[PATCH v2] selftests/hid: test battery queries with nonzero field offsets

[Mason Camara <ping@masoncamara.com>]

Commit d07644524b65 ("HID: input: read battery capacity from its actual
report offset") fixed synchronous battery queries for reports that place
the capacity byte after status fields.

Add a UHID mouse with the Magic Mouse 2 report layout and answer GET_REPORT
with 90 04 5f. Read capacity before sending an input report so the test
exercises the synchronous query path. Without the fix, it reads the status
byte as 4%; with the fix, it reads capacity as 95%.

Enable CONFIG_HID_BATTERY_STRENGTH in the HID selftest configuration.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=221263
Assisted-by: LLM
Signed-off-by: Mason Camara <ping@masoncamara.com>
---

Changes in v2:
- Drop driver fix, superseded by d07644524b65.
- Rebase the regression test onto the current HID for-next branch.
- Amend commit message and tool-assistance trailer.

v1: https://lore.kernel.org/linux-input/20260712044702.893825-1-ping@masoncamara.com/

 tools/testing/selftests/hid/config            |  1 +
 .../testing/selftests/hid/tests/test_mouse.py | 54 +++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/tools/testing/selftests/hid/config b/tools/testing/selftests/hid/config
index 1758b055f..da52335b8 100644
--- a/tools/testing/selftests/hid/config
+++ b/tools/testing/selftests/hid/config
@@ -16,6 +16,7 @@ CONFIG_FTRACE_SYSCALLS=y
 CONFIG_FUNCTION_TRACER=y
 CONFIG_HIDRAW=y
 CONFIG_HID=y
+CONFIG_HID_BATTERY_STRENGTH=y
 CONFIG_HID_BPF=y
 CONFIG_INPUT_EVDEV=y
 CONFIG_UHID=y
diff --git a/tools/testing/selftests/hid/tests/test_mouse.py b/tools/testing/selftests/hid/tests/test_mouse.py
index eb4e15a0e..141c1f069 100644
--- a/tools/testing/selftests/hid/tests/test_mouse.py
+++ b/tools/testing/selftests/hid/tests/test_mouse.py
@@ -11,6 +11,7 @@ import hidtools.hid
 from hidtools.util import BusType
 import libevdev
 import logging
+import threading
 import pytest
 
 logger = logging.getLogger("hidtools.test.mouse")
@@ -598,6 +599,35 @@ class ResolutionMultiplierHWheelMouse(TwoWheelMouse):
         return 0
 
 
+class BatteryOffsetMouse(BaseMouse):
+    report_descriptor = [
+        # Mouse report
+        0x05, 0x01, 0x09, 0x02, 0xa1, 0x01, 0x85, 0x12,
+        0x05, 0x09, 0x19, 0x01, 0x29, 0x02, 0x15, 0x00,
+        0x25, 0x01, 0x95, 0x02, 0x75, 0x01, 0x81, 0x02,
+        0x95, 0x01, 0x75, 0x06, 0x81, 0x01, 0x05, 0x01,
+        0x09, 0x01, 0xa1, 0x00, 0x09, 0x30, 0x09, 0x31,
+        0x15, 0x81, 0x25, 0x7f, 0x75, 0x08, 0x95, 0x02,
+        0x81, 0x06, 0xc0, 0xc0,
+        # Battery report: one status byte followed by capacity
+        0x06, 0x00, 0xff, 0x09, 0x14, 0xa1, 0x01, 0x85,
+        0x90, 0x05, 0x84, 0x75, 0x01, 0x95, 0x03, 0x15,
+        0x00, 0x25, 0x01, 0x09, 0x61, 0x05, 0x85, 0x09,
+        0x44, 0x09, 0x46, 0x81, 0x02, 0x95, 0x05, 0x81,
+        0x01, 0x75, 0x08, 0x95, 0x01, 0x15, 0x00, 0x26,
+        0xff, 0x00, 0x09, 0x65, 0x81, 0x02, 0xc0,
+    ]
+
+    def __init__(self, rdesc=report_descriptor, name=None, input_info=None):
+        super().__init__(rdesc, name, input_info)
+
+    def get_report(self, req, rnum, rtype):
+        if rtype != self.UHID_INPUT_REPORT or rnum != 0x90:
+            return (1, [])
+
+        return (0, [0x90, 0x04, 0x5F])
+
+
 class BaseTest:
     class TestMouse(base.BaseTestCase.TestUhid):
         def test_buttons(self):
@@ -1045,3 +1075,27 @@ class TestBadReportDescriptorMouse(base.BaseTestCase.TestUhid):
 
     def assertName(self, uhdev):
         pass
+
+
+class TestBatteryOffsetMouse(base.BaseTestCase.TestUhid):
+    def create_device(self):
+        return BatteryOffsetMouse()
+
+    def test_queried_battery_field_offset(self):
+        uhdev = self.uhdev
+        power_supply = uhdev.power_supply_class
+        assert power_supply is not None
+
+        done = False
+
+        def dispatch():
+            while not done:
+                uhdev.dispatch(1)
+
+        thread = threading.Thread(target=dispatch)
+        thread.start()
+        try:
+            assert power_supply.capacity == 95
+        finally:
+            done = True
+            thread.join()

base-commit: 931aaa59d1826f43b0bb3f07e21233f6faf4540a
-- 
2.39.5 (Apple Git-154)