forked from pool/systemd
109 lines
4.5 KiB
Diff
109 lines
4.5 KiB
Diff
From 3cadce7d33e263ec7a6a83c00c11144930258b22 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Thomas=20B=C3=A4chler?= <thomas@archlinux.org>
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Date: Thu, 27 Mar 2014 23:41:59 +0100
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Subject: [PATCH] backlight: do nothing if max_brightness is 0
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On virtually any newer Asus mainboard, the eeepc-wmi driver is loaded.
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It exposes a backlight device despite the lack of any physical backlight
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devices. This fake backlight device has max_brightness set to 0. Since
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the introduction of the clamp_brightness function, systemd-backlight
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tries to write '1' to brightness and fails.
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This patch changes systemd-backlight to exit gracefully when
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max_brightness is 0 before performing any action. This affects
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both the load and save actions.
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---
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src/backlight/backlight.c | 44 ++++++++++++++++++++++++++++++--------------
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1 file changed, 30 insertions(+), 14 deletions(-)
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diff --git src/backlight/backlight.c src/backlight/backlight.c
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index abf8bcf..ce0385b 100644
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--- src/backlight/backlight.c
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+++ src/backlight/backlight.c
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@@ -192,30 +192,37 @@ static bool validate_device(struct udev *udev, struct udev_device *device) {
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return true;
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}
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-/* Some systems turn the backlight all the way off at the lowest levels.
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- * clamp_brightness clamps the saved brightness to at least 1 or 5% of
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- * max_brightness. This avoids preserving an unreadably dim screen, which
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- * would otherwise force the user to disable state restoration. */
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-static void clamp_brightness(struct udev_device *device, char **value) {
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+static unsigned get_max_brightness(struct udev_device *device) {
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int r;
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const char *max_brightness_str;
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- unsigned brightness, max_brightness, new_brightness;
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+ unsigned max_brightness;
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max_brightness_str = udev_device_get_sysattr_value(device, "max_brightness");
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if (!max_brightness_str) {
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- log_warning("Failed to read max_brightness attribute; not checking saved brightness");
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- return;
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+ log_warning("Failed to read max_brightness attribute");
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+ return 0;
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}
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- r = safe_atou(*value, &brightness);
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+ r = safe_atou(max_brightness_str, &max_brightness);
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if (r < 0) {
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- log_warning("Failed to parse brightness \"%s\": %s", *value, strerror(-r));
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- return;
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+ log_warning("Failed to parse max_brightness \"%s\": %s", max_brightness_str, strerror(-r));
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+ return 0;
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}
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- r = safe_atou(max_brightness_str, &max_brightness);
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+ return max_brightness;
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+}
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+
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+/* Some systems turn the backlight all the way off at the lowest levels.
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+ * clamp_brightness clamps the saved brightness to at least 1 or 5% of
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+ * max_brightness. This avoids preserving an unreadably dim screen, which
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+ * would otherwise force the user to disable state restoration. */
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+static void clamp_brightness(struct udev_device *device, char **value, unsigned max_brightness) {
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+ int r;
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+ unsigned brightness, new_brightness;
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+
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+ r = safe_atou(*value, &brightness);
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if (r < 0) {
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- log_warning("Failed to parse max_brightness \"%s\": %s", max_brightness_str, strerror(-r));
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+ log_warning("Failed to parse brightness \"%s\": %s", *value, strerror(-r));
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return;
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}
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@@ -239,6 +246,7 @@ int main(int argc, char *argv[]) {
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_cleanup_udev_device_unref_ struct udev_device *device = NULL;
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_cleanup_free_ char *saved = NULL, *ss = NULL, *escaped_ss = NULL, *escaped_sysname = NULL, *escaped_path_id = NULL;
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const char *sysname, *path_id;
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+ unsigned max_brightness;
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int r;
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if (argc != 3) {
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@@ -294,6 +302,14 @@ int main(int argc, char *argv[]) {
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return EXIT_FAILURE;
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}
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+ /* If max_brightness is 0, then there is no actual backlight
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+ * device. This happens on desktops with Asus mainboards
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+ * that load the eeepc-wmi module.
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+ */
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+ max_brightness = get_max_brightness(device);
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+ if (max_brightness == 0)
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+ return EXIT_SUCCESS;
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+
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escaped_ss = cescape(ss);
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if (!escaped_ss) {
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log_oom();
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@@ -348,7 +364,7 @@ int main(int argc, char *argv[]) {
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return EXIT_FAILURE;
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}
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- clamp_brightness(device, &value);
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+ clamp_brightness(device, &value, max_brightness);
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r = udev_device_set_sysattr_value(device, "brightness", value);
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if (r < 0) {
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--
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1.7.9.2
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