linux-kernel - [PATCH] HID: input: do not report stylus battery state as "full"

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Message-ID: <YNtlrrKZVQY4byVa@google.com>
Date:   Tue, 29 Jun 2021 11:25:50 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Kenneth Albanowski <kenalba@...gle.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] HID: input: do not report stylus battery state as "full"

The power supply states of discharging, charging, full, etc, represent
state of charging, not the capacity level of the battery (for which
we have a separate property). Current HID usage tables to not allow
for expressing charging state of the batteries found in generic
styli, so we should simply assume that the battery is discharging
even if current capacity is at 100% when battery strength reporting
is done via HID interface. In fact, we were doing just that before
commit 581c4484769e.

This change helps UIs to not mis-represent fully charged batteries in
styli as being charging/topping-off.

Fixes: 581c4484769e ("HID: input: map digitizer battery usage")
Reported-by: Kenneth Albanowski <kenalba@...gle.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
 drivers/hid/hid-input.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index e982d8173c9c..e85a1a34ff39 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -417,8 +417,6 @@ static int hidinput_get_battery_property(struct power_supply *psy,

 		if (dev->battery_status == HID_BATTERY_UNKNOWN)
 			val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
-		else if (dev->battery_capacity == 100)
-			val->intval = POWER_SUPPLY_STATUS_FULL;
 		else
 			val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
 		break;
-- 
2.32.0.93.g670b81a890-goog

-- 
Dmitry