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backlight: reindent comments

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This commit is contained in:
Yu Watanabe 2021-02-22 23:45:55 +09:00
parent d17d66f0ab
commit b77c929934
1 changed files with 22 additions and 32 deletions
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54
src/backlight/backlight.c
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@ -135,19 +135,14 @@ static int validate_device(sd_device *device) {
assert(device);
/* Verify whether we should actually care for a specific
* backlight device. For backlight devices there might be
* multiple ways to access the same control: "firmware"
* (i.e. ACPI), "platform" (i.e. via the machine's EC) and
* "raw" (via the graphics card). In general we should prefer
* "firmware" (i.e. ACPI) or "platform" access over "raw"
* access, in order not to confuse the BIOS/EC, and
* compatibility with possible low-level hotkey handling of
* screen brightness. The kernel will already make sure to
* expose only one of "firmware" and "platform" for the same
* device to userspace. However, we still need to make sure
* that we use "raw" only if no "firmware" or "platform"
* device for the same device exists. */
/* Verify whether we should actually care for a specific backlight device. For backlight devices
* there might be multiple ways to access the same control: "firmware" (i.e. ACPI), "platform"
* (i.e. via the machine's EC) and "raw" (via the graphics card). In general we should prefer
* "firmware" (i.e. ACPI) or "platform" access over "raw" access, in order not to confuse the
* BIOS/EC, and compatibility with possible low-level hotkey handling of screen brightness. The
* kernel will already make sure to expose only one of "firmware" and "platform" for the same
* device to userspace. However, we still need to make sure that we use "raw" only if no
* "firmware" or "platform" device for the same device exists. */
r = sd_device_get_subsystem(device, &subsystem);
if (r < 0)
@ -192,9 +187,8 @@ static int validate_device(sd_device *device) {
!STR_IN_SET(v, "platform", "firmware"))
continue;
/* OK, so there's another backlight device, and it's a
* platform or firmware device, so, let's see if we
* can verify it belongs to the same device as ours. */
/* OK, so there's another backlight device, and it's a platform or firmware device.
* Let's see if we can verify it belongs to the same device as ours. */
if (find_pci_or_platform_parent(other, &other_parent) < 0)
continue;
@ -255,11 +249,6 @@ static int get_max_brightness(sd_device *device, unsigned *ret) {
return 0;
}
/* 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 in case of 'backlight' subsystem. This avoids preserving
* an unreadably dim screen, which would otherwise force the user to
* disable state restoration. */
static int clamp_brightness(sd_device *device, bool saved, unsigned max_brightness, unsigned *brightness) {
unsigned new_brightness, min_brightness;
const char *subsystem;
@ -268,6 +257,11 @@ static int clamp_brightness(sd_device *device, bool saved, unsigned max_brightne
assert(device);
assert(brightness);
/* Some systems turn the backlight all the way off at the lowest levels. This clamps the saved
* brightness to at least 1 or 5% of max_brightness in case of 'backlight' subsystem. This
* avoids preserving an unreadably dim screen, which would otherwise force the user to disable
* state restoration. */
r = sd_device_get_subsystem(device, &subsystem);
if (r < 0)
return log_device_warning_errno(device, r, "Failed to get device subsystem: %m");
@ -410,9 +404,8 @@ static int run(int argc, char *argv[]) {
if (r < 0)
return log_error_errno(r, "Failed to get backlight or LED device '%s:%s': %m", ss, sysname);
/* If max_brightness is 0, then there is no actual backlight
* device. This happens on desktops with Asus mainboards
* that load the eeepc-wmi module. */
/* If max_brightness is 0, then there is no actual backlight device. This happens on desktops
* with Asus mainboards that load the eeepc-wmi module. */
if (get_max_brightness(device, &max_brightness) < 0)
return 0;
@ -433,14 +426,11 @@ static int run(int argc, char *argv[]) {
} else
saved = strjoina("/var/lib/systemd/backlight/", escaped_ss, ":", escaped_sysname);
/* If there are multiple conflicting backlight devices, then
* their probing at boot-time might happen in any order. This
* means the validity checking of the device then is not
* reliable, since it might not see other devices conflicting
* with a specific backlight. To deal with this, we will
* actively delete backlight state files at shutdown (where
* device probing should be complete), so that the validity
* check at boot time doesn't have to be reliable. */
/* If there are multiple conflicting backlight devices, then their probing at boot-time might
* happen in any order. This means the validity checking of the device then is not reliable,
* since it might not see other devices conflicting with a specific backlight. To deal with
* this, we will actively delete backlight state files at shutdown (where device probing should
* be complete), so that the validity check at boot time doesn't have to be reliable. */
if (streq(argv[1], "load")) {
_cleanup_free_ char *value = NULL;