FAILED: patch "[PATCH] HID: input: read battery capacity from its actual report" failed to apply to 6.1-stable tree

PATCH New [email protected] 2 participants 4 messages Aug 25 – Aug 26

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Stable branch HID

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[email protected]

author maintainer

2026-08-25 13:17 UTC #0 lore raw

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x d07644524b6511b622ee7b0e2e68c9ee43d522a4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026082544-slam-derived-8e30@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d07644524b6511b622ee7b0e2e68c9ee43d522a4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jose=20Villase=C3=B1or=20Montfort?= <[email protected]>
Date: Tue, 28 Jul 2026 14:13:09 -0600
Subject: [PATCH] HID: input: read battery capacity from its actual report
offset
MIME-Version: 1.0
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hidinput_query_battery_capacity() assumes the state-of-charge value is the first byte following the report ID (buf[1]) and ignores where the battery field actually sits within the report.

An Apple Magic Trackpad 2 precedes the AbsoluteStateOfCharge byte with a byte of status flags in its battery reports, so this query returns the flags byte instead of the charge level.

The device happens to make that easy to observe, because it exposes the same cell twice: its report descriptor declares AbsoluteStateOfCharge in two reports (0x90 and 0x9b), so hidinput_setup_battery() registers two power supplies. Only the first one is refreshed by hid-magicmouse -- it uses hid_get_battery(), which returns the first battery of the list -- and that refresh goes through the report event path, which parses the field correctly. Nothing ever reports the second one, so every read of its capacity takes the query path above. On a USB-C Magic Trackpad over USB, on an unpatched 7.1.5:

  hid-<serial>-battery-144 = 100%  (Charging)      <- report event path
  hid-<serial>-battery-155 =   3%  (Discharging)   <- query path

Both are the same physical battery. A raw HIDIOCGINPUT of the two reports at that same moment:

report 0x90 -> [90 03 64]
report 0x9b -> [9b 03 64 64 00 00 10 00 00 00 00 00 00 00]

                     ^flags ^SoC = 0x64 = 100%

The device answers correctly in both cases; only the offset the kernel reads the capacity from is wrong. 0x03 is the flags byte (present, charging), reported as "3%".

Bluetooth takes the same query path for its capacity, where the trackpad reported a bogus near-constant ~4% -- 0b100, the FullyCharged flag -- regardless of the real charge.

Store the battery field's offset within the report at setup time and use it when querying, so the capacity is read from its real position. The report event path already parses the field correctly through the HID core; only the explicit GET_REPORT query was wrong.

Devices whose capacity field is the first field in the report have a report_offset of 0 and are unaffected (buf[1 + 0] == buf[1]).

Fixes 581c4484769e ("HID: input: map digitizer battery usage")

Cc [email protected]

Signed-off-by Jose Villaseñor Montfort <[email protected]>

Reviewed-by Alec Hall <[email protected]>

Signed-off-by Jiri Kosina <[email protected]>

drivers/hid/hid-input.c +13 -4

index 3487600cadb4..b55cbe7f6e20 100644
@@ -432,17 +432,25 @@ static int hidinput_scale_battery_capacity(struct hid_battery *bat,
 static int hidinput_query_battery_capacity(struct hid_battery *bat)
 {
 	int ret;
+	/*
+	 * The capacity field may not be the first field in the report: some
+	 * devices (e.g. the Apple Magic Trackpad 2 over Bluetooth) precede it
+	 * with status flags. Read it from its actual byte offset in the report
+	 * (report_offset is in bits; the leading byte is the report id).
+	 */
+	int offset = 1 + bat->report_offset / 8;
+	int len = offset + 1;
 
-	u8 *buf __free(kfree) = kmalloc(4, GFP_KERNEL);
+	u8 *buf __free(kfree) = kmalloc(max(len, 4), GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
-	ret = hid_hw_raw_request(bat->dev, bat->report_id, buf, 4,
+	ret = hid_hw_raw_request(bat->dev, bat->report_id, buf, max(len, 4),
 				 bat->report_type, HID_REQ_GET_REPORT);
-	if (ret < 2)
+	if (ret < len)
 		return -ENODATA;
 
-	return hidinput_scale_battery_capacity(bat, buf[1]);
+	return hidinput_scale_battery_capacity(bat, buf[offset]);
 }
 
 static int hidinput_get_battery_property(struct power_supply *psy,

@@ -593,6 +601,7 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
 	bat->max = max;
 	bat->report_type = report_type;
 	bat->report_id = field->report->id;
+	bat->report_offset = field->report_offset;
 	bat->charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
 	bat->status = HID_BATTERY_UNKNOWN;

include/linux/hid.h +2 -0

index 47dc0bc89fa4..51b21f98037b 100644
@@ -642,6 +642,7 @@ enum hid_battery_status {
  * @max: maximum battery value from HID descriptor
  * @report_type: HID report type (input/feature)
  * @report_id: HID report ID for this battery
+ * @report_offset: bit offset of the capacity field within its report
  * @charge_status: current charging status
  * @status: battery reporting status
  * @capacity: current battery capacity (0-100)

@@ -657,6 +658,7 @@ struct hid_battery {
 	__s32 max;
 	__s32 report_type;
 	__s32 report_id;
+	__s32 report_offset;
 	__s32 charge_status;
 	enum hid_battery_status status;
 	__s32 capacity;

Sasha Levin

maintainer

2026-08-26 18:03 UTC #1 lore raw

PATCH 1/3 HID: input: use __free(kfree) to clean up temporary buffers

From: Dmitry Torokhov <[email protected]>

[ Upstream commit 142068281f5138a9888d488e6911e8d9f7923c15 ]

The __free() cleanup automatically releases given resource when leaving the scope, so use it to make the code less cluttered with error handling.

Signed-off-by Dmitry Torokhov <[email protected]>

Signed-off-by Jiri Kosina <[email protected]>

Stable-dep-of: d07644524b65 ("HID: input: read battery capacity from its actual report offset")

Signed-off-by Sasha Levin <[email protected]>

---
 drivers/hid/hid-input.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

drivers/hid/hid-input.c +4 ~~-11~~

index 7c53a94106169..fb69ffa21132a 100644
@@ -432,23 +432,18 @@ static int hidinput_scale_battery_capacity(struct hid_device *dev,
 
 static int hidinput_query_battery_capacity(struct hid_device *dev)
 {
-	u8 *buf;
 	int ret;
 
-	buf = kmalloc(4, GFP_KERNEL);
+	u8 *buf __free(kfree) = kmalloc(4, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
 	ret = hid_hw_raw_request(dev, dev->battery_report_id, buf, 4,
 				 dev->battery_report_type, HID_REQ_GET_REPORT);
-	if (ret < 2) {
-		kfree(buf);
+	if (ret < 2)
 		return -ENODATA;
-	}
 
-	ret = hidinput_scale_battery_capacity(dev, buf[1]);
-	kfree(buf);
-	return ret;
+	return hidinput_scale_battery_capacity(dev, buf[1]);
 }
 
 static int hidinput_get_battery_property(struct power_supply *psy,

@@ -1811,7 +1806,6 @@ static void hidinput_led_worker(struct work_struct *work)
 	struct hid_report *report;
 	int ret;
 	u32 len;
-	__u8 *buf;
 
 	field = hidinput_get_led_field(hid);
 	if (!field)

@@ -1838,7 +1832,7 @@ static void hidinput_led_worker(struct work_struct *work)
 
 	/* fall back to generic raw-output-report */
 	len = hid_report_len(report);
-	buf = hid_alloc_report_buf(report, GFP_KERNEL);
+	u8 *buf __free(kfree) = hid_alloc_report_buf(report, GFP_KERNEL);
 	if (!buf)
 		return;

@@ -1848,7 +1842,6 @@ static void hidinput_led_worker(struct work_struct *work)
 	if (ret == -ENOSYS)
 		hid_hw_raw_request(hid, report->id, buf, len, HID_OUTPUT_REPORT,
 				HID_REQ_SET_REPORT);
-	kfree(buf);
 }
 
 static int hidinput_input_event(struct input_dev *dev, unsigned int type,

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-08-26 18:03 UTC #2 lore raw

PATCH 2/3 HID: input: Introduce struct hid_battery and refactor battery code

From: Lucas Zampieri <[email protected]>

[ Upstream commit 7a3ac62473f2bd213557e41aaab7a8f144037dfd ]

Introduce struct hid_battery to encapsulate individual battery state, preparing for future multi-battery support.

The new structure contains all battery-related fields previously stored directly in hid_device (capacity, min, max, report_type, report_id, charge_status, etc.). The hid_device->battery pointer type changes from struct power_supply* to struct hid_battery*, and all battery functions are refactored accordingly.

A hid_get_battery() helper is added for external drivers, with hid-apple.c and hid-magicmouse.c updated to use the new API. The hid-input-test.c KUnit tests are also updated for the new structure.

No functional changes for single-battery devices.

Signed-off-by Lucas Zampieri <[email protected]>

Signed-off-by Benjamin Tissoires <[email protected]>

Stable-dep-of: d07644524b65 ("HID: input: read battery capacity from its actual report offset")

Signed-off-by Sasha Levin <[email protected]>

---
 drivers/hid/hid-apple.c      |  10 +--
 drivers/hid/hid-input-test.c |  39 ++++++-----
 drivers/hid/hid-input.c      | 128 ++++++++++++++++++++---------------
 drivers/hid/hid-magicmouse.c |  10 +--
 include/linux/hid.h          |  49 ++++++++++----
 5 files changed, 143 insertions(+), 93 deletions(-)

drivers/hid/hid-apple.c +6 -4

index 742ff0c86e0f9..82cb36901e517 100644
@@ -545,17 +545,19 @@ static int apple_fetch_battery(struct hid_device *hdev)
 	struct apple_sc *asc = hid_get_drvdata(hdev);
 	struct hid_report_enum *report_enum;
 	struct hid_report *report;
+	struct hid_battery *bat;
 
-	if (!(asc->quirks & APPLE_RDESC_BATTERY) || !hdev->battery)
+	bat = hid_get_battery(hdev);
+	if (!(asc->quirks & APPLE_RDESC_BATTERY) || !bat)
 		return -1;
 
-	report_enum = &hdev->report_enum[hdev->battery_report_type];
-	report = report_enum->report_id_hash[hdev->battery_report_id];
+	report_enum = &hdev->report_enum[bat->report_type];
+	report = report_enum->report_id_hash[bat->report_id];
 
 	if (!report || report->maxfield < 1)
 		return -1;
 
-	if (hdev->battery_capacity == hdev->battery_max)
+	if (bat->capacity == bat->max)
 		return -1;
 
 	hid_hw_request(hdev, report, HID_REQ_GET_REPORT);

drivers/hid/hid-input-test.c +22 ~~-17~~

index 6f5c71660d823..c92008dafddfd 100644
@@ -9,54 +9,59 @@
 
 static void hid_test_input_update_battery_charge_status(struct kunit *test)
 {
-	struct hid_device *dev;
+	struct hid_battery *bat;
 	bool handled;
 
-	dev = kunit_kzalloc(test, sizeof(*dev), GFP_KERNEL);
-	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+	bat = kunit_kzalloc(test, sizeof(*bat), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bat);
 
-	handled = hidinput_update_battery_charge_status(dev, HID_DG_HEIGHT, 0);
+	handled = hidinput_update_battery_charge_status(bat, HID_DG_HEIGHT, 0);
 	KUNIT_EXPECT_FALSE(test, handled);
-	KUNIT_EXPECT_EQ(test, dev->battery_charge_status, POWER_SUPPLY_STATUS_UNKNOWN);
+	KUNIT_EXPECT_EQ(test, bat->charge_status, POWER_SUPPLY_STATUS_UNKNOWN);
 
-	handled = hidinput_update_battery_charge_status(dev, HID_BAT_CHARGING, 0);
+	handled = hidinput_update_battery_charge_status(bat, HID_BAT_CHARGING, 0);
 	KUNIT_EXPECT_TRUE(test, handled);
-	KUNIT_EXPECT_EQ(test, dev->battery_charge_status, POWER_SUPPLY_STATUS_DISCHARGING);
+	KUNIT_EXPECT_EQ(test, bat->charge_status, POWER_SUPPLY_STATUS_DISCHARGING);
 
-	handled = hidinput_update_battery_charge_status(dev, HID_BAT_CHARGING, 1);
+	handled = hidinput_update_battery_charge_status(bat, HID_BAT_CHARGING, 1);
 	KUNIT_EXPECT_TRUE(test, handled);
-	KUNIT_EXPECT_EQ(test, dev->battery_charge_status, POWER_SUPPLY_STATUS_CHARGING);
+	KUNIT_EXPECT_EQ(test, bat->charge_status, POWER_SUPPLY_STATUS_CHARGING);
 }
 
 static void hid_test_input_get_battery_property(struct kunit *test)
 {
 	struct power_supply *psy;
+	struct hid_battery *bat;
 	struct hid_device *dev;
 	union power_supply_propval val;
 	int ret;
 
 	dev = kunit_kzalloc(test, sizeof(*dev), GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
-	dev->battery_avoid_query = true;
+
+	bat = kunit_kzalloc(test, sizeof(*bat), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bat);
+	bat->dev = dev;
+	bat->avoid_query = true;
 
 	psy = kunit_kzalloc(test, sizeof(*psy), GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, psy);
-	psy->drv_data = dev;
+	psy->drv_data = bat;
 
-	dev->battery_status = HID_BATTERY_UNKNOWN;
-	dev->battery_charge_status = POWER_SUPPLY_STATUS_CHARGING;
+	bat->status = HID_BATTERY_UNKNOWN;
+	bat->charge_status = POWER_SUPPLY_STATUS_CHARGING;
 	ret = hidinput_get_battery_property(psy, POWER_SUPPLY_PROP_STATUS, &val);
 	KUNIT_EXPECT_EQ(test, ret, 0);
 	KUNIT_EXPECT_EQ(test, val.intval, POWER_SUPPLY_STATUS_UNKNOWN);
 
-	dev->battery_status = HID_BATTERY_REPORTED;
-	dev->battery_charge_status = POWER_SUPPLY_STATUS_CHARGING;
+	bat->status = HID_BATTERY_REPORTED;
+	bat->charge_status = POWER_SUPPLY_STATUS_CHARGING;
 	ret = hidinput_get_battery_property(psy, POWER_SUPPLY_PROP_STATUS, &val);
 	KUNIT_EXPECT_EQ(test, ret, 0);
 	KUNIT_EXPECT_EQ(test, val.intval, POWER_SUPPLY_STATUS_CHARGING);
 
-	dev->battery_status = HID_BATTERY_REPORTED;
-	dev->battery_charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
+	bat->status = HID_BATTERY_REPORTED;
+	bat->charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
 	ret = hidinput_get_battery_property(psy, POWER_SUPPLY_PROP_STATUS, &val);
 	KUNIT_EXPECT_EQ(test, ret, 0);
 	KUNIT_EXPECT_EQ(test, val.intval, POWER_SUPPLY_STATUS_DISCHARGING);

drivers/hid/hid-input.c +72 ~~-56~~

256 lines not on this page · raw message

drivers/hid/hid-magicmouse.c +6 -4

index d5df2745f3da4..f5d0a280e12ef 100644
@@ -797,19 +797,21 @@ static int magicmouse_fetch_battery(struct hid_device *hdev)
 #ifdef CONFIG_HID_BATTERY_STRENGTH
 	struct hid_report_enum *report_enum;
 	struct hid_report *report;
+	struct hid_battery *bat;
 
-	if (!hdev->battery ||
+	bat = hid_get_battery(hdev);
+	if (!bat ||
 	    (!is_usb_magicmouse2(hdev->vendor, hdev->product) &&
 	     !is_usb_magictrackpad2(hdev->vendor, hdev->product)))
 		return -1;
 
-	report_enum = &hdev->report_enum[hdev->battery_report_type];
-	report = report_enum->report_id_hash[hdev->battery_report_id];
+	report_enum = &hdev->report_enum[bat->report_type];
+	report = report_enum->report_id_hash[bat->report_id];
 
 	if (!report || report->maxfield < 1)
 		return -1;
 
-	if (hdev->battery_capacity == hdev->battery_max)
+	if (bat->capacity == bat->max)
 		return -1;
 
 	hid_hw_request(hdev, report, HID_REQ_GET_REPORT);

include/linux/hid.h +37 ~~-12~~

68 lines not on this page · raw message

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-08-26 18:03 UTC #3 lore raw

PATCH 3/3 HID: input: read battery capacity from its actual report offset

In reply to Sasha Levin

From: Jose Villaseñor Montfort <[email protected]>

[ Upstream commit d07644524b6511b622ee7b0e2e68c9ee43d522a4 ]

hidinput_query_battery_capacity() assumes the state-of-charge value is the first byte following the report ID (buf[1]) and ignores where the battery field actually sits within the report.

An Apple Magic Trackpad 2 precedes the AbsoluteStateOfCharge byte with a byte of status flags in its battery reports, so this query returns the flags byte instead of the charge level.

  hid-<serial>-battery-144 = 100%  (Charging)      <- report event path
  hid-<serial>-battery-155 =   3%  (Discharging)   <- query path

Both are the same physical battery. A raw HIDIOCGINPUT of the two reports at that same moment:

report 0x90 -> [90 03 64]
report 0x9b -> [9b 03 64 64 00 00 10 00 00 00 00 00 00 00]

                     ^flags ^SoC = 0x64 = 100%

The device answers correctly in both cases; only the offset the kernel reads the capacity from is wrong. 0x03 is the flags byte (present, charging), reported as "3%".

Bluetooth takes the same query path for its capacity, where the trackpad reported a bogus near-constant ~4% -- 0b100, the FullyCharged flag -- regardless of the real charge.

Devices whose capacity field is the first field in the report have a report_offset of 0 and are unaffected (buf[1 + 0] == buf[1]).

Fixes 581c4484769e ("HID: input: map digitizer battery usage")

Cc [email protected]

Signed-off-by Jose Villaseñor Montfort <[email protected]>

Reviewed-by Alec Hall <[email protected]>

Signed-off-by Jiri Kosina <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

---
 drivers/hid/hid-input.c | 17 +++++++++++++----
 include/linux/hid.h     |  2 ++
 2 files changed, 15 insertions(+), 4 deletions(-)

drivers/hid/hid-input.c +13 -4

index fbf882c693e9b..eb10681a1afc6 100644
@@ -433,17 +433,25 @@ static int hidinput_scale_battery_capacity(struct hid_battery *bat,
 static int hidinput_query_battery_capacity(struct hid_battery *bat)
 {
 	int ret;
+	/*
+	 * The capacity field may not be the first field in the report: some
+	 * devices (e.g. the Apple Magic Trackpad 2 over Bluetooth) precede it
+	 * with status flags. Read it from its actual byte offset in the report
+	 * (report_offset is in bits; the leading byte is the report id).
+	 */
+	int offset = 1 + bat->report_offset / 8;
+	int len = offset + 1;
 
-	u8 *buf __free(kfree) = kmalloc(4, GFP_KERNEL);
+	u8 *buf __free(kfree) = kmalloc(max(len, 4), GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
-	ret = hid_hw_raw_request(bat->dev, bat->report_id, buf, 4,
+	ret = hid_hw_raw_request(bat->dev, bat->report_id, buf, max(len, 4),
 				 bat->report_type, HID_REQ_GET_REPORT);
-	if (ret < 2)
+	if (ret < len)
 		return -ENODATA;
 
-	return hidinput_scale_battery_capacity(bat, buf[1]);
+	return hidinput_scale_battery_capacity(bat, buf[offset]);
 }
 
 static int hidinput_get_battery_property(struct power_supply *psy,

@@ -568,6 +576,7 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
 	bat->max = max;
 	bat->report_type = report_type;
 	bat->report_id = field->report->id;
+	bat->report_offset = field->report_offset;
 	bat->charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
 	bat->status = HID_BATTERY_UNKNOWN;

include/linux/hid.h +2 -0

index c5b16ea59fad6..9d1da2ef208ce 100644
@@ -608,6 +608,7 @@ enum hid_battery_status {
  * @max: maximum battery value from HID descriptor
  * @report_type: HID report type (input/feature)
  * @report_id: HID report ID for this battery
+ * @report_offset: bit offset of the capacity field within its report
  * @charge_status: current charging status
  * @status: battery reporting status
  * @capacity: current battery capacity (0-100)

@@ -621,6 +622,7 @@ struct hid_battery {
 	__s32 max;
 	__s32 report_type;
 	__s32 report_id;
+	__s32 report_offset;
 	__s32 charge_status;
 	enum hid_battery_status status;
 	__s32 capacity;

Signature · 1 line

2.53.0