From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 23 Apr 2014 04:55:54 +0000 (+0200)
Subject: backlight: warn if kernel exposes backlight device with bogus max_brightness
X-Git-Tag: v213~336
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=c7fdf44d08e1217d40dc092fb90a65978a0f541f;hp=e30fa16e27cbd48f960113a1d72d9a15c3b2d67b;p=elogind.git

backlight: warn if kernel exposes backlight device with bogus max_brightness

We shouldn't silently tape over broken kernel drivers.
---

diff --git a/src/backlight/backlight.c b/src/backlight/backlight.c
index 754a646c3..c70839161 100644
--- a/src/backlight/backlight.c
+++ b/src/backlight/backlight.c
@@ -205,14 +205,18 @@ static unsigned get_max_brightness(struct udev_device *device) {
 
         max_brightness_str = udev_device_get_sysattr_value(device, "max_brightness");
         if (!max_brightness_str) {
-                log_warning("Failed to read 'max_brightness' attribute");
+                log_warning("Failed to read 'max_brightness' attribute.");
                 return 0;
         }
 
         r = safe_atou(max_brightness_str, &max_brightness);
         if (r < 0) {
-                log_warning("Failed to parse 'max_brightness' \"%s\": %s",
-                            max_brightness_str, strerror(-r));
+                log_warning("Failed to parse 'max_brightness' \"%s\": %s", max_brightness_str, strerror(-r));
+                return 0;
+        }
+
+        if (max_brightness <= 0) {
+                log_warning("Maximum brightness is 0, ignoring device.");
                 return 0;
         }