Hi,

On 09-05-17 09:12, Benjamin Tissoires wrote:

Hi Hans,

On May 07 2017 or thereabouts, Hans de Goede wrote:

quoted

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 <redacted>
---
  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.

Regards,

Hans

quoted

+}
+
  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