[PATCH v2] pinctrl: samsung: add irq_set_affinity() for non wake up external gpio interrupt

[Sam Protsenko]

On Wed, Nov 29, 2023 at 12:32 AM Youngmin Nam <youngmin.nam at samsung.com> wrote:
> > I tried to test this patch on E850-96, and an attempt to write into
> > smp_affinity (for some GPIO irq) also fails for me:
> >
> >     # echo f0 > smp_affinity
> >     -bash: echo: write error: Input/output error
> >
> > When I add some pr_err() to exynos_irq_set_affinity(), I can't see
> > those printed in dmesg. So I guess exynos_irq_set_affinity() doesn't
> > get called at all. So the error probably happens before
> > .irq_set_affinity callback gets called.
> >
> > Youngmin, can you please try and test this patch on E850-96? This
> > board is already supported in upstream kernel. For example you can use
> > "Volume Up" interrupt for the test, which is GPIO irq.
> >
>
> I intened this affinity setting would work only on *Non* Wakeup External Interrupt.
> The "Volume Up" on E850-96 board is connected with "gpa0-7" and
> that is Wakeup External interrupt so that we can't test the callback.
>

Oh no. It was really silly mistake on my part :) But please check my
answer below for good news.

> I couldn't find out a pin for the test on E850-96 board yet.
> We can test if there is a usage of *Non" Wake up External Interrupt of GPIO
> on E850-96 board.
>
> Do you have any idea ?
>

Yep, just managed to successfully test your patch on E850-96. My
testing procedure below might appear messy, but I didn't want to do
any extra soldering :)

Used GPG1[0] pin for testing. As you can see from schematics [1],
GPG1[0] is connected to R196 resistor (which is not installed on the
board).

I've modified E850-96 dts file like this:

8<---------------------------------------------------------------------------->8
        gpio-keys {
                compatible = "gpio-keys";
                pinctrl-names = "default";
-               pinctrl-0 = <&key_voldown_pins &key_volup_pins>;
+               pinctrl-0 = <&key_voldown_pins &key_volup_pins &key_test_pins>;

                ...

+               test-key {
+                       label = "Test Key";
+                       linux,code = <KEY_RIGHTCTRL>;
+                       gpios = <&gpg1 0 GPIO_ACTIVE_LOW>;
+               };
        };

...

+&pinctrl_peri {
+       key_test_pins: key-test-pins {
+               samsung,pins = "gpg1-0";
+               samsung,pin-function = <EXYNOS_PIN_FUNC_EINT>;
+               samsung,pin-pud = <EXYNOS_PIN_PULL_NONE>;
+               samsung,pin-drv = <EXYNOS5420_PIN_DRV_LV1>;
+       };
+};
8<---------------------------------------------------------------------------->8

It appeared in /proc/interrupts as follows:

    87:          2          0          0          0          0
 0          0          0      gpg1   0 Edge      Test Key

Then I touched R196 resistor pads with my finger (emulating key press)
and looked again at /proc/interrupts:

    87:        444          0          0          0          0
 0          0          0      gpg1   0 Edge      Test Key

Then I reconfigured smp_affinity like so:

    # cat /proc/irq/87/smp_affinity
    ff
    # echo f0 > /proc/irq/87/smp_affinity
    # cat /proc/irq/87/smp_affinity
    f0

Then I messed with R196 resistor pads with my finger again, and
re-checked /proc/interrupts:

               CPU0       CPU1       CPU2       CPU3       CPU4
CPU5       CPU6       CPU7
     87:        444          0          0          0        234
  0          0          0      gpg1   0 Edge      Test Key

And without this patch that procedure above of course doesn't work.

So as far as I'm concerned, feel free to add:

Tested-by: Sam Protsenko <semen.protsenko at linaro.org>

[1] https://www.96boards.org/documentation/consumer/e850-96b/hardware-docs/files/e850-96b-schematics.pdf

Thanks!