Re: [PATCH v5] gpiolib: acpi: prevent address truncation in OperationRegion handler

[Mika Westerberg]

Hi,

On Tue, Jun 02, 2026 at 01:59:36PM +0200, Marco Scardovi wrote:
> Hi Mika,
> 
> On Tue, Jun 02, 2026 at 01:45:40PM +0200, Mika Westerberg wrote:
> > How in practice this can be done given that the GPIO resource has only 2
> > bytes for the index?
> 
> The 2-byte limitation is in the GPIO resource descriptor representation of the 
> pin table, not in the ACPI address space handler interface itself.
> 
> The acpi_gpio_adr_space_handler() receives the access offset as a 64-bit 
> acpi_physical_address from ACPICA. This value is generated when AML
> accesses a Field within the GPIO OperationRegion, and it is not constrained
> by the GPIO resource descriptor's pin_table_length.

Yes, but you access it from AML like this:

Field(\_SB.GPI2.GPO2, ByteAcc, NoLock, Preserve)
{
	Connection (GpioIo(Exclusive, PullUp, , , , "\\_SB.GPI2") {7}),
	STAT, 1,           // e.g. Status signal from the device
	Connection (GpioIo (Exclusive, PullUp, , , , "\\_SB.GPI2") {9}),
	RSET, 1            // e.g. Reset signal to the device
}

In other words it still uses GPIO resource descriptor (so 2 bytes per pin),
nothing else is accepted as far as I understand.

The example is here: 

https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#declaring-generalpurposeio-fields