Similar to the Surface Go (1), the (Elantech) touchscreen/digitizer in
the Surface Go 2 mistakenly reports the battery of the stylus. Instead
of over the touchscreen device, battery information is provided via
bluetooth and the touchscreen device reports an empty battery.

Apply the HID_BATTERY_QUIRK_IGNORE quirk to ignore this battery and
prevent the erroneous low battery warnings.

Cc: stable@vger.kernel.org
Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
---
 drivers/hid/hid-ids.h   | 1 +
 drivers/hid/hid-input.c | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index d9eb676abe96..9c4e92a9c646 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -413,6 +413,7 @@
 #define USB_DEVICE_ID_ASUS_UX550VE_TOUCHSCREEN	0x2544
 #define USB_DEVICE_ID_ASUS_UX550_TOUCHSCREEN	0x2706
 #define I2C_DEVICE_ID_SURFACE_GO_TOUCHSCREEN	0x261A
+#define I2C_DEVICE_ID_SURFACE_GO2_TOUCHSCREEN	0x2A1C
 
 #define USB_VENDOR_ID_ELECOM		0x056e
 #define USB_DEVICE_ID_ELECOM_BM084	0x0061
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index c6b27aab9041..48c1c02c69f4 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -381,6 +381,8 @@ static const struct hid_device_id hid_battery_quirks[] = {
 	  HID_BATTERY_QUIRK_IGNORE },
 	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, I2C_DEVICE_ID_SURFACE_GO_TOUCHSCREEN),
 	  HID_BATTERY_QUIRK_IGNORE },
+	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, I2C_DEVICE_ID_SURFACE_GO2_TOUCHSCREEN),
+	  HID_BATTERY_QUIRK_IGNORE },
 	{}
 };
 
-- 
2.36.1

On Thu, 26 May 2022, Maximilian Luz wrote:

> Similar to the Surface Go (1), the (Elantech) touchscreen/digitizer in
> the Surface Go 2 mistakenly reports the battery of the stylus. Instead
> of over the touchscreen device, battery information is provided via
> bluetooth and the touchscreen device reports an empty battery.
> 
> Apply the HID_BATTERY_QUIRK_IGNORE quirk to ignore this battery and
> prevent the erroneous low battery warnings.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
> ---
>  drivers/hid/hid-ids.h   | 1 +
>  drivers/hid/hid-input.c | 2 ++
>  2 files changed, 3 insertions(+)
> 
> diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
> index d9eb676abe96..9c4e92a9c646 100644
> --- a/drivers/hid/hid-ids.h
> +++ b/drivers/hid/hid-ids.h
> @@ -413,6 +413,7 @@
>  #define USB_DEVICE_ID_ASUS_UX550VE_TOUCHSCREEN	0x2544
>  #define USB_DEVICE_ID_ASUS_UX550_TOUCHSCREEN	0x2706
>  #define I2C_DEVICE_ID_SURFACE_GO_TOUCHSCREEN	0x261A
> +#define I2C_DEVICE_ID_SURFACE_GO2_TOUCHSCREEN	0x2A1C
>  
>  #define USB_VENDOR_ID_ELECOM		0x056e
>  #define USB_DEVICE_ID_ELECOM_BM084	0x0061
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index c6b27aab9041..48c1c02c69f4 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -381,6 +381,8 @@ static const struct hid_device_id hid_battery_quirks[] = {
>  	  HID_BATTERY_QUIRK_IGNORE },
>  	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, I2C_DEVICE_ID_SURFACE_GO_TOUCHSCREEN),
>  	  HID_BATTERY_QUIRK_IGNORE },
> +	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, I2C_DEVICE_ID_SURFACE_GO2_TOUCHSCREEN),
> +	  HID_BATTERY_QUIRK_IGNORE },

Applied, thanks.

-- 
Jiri Kosina
SUSE Labs