On Tue, May 23, 2017 at 7:03 PM, Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> The commit 10cf4899f8af ("gpiolib: tighten up ACPI legacy gpio lookups")
> prevents to getting same resource twice if the driver asks twice using
> different connection ID.
>
> But the whole idea of fallback might bring some problems. Imagine the case when
> we have two versions of BIOS/hardware where in one _DSD is introduced along
> with GPIO resources, but the other one uses just plain GPIO resource for
> another purpose
>
> Case 1:
>
> Device (DEVX)
> {
> ...
> Name (_CRS, ResourceTemplate ()
> {
> GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
> "\\_SB.GPO0", 0, ResourceConsumer) {15}
> })
> Name (_DSD, Package ()
> {
> ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> Package ()
> {
> Package () {"some-gpios", Package() {^DEVX, 0, 0, 0 }},
> }
> })
> }
>
> Case 2:
>
> Device (DEVX)
> {
> ...
> Name (_CRS, ResourceTemplate ()
> {
> GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
> "\\_SB.GPO0", 0, ResourceConsumer) {27}
> })
> }
>
> To prevent the possible misconfiguration tighten up even more GPIO ACPI lookups
> for case without connection ID provided.
>
> In the past the issue had been triggered by "use mctrl_gpio helpers" series
> [1,2].
>
> [1] commit 4ef03d328769 ("tty/serial/8250: use mctrl_gpio helpers")
> [2] https://patchwork.kernel.org/patch/9283745/
>
> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> Cc: Bastien Nocera <hadess@xxxxxxxxxx>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Tested-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
> Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Patch applied.
Yours,
Linus Walleij
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