gpio / ACPI: Allow shared GPIO event to be read via operation region
In Microsoft Surface3 the GPIO detecting lid state is shared between GPIO event and operation region. Below is simplied version of the DSDT from Surface3 including relevant parts: Scope (GPO0) { Name (_AEI, ResourceTemplate () { GpioInt (Edge, ActiveBoth, Shared, PullNone, 0x0000, "\\_SB.GPO0", 0x00, ResourceConsumer, , ) { // Pin list 0x004C } }) OperationRegion (GPOR, GeneralPurposeIo, Zero, One) Field (GPOR, ByteAcc, NoLock, Preserve) { Connection ( GpioIo (Shared, PullNone, 0x0000, 0x0000, IoRestrictionNone, "\\_SB.GPO0", 0x00, ResourceConsumer,,) { // Pin list 0x004C } ), HELD, 1 } Method (_E4C, 0, Serialized) // _Exx: Edge-Triggered GPE { If ((HELD == One)) { ^^LID.LIDB = One } Else { ^^LID.LIDB = Zero Notify (LID, 0x80) // Status Change } Notify (^^PCI0.SPI1.NTRG, One) // Device Check } } When GPIO 0x4c changes we call ASL method _E4C which tries to read HELD field (the same GPIO). This triggers following error on the console: ACPI Error: Method parse/execution failed [\_SB.GPO0._E4C] (Node ffff88013f4b4438), AE_ERROR (20150930/psparse-542) The error happens because ACPI GPIO operation region handler (acpi_gpio_adr_space_handler()) tries to acquire the very same GPIO which returns an error (-EBUSY) because the GPIO is already reserved for the GPIO event. Fix this so that we "borrow" the event GPIO if we find the GPIO belongs to an event. Allow this only for GPIOs that are read. To be able to go through acpi_gpio->events list for operation region access we need to make sure the list is properly initialized whenever GPIO chip is registered. Link: https://bugzilla.kernel.org/show_bug.cgi?id=106571Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
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