[PATCH 7/8] iio: accel: bmc150: Add support for DUAL250E ACPI DSM for setting the hinge angle

[Andy Shevchenko]

On Fri, May 21, 2021 at 11:22 PM Hans de Goede <hdegoede at redhat.com> wrote:
>
> Some 360 degree hinges (yoga) style 2-in-1 devices use 2 bmc150 accels
> to allow the OS to determine the angle between the display and the base
> of the device, so that the OS can determine if the 2-in-1 is in laptop
> or in tablet-mode.
>
> On Windows both accelerometers are read (polled) by a special service
> and this service calls the DSM (Device Specific Method), which in turn
> translates the angles to one of laptop/tablet/tent/stand mode and then
> notifies the EC about the new mode and the EC then enables or disables
> the builtin keyboard and touchpad based in the mode.
>
> When the 2-in-1 is powered-on or resumed folded in tablet mode the
> EC senses this independent of the DSM by using a HALL effect sensor
> which senses that the keyboard has been folded away behind the display.
>
> At power-on or resume the EC disables the keyboard based on this and
> the only way to get the keyboard to work after this is to call the
> DSM to re-enable it.
>
> Call the DSM on probe() and resume() to fix the keyboard not working
> when powered-on / resumed in tablet-mode.
>
> This patch was developed and tested on a Lenovo Yoga 300-IBR.

...

> +       if (strcmp(acpi_device_hid(adev), "DUAL250E"))

Can we use like in the other case in this series the acpi_dev_hid_uid_match() ?

Because it's actually what you are doing here and it may be better to
see the same approach for this HID done in different places in the
code to recognize what it is about.

> +               return false;

...

> +       /*
> +        * The EC must see a change for it to re-enable the kbd, so first set the
> +        * angle to 270° (tent/stand mode) and then change it to 90° (laptop mode).
> +        */
> +       if (!bmc150_acpi_set_angle_dsm(client, 0, 270))
> +               return false;

> +       /* The EC needs some time to notice the angle being changed */
> +       msleep(100);

I feel that you conducted a research and answer to the following will
be no, but...

Do we have any means of polling something (embedded controller / ASL /
etc) to actually see the ACK for the action?

> +       return bmc150_acpi_set_angle_dsm(client, 0, 90);

...

> +       schedule_delayed_work(&data->resume_work, msecs_to_jiffies(1000));

Isn't it the same as 1 * HZ ?

-- 
With Best Regards,
Andy Shevchenko