X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fbacklight%2Fbacklight.c;h=ab05a7d1a7ae3501bcb5259387e8907efdbddfc3;hp=754a646c3d433690e1c334dfe823422abbaca7ea;hb=0a1beeb64207eaa88ab9236787b1cbc2f704ae14;hpb=938d2699d2e818bd996614e89ea3d668200ad2a8

diff --git a/src/backlight/backlight.c b/src/backlight/backlight.c
index 754a646c3..ab05a7d1a 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_errno(-r, "Failed to parse 'max_brightness' \"%s\": %m", max_brightness_str);
+                return 0;
+        }
+
+        if (max_brightness <= 0) {
+                log_warning("Maximum brightness is 0, ignoring device.");
                 return 0;
         }
 
@@ -221,19 +225,27 @@ static unsigned get_max_brightness(struct udev_device *device) {
 
 /* Some systems turn the backlight all the way off at the lowest levels.
  * clamp_brightness clamps the saved brightness to at least 1 or 5% of
- * max_brightness.  This avoids preserving an unreadably dim screen, which
- * would otherwise force the user to disable state restoration. */
+ * max_brightness in case of 'backlight' subsystem. This avoids preserving
+ * an unreadably dim screen, which would otherwise force the user to
+ * disable state restoration. */
 static void clamp_brightness(struct udev_device *device, char **value, unsigned max_brightness) {
         int r;
-        unsigned brightness, new_brightness;
+        unsigned brightness, new_brightness, min_brightness;
+        const char *subsystem;
 
         r = safe_atou(*value, &brightness);
         if (r < 0) {
-                log_warning("Failed to parse brightness \"%s\": %s", *value, strerror(-r));
+                log_warning_errno(-r, "Failed to parse brightness \"%s\": %m", *value);
                 return;
         }
 
-        new_brightness = MAX3(brightness, 1U, max_brightness/20);
+        subsystem = udev_device_get_subsystem(device);
+        if (streq_ptr(subsystem, "backlight"))
+                min_brightness = MAX(1U, max_brightness/20);
+        else
+                min_brightness = 0;
+
+        new_brightness = CLAMP(brightness, min_brightness, max_brightness);
         if (new_brightness != brightness) {
                 char *old_value = *value;
 
@@ -243,7 +255,11 @@ static void clamp_brightness(struct udev_device *device, char **value, unsigned
                         return;
                 }
 
-                log_debug("Saved brightness %s too low; increasing to %s.", old_value, *value);
+                log_info("Saved brightness %s %s to %s.", old_value,
+                         new_brightness > brightness ?
+                         "too low; increasing" : "too high; decreasing",
+                         *value);
+
                 free(old_value);
         }
 }
@@ -356,9 +372,12 @@ int main(int argc, char *argv[]) {
          * device probing should be complete), so that the validity
          * check at boot time doesn't have to be reliable. */
 
-        if (streq(argv[1], "load") && shall_restore_state()) {
+        if (streq(argv[1], "load")) {
                 _cleanup_free_ char *value = NULL;
 
+                if (!shall_restore_state())
+                        return EXIT_SUCCESS;
+
                 if (!validate_device(udev, device))
                         return EXIT_SUCCESS;
 
@@ -368,7 +387,7 @@ int main(int argc, char *argv[]) {
                         if (r == -ENOENT)
                                 return EXIT_SUCCESS;
 
-                        log_error("Failed to read %s: %s", saved, strerror(-r));
+                        log_error_errno(-r, "Failed to read %s: %m", saved);
                         return EXIT_FAILURE;
                 }
 
@@ -397,7 +416,7 @@ int main(int argc, char *argv[]) {
 
                 r = write_string_file(saved, value);
                 if (r < 0) {
-                        log_error("Failed to write %s: %s", saved, strerror(-r));
+                        log_error_errno(-r, "Failed to write %s: %m", saved);
                         return EXIT_FAILURE;
                 }