5.4-stable review patch. If anyone has any objections, please let me know.
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From: Andy Shevchenko andriy.shevchenko@linux.intel.com
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: 8eb5c87a92c0 ("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.int... Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/firmware-guide/acpi/i2c-muxes.rst | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/Documentation/firmware-guide/acpi/i2c-muxes.rst +++ b/Documentation/firmware-guide/acpi/i2c-muxes.rst @@ -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,,) } }