[PATCH 1/2] HID: input: Drop Asus UX550* touchscreen ignore battery quirks

[PATCH 1/2] HID: input: Drop Asus UX550* touchscreen ignore battery quirks

[Hans de Goede]

Drop the Asus UX550* touchscreen ignore battery quirks, there is a blanket
HID_BATTERY_QUIRK_IGNORE for all USB_VENDOR_ID_ELAN USB touchscreens now,
so these are just a duplicate of those.

Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
---
 drivers/hid/hid-ids.h   | 2 --
 drivers/hid/hid-input.c | 4 ----
 2 files changed, 6 deletions(-)

diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 9c2bf584d9f6..fa728b4153fb 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -446,8 +446,6 @@
 #define USB_DEVICE_ID_TOSHIBA_CLICK_L9W	0x0401
 #define USB_DEVICE_ID_HP_X2		0x074d
 #define USB_DEVICE_ID_HP_X2_10_COVER	0x0755
-#define USB_DEVICE_ID_ASUS_UX550VE_TOUCHSCREEN	0x2544
-#define USB_DEVICE_ID_ASUS_UX550_TOUCHSCREEN	0x2706
 #define I2C_DEVICE_ID_CHROMEBOOK_TROGDOR_POMPOM	0x2F81
 
 #define USB_VENDOR_ID_ELECOM		0x056e
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 2633fcd8f910..67ca1e88ce13 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -386,10 +386,6 @@ static const struct hid_device_id hid_battery_quirks[] = {
 	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_LOGITECH,
 		USB_DEVICE_ID_LOGITECH_DINOVO_EDGE_KBD),
 	  HID_BATTERY_QUIRK_IGNORE },
-	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, USB_DEVICE_ID_ASUS_UX550_TOUCHSCREEN),
-	  HID_BATTERY_QUIRK_IGNORE },
-	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, USB_DEVICE_ID_ASUS_UX550VE_TOUCHSCREEN),
-	  HID_BATTERY_QUIRK_IGNORE },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_UGEE, USB_DEVICE_ID_UGEE_XPPEN_TABLET_DECO_L),
 	  HID_BATTERY_QUIRK_AVOID_QUERY },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_UGEE, USB_DEVICE_ID_UGEE_XPPEN_TABLET_DECO_PRO_MW),
-- 
2.52.0

[PATCH 2/2] HID: input: Add HID_BATTERY_QUIRK_DYNAMIC for Elan touchscreens

[Hans de Goede]

Elan touchscreens have a HID-battery device for the stylus which is always
there even if there is no stylus.

This is causing upower to report an empty battery for the stylus and some
desktop-environments will show a notification about this, which is quite
annoying.

Because of this the HID-battery is being ignored on all Elan I2c and USB
touchscreens, but this causes there to be no battery reporting for
the stylus at all.

This adds a new HID_BATTERY_QUIRK_DYNAMIC and uses these for the Elan
touchscreens.

This new quirks causes the present value of the battery to start at 0,
which will make userspace ignore it and only sets present to 1 after
receiving a battery input report which only happens when the stylus
gets in range.

Reported-by: ggrundik@gmail.com
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221118
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
---
 drivers/hid/hid-input.c | 14 +++++++++++---
 include/linux/hid.h     |  1 +
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 67ca1e88ce13..8fc20df99b97 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -354,6 +354,7 @@ static enum power_supply_property hidinput_battery_props[] = {
 #define HID_BATTERY_QUIRK_FEATURE	(1 << 1) /* ask for feature report */
 #define HID_BATTERY_QUIRK_IGNORE	(1 << 2) /* completely ignore the battery */
 #define HID_BATTERY_QUIRK_AVOID_QUERY	(1 << 3) /* do not query the battery */
+#define HID_BATTERY_QUIRK_DYNAMIC	(1 << 4) /* report present only after life signs */
 
 static const struct hid_device_id hid_battery_quirks[] = {
 	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE,
@@ -398,8 +399,8 @@ static const struct hid_device_id hid_battery_quirks[] = {
 	 * Elan HID touchscreens seem to all report a non present battery,
 	 * set HID_BATTERY_QUIRK_IGNORE for all Elan I2C and USB HID devices.
 	 */
-	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
-	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
+	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
 	{}
 };
 
@@ -456,11 +457,14 @@ static int hidinput_get_battery_property(struct power_supply *psy,
 	int ret = 0;
 
 	switch (prop) {
-	case POWER_SUPPLY_PROP_PRESENT:
 	case POWER_SUPPLY_PROP_ONLINE:
 		val->intval = 1;
 		break;
 
+	case POWER_SUPPLY_PROP_PRESENT:
+		val->intval = dev->battery_present;
+		break;
+
 	case POWER_SUPPLY_PROP_CAPACITY:
 		if (dev->battery_status != HID_BATTERY_REPORTED &&
 		    !dev->battery_avoid_query) {
@@ -573,6 +577,8 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
 	if (quirks & HID_BATTERY_QUIRK_AVOID_QUERY)
 		dev->battery_avoid_query = true;
 
+	dev->battery_present = (quirks & HID_BATTERY_QUIRK_DYNAMIC) ? false : true;
+
 	dev->battery = power_supply_register(&dev->dev, psy_desc, &psy_cfg);
 	if (IS_ERR(dev->battery)) {
 		error = PTR_ERR(dev->battery);
@@ -628,6 +634,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
 		return;
 
 	if (hidinput_update_battery_charge_status(dev, usage, value)) {
+		dev->battery_present = true;
 		power_supply_changed(dev->battery);
 		return;
 	}
@@ -643,6 +650,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
 	if (dev->battery_status != HID_BATTERY_REPORTED ||
 	    capacity != dev->battery_capacity ||
 	    ktime_after(ktime_get_coarse(), dev->battery_ratelimit_time)) {
+		dev->battery_present = true;
 		dev->battery_capacity = capacity;
 		dev->battery_status = HID_BATTERY_REPORTED;
 		dev->battery_ratelimit_time =
diff --git a/include/linux/hid.h b/include/linux/hid.h
index dce862cafbbd..d9b54f0e8671 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -682,6 +682,7 @@ struct hid_device {
 	__s32 battery_charge_status;
 	enum hid_battery_status battery_status;
 	bool battery_avoid_query;
+	bool battery_present;
 	ktime_t battery_ratelimit_time;
 #endif
 
-- 
2.52.0

Re: [PATCH 2/2] HID: input: Add HID_BATTERY_QUIRK_DYNAMIC for Elan touchscreens

[Dmitry Torokhov]

Hi Hans,

On Sat, Feb 28, 2026 at 03:52:58PM +0100, Hans de Goede wrote:
> Elan touchscreens have a HID-battery device for the stylus which is always
> there even if there is no stylus.
> 
> This is causing upower to report an empty battery for the stylus and some
> desktop-environments will show a notification about this, which is quite
> annoying.
> 
> Because of this the HID-battery is being ignored on all Elan I2c and USB
> touchscreens, but this causes there to be no battery reporting for
> the stylus at all.
> 
> This adds a new HID_BATTERY_QUIRK_DYNAMIC and uses these for the Elan
> touchscreens.
> 
> This new quirks causes the present value of the battery to start at 0,
> which will make userspace ignore it and only sets present to 1 after
> receiving a battery input report which only happens when the stylus
> gets in range.

My understanding was that "present" attribute is to be used for
removable batteries (i.e. when a battery can be extracted from either
from the system or from a peripheral) and we want to notify userspace of
that fact). For example, if a laptop can have an additional battery UI
can show if it is installed or not, and it should not simply ignore such
power supplies.

On the other hand the "Unknown" operating status signals that we
actually do not know the state of the battery, and fits better in our
situation.

Anyway, I think we need Sebastian's input here.

> 
> Reported-by: ggrundik@gmail.com
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221118
> Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
> ---
>  drivers/hid/hid-input.c | 14 +++++++++++---
>  include/linux/hid.h     |  1 +
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index 67ca1e88ce13..8fc20df99b97 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -354,6 +354,7 @@ static enum power_supply_property hidinput_battery_props[] = {
>  #define HID_BATTERY_QUIRK_FEATURE	(1 << 1) /* ask for feature report */
>  #define HID_BATTERY_QUIRK_IGNORE	(1 << 2) /* completely ignore the battery */
>  #define HID_BATTERY_QUIRK_AVOID_QUERY	(1 << 3) /* do not query the battery */
> +#define HID_BATTERY_QUIRK_DYNAMIC	(1 << 4) /* report present only after life signs */
>  
>  static const struct hid_device_id hid_battery_quirks[] = {
>  	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE,
> @@ -398,8 +399,8 @@ static const struct hid_device_id hid_battery_quirks[] = {
>  	 * Elan HID touchscreens seem to all report a non present battery,
>  	 * set HID_BATTERY_QUIRK_IGNORE for all Elan I2C and USB HID devices.
>  	 */
> -	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
> -	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
> +	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
> +	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
>  	{}
>  };
>  
> @@ -456,11 +457,14 @@ static int hidinput_get_battery_property(struct power_supply *psy,
>  	int ret = 0;
>  
>  	switch (prop) {
> -	case POWER_SUPPLY_PROP_PRESENT:
>  	case POWER_SUPPLY_PROP_ONLINE:
>  		val->intval = 1;
>  		break;
>  
> +	case POWER_SUPPLY_PROP_PRESENT:
> +		val->intval = dev->battery_present;
> +		break;
> +
>  	case POWER_SUPPLY_PROP_CAPACITY:
>  		if (dev->battery_status != HID_BATTERY_REPORTED &&
>  		    !dev->battery_avoid_query) {
> @@ -573,6 +577,8 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
>  	if (quirks & HID_BATTERY_QUIRK_AVOID_QUERY)
>  		dev->battery_avoid_query = true;
>  
> +	dev->battery_present = (quirks & HID_BATTERY_QUIRK_DYNAMIC) ? false : true;
> +
>  	dev->battery = power_supply_register(&dev->dev, psy_desc, &psy_cfg);
>  	if (IS_ERR(dev->battery)) {
>  		error = PTR_ERR(dev->battery);
> @@ -628,6 +634,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
>  		return;
>  
>  	if (hidinput_update_battery_charge_status(dev, usage, value)) {
> +		dev->battery_present = true;
>  		power_supply_changed(dev->battery);
>  		return;
>  	}
> @@ -643,6 +650,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
>  	if (dev->battery_status != HID_BATTERY_REPORTED ||
>  	    capacity != dev->battery_capacity ||
>  	    ktime_after(ktime_get_coarse(), dev->battery_ratelimit_time)) {
> +		dev->battery_present = true;
>  		dev->battery_capacity = capacity;
>  		dev->battery_status = HID_BATTERY_REPORTED;
>  		dev->battery_ratelimit_time =
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index dce862cafbbd..d9b54f0e8671 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -682,6 +682,7 @@ struct hid_device {
>  	__s32 battery_charge_status;
>  	enum hid_battery_status battery_status;
>  	bool battery_avoid_query;
> +	bool battery_present;
>  	ktime_t battery_ratelimit_time;
>  #endif
>  

Thanks.

-- 
Dmitry

Re: [PATCH 2/2] HID: input: Add HID_BATTERY_QUIRK_DYNAMIC for Elan touchscreens

[Hans de Goede]

Hi Dmitry,

On 2-Mar-26 1:44 AM, Dmitry Torokhov wrote:
> Hi Hans,
> 
> On Sat, Feb 28, 2026 at 03:52:58PM +0100, Hans de Goede wrote:
>> Elan touchscreens have a HID-battery device for the stylus which is always
>> there even if there is no stylus.
>>
>> This is causing upower to report an empty battery for the stylus and some
>> desktop-environments will show a notification about this, which is quite
>> annoying.
>>
>> Because of this the HID-battery is being ignored on all Elan I2c and USB
>> touchscreens, but this causes there to be no battery reporting for
>> the stylus at all.
>>
>> This adds a new HID_BATTERY_QUIRK_DYNAMIC and uses these for the Elan
>> touchscreens.
>>
>> This new quirks causes the present value of the battery to start at 0,
>> which will make userspace ignore it and only sets present to 1 after
>> receiving a battery input report which only happens when the stylus
>> gets in range.
> 
> My understanding was that "present" attribute is to be used for
> removable batteries (i.e. when a battery can be extracted from either
> from the system or from a peripheral) and we want to notify userspace of
> that fact).

In this case we have a touchscreen and a stylus with a battery embedded
in the stylus and we're setting present to 0 when the stylus (and thus
the battery) is not there. I realize this is a bit different but it
is close enough IMHO.

Also keep in mind that most people simply do not have the stylus at all,
these styluses are typically an optional accessory and some models where
the touchscreen supports this the vendor is not even selling a stylus to
go with the 2-in-1 laptop (but you may use a compatible stylus from other
vendors).

TL;DR; the user not having a stylus at all is the most common use case here.

> For example, if a laptop can have an additional battery UI
> can show if it is installed or not, and it should not simply ignore such
> power supplies.

As the screenshots of the KDE control-panel in the bug for this:
https://bugzilla.kernel.org/show_bug.cgi?id=221118

Show it is not being ignored, but its charge-level is ignored,
with the battery being shown as not present. Which is pretty much
what we want.

> On the other hand the "Unknown" operating status signals that we
> actually do not know the state of the battery, and fits better in our
> situation.

Reporting "Unknown" in the status attribute is not something which
drivers normally do. It is there in the ABI and upower seems to somewhat
handle it, but upower only handles it in that it forwards it to upower
DBUS API users it does not reset history, etc. as it does for present=0.

The problem with status=Unknown is that its meaning is not really well
defined. Unknown status mostly means that it is unknown if the battery is
charging / discharging / full for some reason. But if there still is a low
capacity reading then userspace might still warn about the low capacity in
this case, since the battery is still almost empty and presumably not
charging.

Also when the stylus is not there, the battery state is not unknown,
the entire stylus, including the battery is simply not there, so
reporting present=0 seems more appropriate and its meaning is well
defined and present=0 causes upower to not read/report any of the
other attributes.

And as mentioned most users will not have the stylus I think having
a non-present "ELAN Touchscreen Stylus battery" being reported makes
some sense to end users, where as having the same battery being
reported "Unknown" status and at 0% charge (Unknown status batteries
do have a charge) is more confusing for users.

> Anyway, I think we need Sebastian's input here.

Ack, Sebastian your input would be appreciated here ?

Regards,

Hans



> 
>>
>> Reported-by: ggrundik@gmail.com
>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221118
>> Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
>> ---
>>  drivers/hid/hid-input.c | 14 +++++++++++---
>>  include/linux/hid.h     |  1 +
>>  2 files changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
>> index 67ca1e88ce13..8fc20df99b97 100644
>> --- a/drivers/hid/hid-input.c
>> +++ b/drivers/hid/hid-input.c
>> @@ -354,6 +354,7 @@ static enum power_supply_property hidinput_battery_props[] = {
>>  #define HID_BATTERY_QUIRK_FEATURE	(1 << 1) /* ask for feature report */
>>  #define HID_BATTERY_QUIRK_IGNORE	(1 << 2) /* completely ignore the battery */
>>  #define HID_BATTERY_QUIRK_AVOID_QUERY	(1 << 3) /* do not query the battery */
>> +#define HID_BATTERY_QUIRK_DYNAMIC	(1 << 4) /* report present only after life signs */
>>  
>>  static const struct hid_device_id hid_battery_quirks[] = {
>>  	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE,
>> @@ -398,8 +399,8 @@ static const struct hid_device_id hid_battery_quirks[] = {
>>  	 * Elan HID touchscreens seem to all report a non present battery,
>>  	 * set HID_BATTERY_QUIRK_IGNORE for all Elan I2C and USB HID devices.
>>  	 */
>> -	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
>> -	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
>> +	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
>> +	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
>>  	{}
>>  };
>>  
>> @@ -456,11 +457,14 @@ static int hidinput_get_battery_property(struct power_supply *psy,
>>  	int ret = 0;
>>  
>>  	switch (prop) {
>> -	case POWER_SUPPLY_PROP_PRESENT:
>>  	case POWER_SUPPLY_PROP_ONLINE:
>>  		val->intval = 1;
>>  		break;
>>  
>> +	case POWER_SUPPLY_PROP_PRESENT:
>> +		val->intval = dev->battery_present;
>> +		break;
>> +
>>  	case POWER_SUPPLY_PROP_CAPACITY:
>>  		if (dev->battery_status != HID_BATTERY_REPORTED &&
>>  		    !dev->battery_avoid_query) {
>> @@ -573,6 +577,8 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
>>  	if (quirks & HID_BATTERY_QUIRK_AVOID_QUERY)
>>  		dev->battery_avoid_query = true;
>>  
>> +	dev->battery_present = (quirks & HID_BATTERY_QUIRK_DYNAMIC) ? false : true;
>> +
>>  	dev->battery = power_supply_register(&dev->dev, psy_desc, &psy_cfg);
>>  	if (IS_ERR(dev->battery)) {
>>  		error = PTR_ERR(dev->battery);
>> @@ -628,6 +634,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
>>  		return;
>>  
>>  	if (hidinput_update_battery_charge_status(dev, usage, value)) {
>> +		dev->battery_present = true;
>>  		power_supply_changed(dev->battery);
>>  		return;
>>  	}
>> @@ -643,6 +650,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
>>  	if (dev->battery_status != HID_BATTERY_REPORTED ||
>>  	    capacity != dev->battery_capacity ||
>>  	    ktime_after(ktime_get_coarse(), dev->battery_ratelimit_time)) {
>> +		dev->battery_present = true;
>>  		dev->battery_capacity = capacity;
>>  		dev->battery_status = HID_BATTERY_REPORTED;
>>  		dev->battery_ratelimit_time =
>> diff --git a/include/linux/hid.h b/include/linux/hid.h
>> index dce862cafbbd..d9b54f0e8671 100644
>> --- a/include/linux/hid.h
>> +++ b/include/linux/hid.h
>> @@ -682,6 +682,7 @@ struct hid_device {
>>  	__s32 battery_charge_status;
>>  	enum hid_battery_status battery_status;
>>  	bool battery_avoid_query;
>> +	bool battery_present;
>>  	ktime_t battery_ratelimit_time;
>>  #endif
>>  
> 
> Thanks.
> 

Re: [PATCH 2/2] HID: input: Add HID_BATTERY_QUIRK_DYNAMIC for Elan touchscreens

[Sebastian Reichel]

[-- Attachment #1: Type: text/plain, Size: 8197 bytes --]

Hi,

On Mon, Mar 02, 2026 at 10:19:59AM +0100, Hans de Goede wrote:
> Hi Dmitry,
> 
> On 2-Mar-26 1:44 AM, Dmitry Torokhov wrote:
> > Hi Hans,
> > 
> > On Sat, Feb 28, 2026 at 03:52:58PM +0100, Hans de Goede wrote:
> >> Elan touchscreens have a HID-battery device for the stylus which is always
> >> there even if there is no stylus.
> >>
> >> This is causing upower to report an empty battery for the stylus and some
> >> desktop-environments will show a notification about this, which is quite
> >> annoying.
> >>
> >> Because of this the HID-battery is being ignored on all Elan I2c and USB
> >> touchscreens, but this causes there to be no battery reporting for
> >> the stylus at all.
> >>
> >> This adds a new HID_BATTERY_QUIRK_DYNAMIC and uses these for the Elan
> >> touchscreens.
> >>
> >> This new quirks causes the present value of the battery to start at 0,
> >> which will make userspace ignore it and only sets present to 1 after
> >> receiving a battery input report which only happens when the stylus
> >> gets in range.
> > 
> > My understanding was that "present" attribute is to be used for
> > removable batteries (i.e. when a battery can be extracted from either
> > from the system or from a peripheral) and we want to notify userspace of
> > that fact).
> 
> In this case we have a touchscreen and a stylus with a battery embedded
> in the stylus and we're setting present to 0 when the stylus (and thus
> the battery) is not there. I realize this is a bit different but it
> is close enough IMHO.
> 
> Also keep in mind that most people simply do not have the stylus at all,
> these styluses are typically an optional accessory and some models where
> the touchscreen supports this the vendor is not even selling a stylus to
> go with the 2-in-1 laptop (but you may use a compatible stylus from other
> vendors).
> 
> TL;DR; the user not having a stylus at all is the most common use case here.
> 
> > For example, if a laptop can have an additional battery UI
> > can show if it is installed or not, and it should not simply ignore such
> > power supplies.
> 
> As the screenshots of the KDE control-panel in the bug for this:
> https://bugzilla.kernel.org/show_bug.cgi?id=221118
> 
> Show it is not being ignored, but its charge-level is ignored,
> with the battery being shown as not present. Which is pretty much
> what we want.
> 
> > On the other hand the "Unknown" operating status signals that we
> > actually do not know the state of the battery, and fits better in our
> > situation.
> 
> Reporting "Unknown" in the status attribute is not something which
> drivers normally do. It is there in the ABI and upower seems to somewhat
> handle it, but upower only handles it in that it forwards it to upower
> DBUS API users it does not reset history, etc. as it does for present=0.
> 
> The problem with status=Unknown is that its meaning is not really well
> defined. Unknown status mostly means that it is unknown if the battery is
> charging / discharging / full for some reason. But if there still is a low
> capacity reading then userspace might still warn about the low capacity in
> this case, since the battery is still almost empty and presumably not
> charging.
> 
> Also when the stylus is not there, the battery state is not unknown,
> the entire stylus, including the battery is simply not there, so
> reporting present=0 seems more appropriate and its meaning is well
> defined and present=0 causes upower to not read/report any of the
> other attributes.
> 
> And as mentioned most users will not have the stylus I think having
> a non-present "ELAN Touchscreen Stylus battery" being reported makes
> some sense to end users, where as having the same battery being
> reported "Unknown" status and at 0% charge (Unknown status batteries
> do have a charge) is more confusing for users.
> 
> > Anyway, I think we need Sebastian's input here.
> 
> Ack, Sebastian your input would be appreciated here ?

The rationale and the patch LGTM. The other option would be to not
register the battery device in the first place and do that once the
first report arrived.

Greetings,

-- Sebastian

> 
> Regards,
> 
> Hans
> 
> 
> 
> > 
> >>
> >> Reported-by: ggrundik@gmail.com
> >> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221118
> >> Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
> >> ---
> >>  drivers/hid/hid-input.c | 14 +++++++++++---
> >>  include/linux/hid.h     |  1 +
> >>  2 files changed, 12 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> >> index 67ca1e88ce13..8fc20df99b97 100644
> >> --- a/drivers/hid/hid-input.c
> >> +++ b/drivers/hid/hid-input.c
> >> @@ -354,6 +354,7 @@ static enum power_supply_property hidinput_battery_props[] = {
> >>  #define HID_BATTERY_QUIRK_FEATURE	(1 << 1) /* ask for feature report */
> >>  #define HID_BATTERY_QUIRK_IGNORE	(1 << 2) /* completely ignore the battery */
> >>  #define HID_BATTERY_QUIRK_AVOID_QUERY	(1 << 3) /* do not query the battery */
> >> +#define HID_BATTERY_QUIRK_DYNAMIC	(1 << 4) /* report present only after life signs */
> >>  
> >>  static const struct hid_device_id hid_battery_quirks[] = {
> >>  	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE,
> >> @@ -398,8 +399,8 @@ static const struct hid_device_id hid_battery_quirks[] = {
> >>  	 * Elan HID touchscreens seem to all report a non present battery,
> >>  	 * set HID_BATTERY_QUIRK_IGNORE for all Elan I2C and USB HID devices.
> >>  	 */
> >> -	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
> >> -	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
> >> +	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
> >> +	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
> >>  	{}
> >>  };
> >>  
> >> @@ -456,11 +457,14 @@ static int hidinput_get_battery_property(struct power_supply *psy,
> >>  	int ret = 0;
> >>  
> >>  	switch (prop) {
> >> -	case POWER_SUPPLY_PROP_PRESENT:
> >>  	case POWER_SUPPLY_PROP_ONLINE:
> >>  		val->intval = 1;
> >>  		break;
> >>  
> >> +	case POWER_SUPPLY_PROP_PRESENT:
> >> +		val->intval = dev->battery_present;
> >> +		break;
> >> +
> >>  	case POWER_SUPPLY_PROP_CAPACITY:
> >>  		if (dev->battery_status != HID_BATTERY_REPORTED &&
> >>  		    !dev->battery_avoid_query) {
> >> @@ -573,6 +577,8 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
> >>  	if (quirks & HID_BATTERY_QUIRK_AVOID_QUERY)
> >>  		dev->battery_avoid_query = true;
> >>  
> >> +	dev->battery_present = (quirks & HID_BATTERY_QUIRK_DYNAMIC) ? false : true;
> >> +
> >>  	dev->battery = power_supply_register(&dev->dev, psy_desc, &psy_cfg);
> >>  	if (IS_ERR(dev->battery)) {
> >>  		error = PTR_ERR(dev->battery);
> >> @@ -628,6 +634,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
> >>  		return;
> >>  
> >>  	if (hidinput_update_battery_charge_status(dev, usage, value)) {
> >> +		dev->battery_present = true;
> >>  		power_supply_changed(dev->battery);
> >>  		return;
> >>  	}
> >> @@ -643,6 +650,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
> >>  	if (dev->battery_status != HID_BATTERY_REPORTED ||
> >>  	    capacity != dev->battery_capacity ||
> >>  	    ktime_after(ktime_get_coarse(), dev->battery_ratelimit_time)) {
> >> +		dev->battery_present = true;
> >>  		dev->battery_capacity = capacity;
> >>  		dev->battery_status = HID_BATTERY_REPORTED;
> >>  		dev->battery_ratelimit_time =
> >> diff --git a/include/linux/hid.h b/include/linux/hid.h
> >> index dce862cafbbd..d9b54f0e8671 100644
> >> --- a/include/linux/hid.h
> >> +++ b/include/linux/hid.h
> >> @@ -682,6 +682,7 @@ struct hid_device {
> >>  	__s32 battery_charge_status;
> >>  	enum hid_battery_status battery_status;
> >>  	bool battery_avoid_query;
> >> +	bool battery_present;
> >>  	ktime_t battery_ratelimit_time;
> >>  #endif
> >>  
> > 
> > Thanks.
> > 
> 

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Re: [PATCH 2/2] HID: input: Add HID_BATTERY_QUIRK_DYNAMIC for Elan touchscreens

[Jiri Kosina]

On Mon, 2 Mar 2026, Sebastian Reichel wrote:

> The rationale and the patch LGTM.

Could I then please get your Acked-by: / Reviewed-by: recorded, so that it 
can be added when applying?

Thanks,

-- 
Jiri Kosina
SUSE Labs

Re: [PATCH 2/2] HID: input: Add HID_BATTERY_QUIRK_DYNAMIC for Elan touchscreens

[Sebastian Reichel]

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Hi,

On Sat, Feb 28, 2026 at 03:52:58PM +0100, Hans de Goede wrote:
> Elan touchscreens have a HID-battery device for the stylus which is always
> there even if there is no stylus.
> 
> This is causing upower to report an empty battery for the stylus and some
> desktop-environments will show a notification about this, which is quite
> annoying.
> 
> Because of this the HID-battery is being ignored on all Elan I2c and USB
> touchscreens, but this causes there to be no battery reporting for
> the stylus at all.
> 
> This adds a new HID_BATTERY_QUIRK_DYNAMIC and uses these for the Elan
> touchscreens.
> 
> This new quirks causes the present value of the battery to start at 0,
> which will make userspace ignore it and only sets present to 1 after
> receiving a battery input report which only happens when the stylus
> gets in range.
> 
> Reported-by: ggrundik@gmail.com
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221118
> Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
> ---

Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>

-- Sebastian

>  drivers/hid/hid-input.c | 14 +++++++++++---
>  include/linux/hid.h     |  1 +
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index 67ca1e88ce13..8fc20df99b97 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -354,6 +354,7 @@ static enum power_supply_property hidinput_battery_props[] = {
>  #define HID_BATTERY_QUIRK_FEATURE	(1 << 1) /* ask for feature report */
>  #define HID_BATTERY_QUIRK_IGNORE	(1 << 2) /* completely ignore the battery */
>  #define HID_BATTERY_QUIRK_AVOID_QUERY	(1 << 3) /* do not query the battery */
> +#define HID_BATTERY_QUIRK_DYNAMIC	(1 << 4) /* report present only after life signs */
>  
>  static const struct hid_device_id hid_battery_quirks[] = {
>  	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE,
> @@ -398,8 +399,8 @@ static const struct hid_device_id hid_battery_quirks[] = {
>  	 * Elan HID touchscreens seem to all report a non present battery,
>  	 * set HID_BATTERY_QUIRK_IGNORE for all Elan I2C and USB HID devices.
>  	 */
> -	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
> -	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_IGNORE },
> +	{ HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
> +	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, HID_ANY_ID), HID_BATTERY_QUIRK_DYNAMIC },
>  	{}
>  };
>  
> @@ -456,11 +457,14 @@ static int hidinput_get_battery_property(struct power_supply *psy,
>  	int ret = 0;
>  
>  	switch (prop) {
> -	case POWER_SUPPLY_PROP_PRESENT:
>  	case POWER_SUPPLY_PROP_ONLINE:
>  		val->intval = 1;
>  		break;
>  
> +	case POWER_SUPPLY_PROP_PRESENT:
> +		val->intval = dev->battery_present;
> +		break;
> +
>  	case POWER_SUPPLY_PROP_CAPACITY:
>  		if (dev->battery_status != HID_BATTERY_REPORTED &&
>  		    !dev->battery_avoid_query) {
> @@ -573,6 +577,8 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
>  	if (quirks & HID_BATTERY_QUIRK_AVOID_QUERY)
>  		dev->battery_avoid_query = true;
>  
> +	dev->battery_present = (quirks & HID_BATTERY_QUIRK_DYNAMIC) ? false : true;
> +
>  	dev->battery = power_supply_register(&dev->dev, psy_desc, &psy_cfg);
>  	if (IS_ERR(dev->battery)) {
>  		error = PTR_ERR(dev->battery);
> @@ -628,6 +634,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
>  		return;
>  
>  	if (hidinput_update_battery_charge_status(dev, usage, value)) {
> +		dev->battery_present = true;
>  		power_supply_changed(dev->battery);
>  		return;
>  	}
> @@ -643,6 +650,7 @@ static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
>  	if (dev->battery_status != HID_BATTERY_REPORTED ||
>  	    capacity != dev->battery_capacity ||
>  	    ktime_after(ktime_get_coarse(), dev->battery_ratelimit_time)) {
> +		dev->battery_present = true;
>  		dev->battery_capacity = capacity;
>  		dev->battery_status = HID_BATTERY_REPORTED;
>  		dev->battery_ratelimit_time =
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index dce862cafbbd..d9b54f0e8671 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -682,6 +682,7 @@ struct hid_device {
>  	__s32 battery_charge_status;
>  	enum hid_battery_status battery_status;
>  	bool battery_avoid_query;
> +	bool battery_present;
>  	ktime_t battery_ratelimit_time;
>  #endif
>  
> -- 
> 2.52.0

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Re: [PATCH 1/2] HID: input: Drop Asus UX550* touchscreen ignore battery quirks

[Jiri Kosina]

Both patches are now in hid.git#for-7.0/upstream-fixes

Thanks,

-- 
Jiri Kosina
SUSE Labs