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backlight: read current backlight brightness from 'actual_brightness' attribute 

Closes #16302.
This commit is contained in:
Yu Watanabe 2020-06-30 19:41:39 +09:00
parent daa227a320
commit 437b9a7f75
1 changed files with 32 additions and 4 deletions
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36
src/backlight/backlight.c
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@ -297,6 +297,34 @@ static bool shall_clamp(sd_device *d) {
return r;
}
static int read_brightness(sd_device *device, const char **ret) {
const char *subsystem;
int r;
assert(device);
assert(ret);
r = sd_device_get_subsystem(device, &subsystem);
if (r < 0)
return log_device_debug_errno(device, r, "Failed to get subsystem: %m");
if (streq(subsystem, "backlight")) {
r = sd_device_get_sysattr_value(device, "actual_brightness", ret);
if (r >= 0)
return 0;
if (r != -ENOENT)
return log_device_debug_errno(device, r, "Failed to read 'actual_brightness' attribute: %m");
log_device_debug_errno(device, r, "Failed to read 'actual_brightness' attribute, fall back to use 'brightness' attribute: %m");
}
r = sd_device_get_sysattr_value(device, "brightness", ret);
if (r < 0)
return log_device_debug_errno(device, r, "Failed to read 'brightness' attribute: %m");
return 0;
}
static int run(int argc, char *argv[]) {
_cleanup_(sd_device_unrefp) sd_device *device = NULL;
_cleanup_free_ char *escaped_ss = NULL, *escaped_sysname = NULL, *escaped_path_id = NULL;
@ -383,9 +411,9 @@ static int run(int argc, char *argv[]) {
if (!clamp)
return 0;
r = sd_device_get_sysattr_value(device, "brightness", &curval);
r = read_brightness(device, &curval);
if (r < 0)
return log_device_warning_errno(device, r, "Failed to read 'brightness' attribute: %m");
return log_device_error_errno(device, r, "Failed to read current brightness: %m");
value = strdup(curval);
if (!value)
@ -408,9 +436,9 @@ static int run(int argc, char *argv[]) {
return 0;
}
r = sd_device_get_sysattr_value(device, "brightness", &value);
r = read_brightness(device, &value);
if (r < 0)
return log_device_error_errno(device, r, "Failed to read system 'brightness' attribute: %m");
return log_device_error_errno(device, r, "Failed to read current brightness: %m");
r = write_string_file(saved, value, WRITE_STRING_FILE_CREATE);
if (r < 0)