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Documentation: ACPI: Fix parent device references

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commit e65cb011349e653ded541dddd6469c2ca813edcf upstream.

The _CRS resources in many cases want to have ResourceSource field
to be a type of ACPI String. This means that to compile properly
we need to enclosure the name path into double quotes. This will
in practice defer the interpretation to a run-time stage, However,
this may be interpreted differently on different OSes and ACPI
interpreter implementations. In particular ACPICA might not correctly
recognize the leading '^' (caret) character and will not resolve
the relative name path properly. On top of that, this piece may be
used in SSDTs which are loaded after the DSDT and on itself may also
not resolve relative name paths outside of their own scopes.
With this all said, fix documentation to use fully-qualified name
paths always to avoid any misinterpretations, which is proven to
work.

Fixes: 8eb5c87a92 ("i2c: add ACPI support for I2C mux ports")
Reported-by: Yevhen Kondrashyn <e.kondrashyn@gmail.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20250710170225.961303-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andy Shevchenko
2025-07-10 20:00:23 +03:00
committed by Greg Kroah-Hartman
parent 2a0c0c974b
commit 8c09ad855f
1 changed files with 4 additions and 4 deletions
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8
Documentation/firmware-guide/acpi/i2c-muxes.rst
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@@ -14,7 +14,7 @@ Consider this topology::
| | | 0x70 |--CH01--> i2c client B (0x50)
+------+ +------+
which corresponds to the following ASL::
which corresponds to the following ASL (in the scope of \_SB)::
Device (SMB1)
{
@@ -24,7 +24,7 @@ which corresponds to the following ASL::
Name (_HID, ...)
Name (_CRS, ResourceTemplate () {
I2cSerialBus (0x70, ControllerInitiated, I2C_SPEED,
AddressingMode7Bit, "^SMB1", 0x00,
AddressingMode7Bit, "\\_SB.SMB1", 0x00,
ResourceConsumer,,)
}
@@ -37,7 +37,7 @@ which corresponds to the following ASL::
Name (_HID, ...)
Name (_CRS, ResourceTemplate () {
I2cSerialBus (0x50, ControllerInitiated, I2C_SPEED,
AddressingMode7Bit, "^CH00", 0x00,
AddressingMode7Bit, "\\_SB.SMB1.CH00", 0x00,
ResourceConsumer,,)
}
}
@@ -52,7 +52,7 @@ which corresponds to the following ASL::
Name (_HID, ...)
Name (_CRS, ResourceTemplate () {
I2cSerialBus (0x50, ControllerInitiated, I2C_SPEED,
AddressingMode7Bit, "^CH01", 0x00,
AddressingMode7Bit, "\\_SB.SMB1.CH01", 0x00,
ResourceConsumer,,)
}
}