linux-kernel - [PATCH AUTOSEL 5.10 009/217] HID: hid-input: occasionally report stylus battery even if not changed

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Date:   Tue, 22 Dec 2020 21:12:58 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     "dmitry.torokhov@...il.com" <dmitry.torokhov@...il.com>,
        Jiri Kosina <jkosina@...e.cz>, Sasha Levin <sashal@...nel.org>,
        linux-input@...r.kernel.org
Subject: [PATCH AUTOSEL 5.10 009/217] HID: hid-input: occasionally report stylus battery even if not changed

From: "dmitry.torokhov@...il.com" <dmitry.torokhov@...il.com>

[ Upstream commit c6838eeef2fbc7e3e1f83759aa016ae6b70c643e ]

There are styluses that only report their battery status when they are
touching the touchscreen; additionally we currently suppress battery
reports if capacity has not changed. To help userspace recognize how long
ago the device reported battery status, let's send the change event through
if either capacity has changed, or at least 30 seconds have passed since
last report we've let through.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/hid/hid-input.c | 5 ++++-
 include/linux/hid.h     | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 4dca113924593..f797659cb9d91 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -537,9 +537,12 @@ static void hidinput_update_battery(struct hid_device *dev, int value)
 	capacity = hidinput_scale_battery_capacity(dev, value);
 
 	if (dev->battery_status != HID_BATTERY_REPORTED ||
-	    capacity != dev->battery_capacity) {
+	    capacity != dev->battery_capacity ||
+	    ktime_after(ktime_get_coarse(), dev->battery_ratelimit_time)) {
 		dev->battery_capacity = capacity;
 		dev->battery_status = HID_BATTERY_REPORTED;
+		dev->battery_ratelimit_time =
+			ktime_add_ms(ktime_get_coarse(), 30 * 1000);
 		power_supply_changed(dev->battery);
 	}
 }
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 58684657960bf..b079146850e6e 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -585,6 +585,7 @@ struct hid_device {							/* device report descriptor */
 	__s32 battery_report_id;
 	enum hid_battery_status battery_status;
 	bool battery_avoid_query;
+	ktime_t battery_ratelimit_time;
 #endif
 
 	unsigned long status;						/* see STAT flags above */
-- 
2.27.0