Re: [PATCH 5.4 regression fix] Input: soc_button_array - partial revert of support for newer surface devices

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Hi,

On 05-10-2019 14:17, Maximilian Luz wrote:
Hi,

sorry for the inconvenience this change has caused.

On 10/5/19 12:55 PM, Hans de Goede wrote:
Note ideally this seamingly unrelated change would have been made in a
separate commit, with a message explaining the what and why of this
change.

Would I have known the impact, then yes. This change was added due to
some reported instances where it seems that soc_button_array would
occasionally load on MSHW0040 before the GPIO controller was ready,
causing power and volume buttons to not work.

I guess this change may have been added to deal with -EPROBE_DEFER errors,

Correct. After a comment mentioned that gpiod_get() returning
-EPROBE_DEFER would be the proper way to detect this, I decided on this
change.

Ok, on x86 the GPIO drivers really should all be builtin because
various ACPI methods including device D0 / D3 (power-on/off) methods
may depend on them. So normally this should never happen.

If this (-EPROBE_DEFER on surface devices) somehow still is happening
please let me know and we will figure something out.

Might I suggest the following addition:

Signed-off-by: Maximilian Luz <luzmaximilian@xxxxxxxxx>

S-o-b is only for patches which pass through your hands, e.g. if
you make changes to my patch and submit a v2 of it.

I guess you mean / want one of:

Acked-by: ...

or

Reviewed-by: ...


?

Regards,

Hans



---
  drivers/input/misc/soc_button_array.c | 25 ++++++++++++++++++++-----
  1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/input/misc/soc_button_array.c b/drivers/input/misc/soc_button_array.c
index 97e3639e99d0..a0f0c977b790 100644
--- a/drivers/input/misc/soc_button_array.c
+++ b/drivers/input/misc/soc_button_array.c
@@ -92,11 +92,18 @@ soc_button_device_create(struct platform_device *pdev,
              continue;

          gpio = soc_button_lookup_gpio(&pdev->dev, info->acpi_index);
-        if (gpio < 0 && gpio != -ENOENT) {
-            error = gpio;
-            goto err_free_mem;
-        } else if (!gpio_is_valid(gpio)) {
-            /* Skip GPIO if not present */
+        if (!gpio_is_valid(gpio)) {
+            /*
+             * Skip GPIO if not present. Note we deliberately
+             * ignore -EPROBE_DEFER errors here. On some devices
+             * Intel is using so called virtual GPIOs which are not
+             * GPIOs at all but some way for AML code to check some
+             * random status bits without need a custom opregion.
+             * In some cases the resources table we parse points to
+             * such a virtual GPIO, since these are not real GPIOs
+             * we do not have a driver for these so they will never
+             * show up, therefor we ignore -EPROBE_DEFER.
+             */
              continue;
          }

@@ -429,6 +436,14 @@ static int soc_device_check_MSHW0040(struct device *dev)

      dev_dbg(dev, "OEM Platform Revision %llu\n", oem_platform_rev);

+    /*
+     * Explicitly check if GPIO controller is ready. This check is done here
+     * to avoid issues with virtual GPIOs on other chips, as elaborated above.
+     * We are at least expecting one GPIO pin for the power button (index 0).
+     */
+    if (soc_button_lookup_gpio(dev, 0) == -EPROBE_DEFER)
+        return -EPROBE_DEFER;
+
      return 0;
  }






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