On Thu, Jul 10, 2025 at 7:03 PM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>
> 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@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
>
> Rafael, I prefer, if no objections, to push this as v6.16-rc6 material since
> the reported issue was detected on old (v5.10.y) and still LTS kernel. Would be
> nice for people to not trap to it in older kernels.
>
> Documentation/firmware-guide/acpi/i2c-muxes.rst | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/firmware-guide/acpi/i2c-muxes.rst b/Documentation/firmware-guide/acpi/i2c-muxes.rst
> index 3a8997ccd7c4..f366539acd79 100644
> --- 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,,)
> }
> }
> --
Applied as 6.17 material, thanks!
