From d0612f906d565c2cd416d095405677d11384ec36 Mon Sep 17 00:00:00 2001
From: amtz <1207020+amtz@users.noreply.github.com>
Date: Mon, 2 Aug 2021 12:55:40 +0200
Subject: [PATCH] Limit udev device scan to subsystem 'input'

This change makes the call to 'udev_enumerate_scan_devices' much faster.
In particular, for some bluetooth devices, this function may implicitly
read its battery's virtual file 'uevent', e.g.

/sys/devices/*/usb1/1-1/*/bluetooth/hci0/*/power_supply/hid-*-battery/uevent

Reading this file may (for unknown reasons) block up to 10 seconds.
Since udev_enumerate_scan_devices is called 4 times (for keyboard,
mouse, touchpad, and joypad) during startup this may cause a
considerable delay.

Limiting the scan to subsystem 'input' yields the same devices but makes
the scan faster and does not read 'uevent' of the input controller's
power_supply.
---
 input/drivers/udev_input.c         | 1 +
 input/drivers_joypad/udev_joypad.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/input/drivers/udev_input.c b/input/drivers/udev_input.c
index 979425f69c..36409fc6bf 100644
--- a/input/drivers/udev_input.c
+++ b/input/drivers/udev_input.c
@@ -1234,6 +1234,7 @@ static bool open_devices(udev_input_t *udev,
       return false;
 
    udev_enumerate_add_match_property(enumerate, type_str, "1");
+   udev_enumerate_add_match_subsystem(enumerate, "input");
    udev_enumerate_scan_devices(enumerate);
    devs = udev_enumerate_get_list_entry(enumerate);
 
diff --git a/input/drivers_joypad/udev_joypad.c b/input/drivers_joypad/udev_joypad.c
index 4b985f1953..bac970fb5d 100644
--- a/input/drivers_joypad/udev_joypad.c
+++ b/input/drivers_joypad/udev_joypad.c
@@ -574,6 +574,7 @@ static void *udev_joypad_init(void *data)
       goto error;
 
    udev_enumerate_add_match_property(enumerate, "ID_INPUT_JOYSTICK", "1");
+   udev_enumerate_add_match_subsystem(enumerate, "input");
    udev_enumerate_scan_devices(enumerate);
    devs = udev_enumerate_get_list_entry(enumerate);