On May 09 2017 or thereabouts, Hans de Goede wrote:
> Hi,
>
> On 09-05-17 09:12, Benjamin Tissoires wrote:
> > Hi Hans,
> >
> > On May 07 2017 or thereabouts, Hans de Goede wrote:
> > > ACPI devices which do not have a _PSC method are assumed to have been
> > > put in D0 by the BIOS, but for touchscreens that is not always true,
> > > so call acpi_device_fix_up_power to explicitly put devices without a
> > > _PSC method into D0 state.
> > >
> > > This fixes the SIS0817 i2c-hid touchscreen on a Peaq C1010 2-in-1
> > > device failing to probe with a "hid_descr_cmd failed" error.
> > >
> > > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > > ---
> > > drivers/hid/i2c-hid/i2c-hid.c | 13 +++++++++++++
> > > 1 file changed, 13 insertions(+)
> > >
> > > diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> > > index ea3c3546cef7..c716d9605940 100644
> > > --- a/drivers/hid/i2c-hid/i2c-hid.c
> > > +++ b/drivers/hid/i2c-hid/i2c-hid.c
> > > @@ -960,6 +960,15 @@ static int i2c_hid_acpi_pdata(struct i2c_client *client,
> > > return 0;
> > > }
> > > +static void i2c_hid_acpi_fix_up_power(struct device *dev)
> > > +{
> > > + acpi_handle handle = ACPI_HANDLE(dev);
> > > + struct acpi_device *adev;
> > > +
> > > + if (handle && acpi_bus_get_device(handle, &adev) == 0)
> > > + acpi_device_fix_up_power(adev);
> >
> > I am wondering if this is not something that should be handled by
> > acpi-core or i2c-core. Looks like something pretty generic.
>
> The acpi-core deliberately does not do this, as unconditionally
> doing this for all devices is known to break things on some
> platforms, see:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7cd8407
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b9e95fc65eded
>
> So calling this is something which needs to be done an a device-by-device
> (usually actually on a driver-by-driver) basis.
>
> I don't expect this to cause any problems for i2c-hid devices
> (as the above commits shown once it was done for all ACPI enumerated devices)
> and it is necessary for some i2c-hid devices.
>
> > Also, isn't this also needed on resume (or reset_resume)?
>
> After a suspend the device is in D3, so we will always execute _PS0
> to put it back in D0. This is about devices without a _PSC method
> (which allows querying the actual state) being in D3 on boot, rather
> then the expected (and assumed) D0. Note that for devices with a _PSC
> method calling acpi_device_fix_up_power() is a nop.
>
Thanks for the extensive explanations.
Acked-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
Maybe we can add this to the commit message for future reference?
Cheers,
Benjamin
> Regards,
>
> Hans
>
> > > +}
> > > +
> > > static const struct acpi_device_id i2c_hid_acpi_match[] = {
> > > {"ACPI0C50", 0 },
> > > {"PNP0C50", 0 },
> > > @@ -972,6 +981,8 @@ static inline int i2c_hid_acpi_pdata(struct i2c_client *client,
> > > {
> > > return -ENODEV;
> > > }
> > > +
> > > +static inline void i2c_hid_acpi_fix_up_power(struct device *dev) {}
> > > #endif
> > > #ifdef CONFIG_OF
> > > @@ -1070,6 +1081,8 @@ static int i2c_hid_probe(struct i2c_client *client,
> > > if (ret < 0)
> > > goto err;
> > > + i2c_hid_acpi_fix_up_power(&client->dev);
> > > +
> > > pm_runtime_get_noresume(&client->dev);
> > > pm_runtime_set_active(&client->dev);
> > > pm_runtime_enable(&client->dev);
> > > --
> > > 2.12.2
> > >
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