sys/devices/system/cpu/vulnerabilities/srbds
/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
/sys/devices/system/cpu/vulnerabilities/itlb_multihit
Date: January 2018
diff --git a/Documentation/admin-guide/hw-vuln/index.rst b/Documentation/admin-guide/hw-vuln/index.rst
index 0795e3c2643f..ca4dbdd9016d 100644
--- a/Documentation/admin-guide/hw-vuln/index.rst
+++ b/Documentation/admin-guide/hw-vuln/index.rst
@@ -14,3 +14,4 @@ are configurable at compile, boot or run time.
mds
tsx_async_abort
multihit.rst
+ special-register-buffer-data-sampling.rst
diff --git a/Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst b/Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst
new file mode 100644
index 000000000000..47b1b3afac99
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst
@@ -0,0 +1,149 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+SRBDS - Special Register Buffer Data Sampling
+=============================================
+
+SRBDS is a hardware vulnerability that allows MDS :doc:`mds` techniques to
+infer values returned from special register accesses. Special register
+accesses are accesses to off core registers. According to Intel's evaluation,
+the special register reads that have a security expectation of privacy are
+RDRAND, RDSEED and SGX EGETKEY.
+
+When RDRAND, RDSEED and EGETKEY instructions are used, the data is moved
+to the core through the special register mechanism that is susceptible
+to MDS attacks.
+
+Affected processors
+--------------------
+Core models (desktop, mobile, Xeon-E3) that implement RDRAND and/or RDSEED may
+be affected.
+
+A processor is affected by SRBDS if its Family_Model and stepping is
+in the following list, with the exception of the listed processors
+exporting MDS_NO while Intel TSX is available yet not enabled. The
+latter class of processors are only affected when Intel TSX is enabled
+by software using TSX_CTRL_MSR otherwise they are not affected.
+
+ ============= ============ ========
+ common name Family_Model Stepping
+ ============= ============ ========
+ IvyBridge 06_3AH All
+
+ Haswell 06_3CH All
+ Haswell_L 06_45H All
+ Haswell_G 06_46H All
+
+ Broadwell_G 06_47H All
+ Broadwell 06_3DH All
+
+ Skylake_L 06_4EH All
+ Skylake 06_5EH All
+
+ Kabylake_L 06_8EH <= 0xC
+ Kabylake 06_9EH <= 0xD
+ ============= ============ ========
+
+Related CVEs
+------------
+
+The following CVE entry is related to this SRBDS issue:
+
+ ============== ===== =====================================
+ CVE-2020-0543 SRBDS Special Register Buffer Data Sampling
+ ============== ===== =====================================
+
+Attack scenarios
+----------------
+An unprivileged user can extract values returned from RDRAND and RDSEED
+executed on another core or sibling thread using MDS techniques.
+
+
+Mitigation mechanism
+-------------------
+Intel will release microcode updates that modify the RDRAND, RDSEED, and
+EGETKEY instructions to overwrite secret special register data in the shared
+staging buffer before the secret data can be accessed by another logical
+processor.
+
+During execution of the RDRAND, RDSEED, or EGETKEY instructions, off-core
+accesses from other logical processors will be delayed until the special
+register read is complete and the secret data in the shared staging buffer is
+overwritten.
+
+This has three effects on performance:
+
+#. RDRAND, RDSEED, or EGETKEY instructions have higher latency.
+
+#. Executing RDRAND at the same time on multiple logical processors will be
+ serialized, resulting in an overall reduction in the maximum RDRAND
+ bandwidth.
+
+#. Executing RDRAND, RDSEED or EGETKEY will delay memory accesses from other
+ logical processors that miss their core caches, with an impact similar to
+ legacy locked cache-line-split accesses.
+
+The microcode updates provide an opt-out mechanism (RNGDS_MITG_DIS) to disable
+the mitigation for RDRAND and RDSEED instructions executed outside of Intel
+Software Guard Extensions (Intel SGX) enclaves. On logical processors that
+disable the mitigation using this opt-out mechanism, RDRAND and RDSEED do not
+take longer to execute and do not impact performance of sibling logical
+processors memory accesses. The opt-out mechanism does not affect Intel SGX
+enclaves (including execution of RDRAND or RDSEED inside an enclave, as well
+as EGETKEY execution).
+
+IA32_MCU_OPT_CTRL MSR Definition
+--------------------------------
+Along with the mitigation for this issue, Intel added a new thread-scope
+IA32_MCU_OPT_CTRL MSR, (address 0x123). The presence of this MSR and
+RNGDS_MITG_DIS (bit 0) is enumerated by CPUID.(EAX=07H,ECX=0).EDX[SRBDS_CTRL =
+9]==1. This MSR is introduced through the microcode update.
+
+Setting IA32_MCU_OPT_CTRL[0] (RNGDS_MITG_DIS) to 1 for a logical processor
+disables the mitigation for RDRAND and RDSEED executed outside of an Intel SGX
+enclave on that logical processor. Opting out of the mitigation for a
+particular logical processor does not affect the RDRAND and RDSEED mitigations
+for other logical processors.
+
+Note that inside of an Intel SGX enclave, the mitigation is applied regardless
+of the value of RNGDS_MITG_DS.
+
+Mitigation control on the kernel command line
+---------------------------------------------
+The kernel command line allows control over the SRBDS mitigation at boot time
+with the option "srbds=". The option for this is:
+
+ ============= =============================================================
+ off This option disables SRBDS mitigation for RDRAND and RDSEED on
+ affected platforms.
+ ============= =============================================================
+
+SRBDS System Information
+-----------------------
+The Linux kernel provides vulnerability status information through sysfs. For
+SRBDS this can be accessed by the following sysfs file:
+/sys/devices/system/cpu/vulnerabilities/srbds
+
+The possible values contained in this file are:
+
+ ============================== =============================================
+ Not affected Processor not vulnerable
+ Vulnerable Processor vulnerable and mitigation disabled
+ Vulnerable: No microcode Processor vulnerable and microcode is missing
+ mitigation
+ Mitigation: Microcode Processor is vulnerable and mitigation is in
+ effect.
+ Mitigation: TSX disabled Processor is only vulnerable when TSX is
+ enabled while this system was booted with TSX
+ disabled.
+ Unknown: Dependent on
+ hypervisor status Running on virtual guest processor that is
+ affected but with no way to know if host
+ processor is mitigated or vulnerable.
+ ============================== =============================================
+
+SRBDS Default mitigation
+------------------------
+This new microcode serializes processor access during execution of RDRAND,
+RDSEED ensures that the shared buffer is overwritten before it is released for
+reuse. Use the "srbds=off" kernel command line to disable the mitigation for
+RDRAND and RDSEED.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 5594c8bf1dcd..13984b6cc322 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -136,6 +136,10 @@
dynamic table installation which will install SSDT
tables to /sys/firmware/acpi/tables/dynamic.
+ acpi_no_watchdog [HW,ACPI,WDT]
+ Ignore the ACPI-based watchdog interface (WDAT) and let
+ a native driver control the watchdog device instead.
+
acpi_rsdp= [ACPI,EFI,KEXEC]
Pass the RSDP address to the kernel, mostly used
on machines running EFI runtime service to boot the
@@ -2737,7 +2741,7 @@
<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
mtdparts= [MTD]
- See drivers/mtd/cmdlinepart.c.
+ See drivers/mtd/parsers/cmdlinepart.c
multitce=off [PPC] This parameter disables the use of the pSeries
firmware feature for updating multiple TCE entries
@@ -4575,6 +4579,26 @@
spia_pedr=
spia_peddr=
+ srbds= [X86,INTEL]
+ Control the Special Register Buffer Data Sampling
+ (SRBDS) mitigation.
+
+ Certain CPUs are vulnerable to an MDS-like
+ exploit which can leak bits from the random
+ number generator.
+
+ By default, this issue is mitigated by
+ microcode. However, the microcode fix can cause
+ the RDRAND and RDSEED instructions to become
+ much slower. Among other effects, this will
+ result in reduced throughput from /dev/urandom.
+
+ The microcode mitigation can be disabled with
+ the following option:
+
+ off: Disable mitigation and remove
+ performance impact to RDRAND and RDSEED
+
srcutree.counter_wrap_check [KNL]
Specifies how frequently to check for
grace-period sequence counter wrap for the
@@ -5001,8 +5025,7 @@
usbcore.old_scheme_first=
[USB] Start with the old device initialization
- scheme, applies only to low and full-speed devices
- (default 0 = off).
+ scheme (default 0 = off).
usbcore.usbfs_memory_mb=
[USB] Memory limit (in MB) for buffers allocated by
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index 5a09661330fc..59daa4c21816 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -88,6 +88,8 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1349291 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Neoverse-N1 | #1542419 | ARM64_ERRATUM_1542419 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | MMU-500 | #841119,826419 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
diff --git a/Documentation/devicetree/bindings/net/fsl-fman.txt b/Documentation/devicetree/bindings/net/fsl-fman.txt
index 299c0dcd67db..1316f0aec0cf 100644
--- a/Documentation/devicetree/bindings/net/fsl-fman.txt
+++ b/Documentation/devicetree/bindings/net/fsl-fman.txt
@@ -110,6 +110,13 @@ PROPERTIES
Usage: required
Definition: See soc/fsl/qman.txt and soc/fsl/bman.txt
+- fsl,erratum-a050385
+ Usage: optional
+ Value type: boolean
+ Definition: A boolean property. Indicates the presence of the
+ erratum A050385 which indicates that DMA transactions that are
+ split can result in a FMan lock.
+
=============================================================================
FMan MURAM Node
diff --git a/Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.txt b/Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.txt
index b739f92da58e..1f90eb39870b 100644
--- a/Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.txt
@@ -118,7 +118,7 @@ Tegra194:
--------
pcie@14180000 {
- compatible = "nvidia,tegra194-pcie", "snps,dw-pcie";
+ compatible = "nvidia,tegra194-pcie";
power-domains = <&bpmp TEGRA194_POWER_DOMAIN_PCIEX8B>;
reg = <0x00 0x14180000 0x0 0x00020000 /* appl registers (128K) */
0x00 0x38000000 0x0 0x00040000 /* configuration space (256K) */
diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index f18506083ced..26c093969573 100644
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -850,3 +850,11 @@ business doing so.
d_alloc_pseudo() is internal-only; uses outside of alloc_file_pseudo() are
very suspect (and won't work in modules). Such uses are very likely to
be misspelled d_alloc_anon().
+
+---
+
+**mandatory**
+
+[should've been added in 2016] stale comment in finish_open() nonwithstanding,
+failure exits in ->atomic_open() instances should *NOT* fput() the file,
+no matter what. Everything is handled by the caller.
diff --git a/Documentation/kbuild/modules.rst b/Documentation/kbuild/modules.rst
index 774a998dcf37..199ce72bf922 100644
--- a/Documentation/kbuild/modules.rst
+++ b/Documentation/kbuild/modules.rst
@@ -470,9 +470,9 @@ build.
The syntax of the Module.symvers file is::
- <CRC> <Symbol> <Namespace> <Module> <Export Type>
+ <CRC> <Symbol> <Module> <Export Type> <Namespace>
- 0xe1cc2a05 usb_stor_suspend USB_STORAGE drivers/usb/storage/usb-storage EXPORT_SYMBOL_GPL
+ 0xe1cc2a05 usb_stor_suspend drivers/usb/storage/usb-storage EXPORT_SYMBOL_GPL USB_STORAGE
The fields are separated by tabs and values may be empty (e.g.
if no namespace is defined for an exported symbol).
diff --git a/Documentation/lzo.txt b/Documentation/lzo.txt
index ca983328976b..f65b51523014 100644
--- a/Documentation/lzo.txt
+++ b/Documentation/lzo.txt
@@ -159,11 +159,15 @@ Byte sequences
distance = 16384 + (H << 14) + D
state = S (copy S literals after this block)
End of stream is reached if distance == 16384
+ In version 1 only, to prevent ambiguity with the RLE case when
+ ((distance & 0x803f) == 0x803f) && (261 <= length <= 264), the
+ compressor must not emit block copies where distance and length
+ meet these conditions.
In version 1 only, this instruction is also used to encode a run of
- zeros if distance = 0xbfff, i.e. H = 1 and the D bits are all 1.
+ zeros if distance = 0xbfff, i.e. H = 1 and the D bits are all 1.
In this case, it is followed by a fourth byte, X.
- run length = ((X << 3) | (0 0 0 0 0 L L L)) + 4.
+ run length = ((X << 3) | (0 0 0 0 0 L L L)) + 4
0 0 1 L L L L L (32..63)
Copy of small block within 16kB distance (preferably less than 34B)
diff --git a/Documentation/sound/hd-audio/index.rst b/Documentation/sound/hd-audio/index.rst
index f8a72ffffe66..6e12de9fc34e 100644
--- a/Documentation/sound/hd-audio/index.rst
+++ b/Documentation/sound/hd-audio/index.rst
@@ -8,3 +8,4 @@ HD-Audio
models
controls
dp-mst
+ realtek-pc-beep
diff --git a/Documentation/sound/hd-audio/models.rst b/Documentation/sound/hd-audio/models.rst
index 11298f0ce44d..0ea967d34583 100644
--- a/Documentation/sound/hd-audio/models.rst
+++ b/Documentation/sound/hd-audio/models.rst
@@ -216,8 +216,6 @@ alc298-dell-aio
ALC298 fixups on Dell AIO machines
alc275-dell-xps
ALC275 fixups on Dell XPS models
-alc256-dell-xps13
- ALC256 fixups on Dell XPS13
lenovo-spk-noise
Workaround for speaker noise on Lenovo machines
lenovo-hotkey
diff --git a/Documentation/sound/hd-audio/realtek-pc-beep.rst b/Documentation/sound/hd-audio/realtek-pc-beep.rst
new file mode 100644
index 000000000000..be47c6f76a6e
--- /dev/null
+++ b/Documentation/sound/hd-audio/realtek-pc-beep.rst
@@ -0,0 +1,129 @@
+===============================
+Realtek PC Beep Hidden Register
+===============================
+
+This file documents the "PC Beep Hidden Register", which is present in certain
+Realtek HDA codecs and controls a muxer and pair of passthrough mixers that can
+route audio between pins but aren't themselves exposed as HDA widgets. As far
+as I can tell, these hidden routes are designed to allow flexible PC Beep output
+for codecs that don't have mixer widgets in their output paths. Why it's easier
+to hide a mixer behind an undocumented vendor register than to just expose it
+as a widget, I have no idea.
+
+Register Description
+====================
+
+The register is accessed via processing coefficient 0x36 on NID 20h. Bits not
+identified below have no discernible effect on my machine, a Dell XPS 13 9350::
+
+ MSB LSB
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | |h|S|L| | B |R| | Known bits
+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+ |0|0|1|1| 0x7 |0|0x0|1| 0x7 | Reset value
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+1Ah input select (B): 2 bits
+ When zero, expose the PC Beep line (from the internal beep generator, when
+ enabled with the Set Beep Generation verb on NID 01h, or else from the
+ external PCBEEP pin) on the 1Ah pin node. When nonzero, expose the headphone
+ jack (or possibly Line In on some machines) input instead. If PC Beep is
+ selected, the 1Ah boost control has no effect.
+
+Amplify 1Ah loopback, left (L): 1 bit
+ Amplify the left channel of 1Ah before mixing it into outputs as specified
+ by h and S bits. Does not affect the level of 1Ah exposed to other widgets.
+
+Amplify 1Ah loopback, right (R): 1 bit
+ Amplify the right channel of 1Ah before mixing it into outputs as specified
+ by h and S bits. Does not affect the level of 1Ah exposed to other widgets.
+
+Loopback 1Ah to 21h [active low] (h): 1 bit
+ When zero, mix 1Ah (possibly with amplification, depending on L and R bits)
+ into 21h (headphone jack on my machine). Mixed signal respects the mute
+ setting on 21h.
+
+Loopback 1Ah to 14h (S): 1 bit
+ When one, mix 1Ah (possibly with amplification, depending on L and R bits)
+ into 14h (internal speaker on my machine). Mixed signal **ignores** the mute
+ setting on 14h and is present whenever 14h is configured as an output.
+
+Path diagrams
+=============
+
+1Ah input selection (DIV is the PC Beep divider set on NID 01h)::
+
+ <Beep generator> <PCBEEP pin> <Headphone jack>
+ | | |
+ +--DIV--+--!DIV--+ {1Ah boost control}
+ | |
+ +--(b == 0)--+--(b != 0)--+
+ |
+ >1Ah (Beep/Headphone Mic/Line In)<
+
+Loopback of 1Ah to 21h/14h::
+
+ <1Ah (Beep/Headphone Mic/Line In)>
+ |
+ {amplify if L/R}
+ |
+ +-----!h-----+-----S-----+
+ | |
+ {21h mute control} |
+ | |
+ >21h (Headphone)< >14h (Internal Speaker)<
+
+Background
+==========
+
+All Realtek HDA codecs have a vendor-defined widget with node ID 20h which
+provides access to a bank of registers that control various codec functions.
+Registers are read and written via the standard HDA processing coefficient
+verbs (Set/Get Coefficient Index, Set/Get Processing Coefficient). The node is
+named "Realtek Vendor Registers" in public datasheets' verb listings and,
+apart from that, is entirely undocumented.
+
+This particular register, exposed at coefficient 0x36 and named in commits from
+Realtek, is of note: unlike most registers, which seem to control detailed
+amplifier parameters not in scope of the HDA specification, it controls audio
+routing which could just as easily have been defined using standard HDA mixer
+and selector widgets.
+
+Specifically, it selects between two sources for the input pin widget with Node
+ID (NID) 1Ah: the widget's signal can come either from an audio jack (on my
+laptop, a Dell XPS 13 9350, it's the headphone jack, but comments in Realtek
+commits indicate that it might be a Line In on some machines) or from the PC
+Beep line (which is itself multiplexed between the codec's internal beep
+generator and external PCBEEP pin, depending on if the beep generator is
+enabled via verbs on NID 01h). Additionally, it can mix (with optional
+amplification) that signal onto the 21h and/or 14h output pins.
+
+The register's reset value is 0x3717, corresponding to PC Beep on 1Ah that is
+then amplified and mixed into both the headphones and the speakers. Not only
+does this violate the HDA specification, which says that "[a vendor defined
+beep input pin] connection may be maintained *only* while the Link reset
+(**RST#**) is asserted", it means that we cannot ignore the register if we care
+about the input that 1Ah would otherwise expose or if the PCBEEP trace is
+poorly shielded and picks up chassis noise (both of which are the case on my
+machine).
+
+Unfortunately, there are lots of ways to get this register configuration wrong.
+Linux, it seems, has gone through most of them. For one, the register resets
+after S3 suspend: judging by existing code, this isn't the case for all vendor
+registers, and it's led to some fixes that improve behavior on cold boot but
+don't last after suspend. Other fixes have successfully switched the 1Ah input
+away from PC Beep but have failed to disable both loopback paths. On my
+machine, this means that the headphone input is amplified and looped back to
+the headphone output, which uses the exact same pins! As you might expect, this
+causes terrible headphone noise, the character of which is controlled by the
+1Ah boost control. (If you've seen instructions online to fix XPS 13 headphone
+noise by changing "Headphone Mic Boost" in ALSA, now you know why.)
+
+The information here has been obtained through black-box reverse engineering of
+the ALC256 codec's behavior and is not guaranteed to be correct. It likely
+also applies for the ALC255, ALC257, ALC235, and ALC236, since those codecs
+seem to be close relatives of the ALC256. (They all share one initialization
+function.) Additionally, other codecs like the ALC225 and ALC285 also have this
+register, judging by existing fixups in ``patch_realtek.c``, but specific
+data (e.g. node IDs, bit positions, pin mappings) for those codecs may differ
+from what I've described here.