How to control power of a device from sysfs ?
Hello, I am trying to turn off screen using sysfs entries, but I'm having some difficulties with it: 1. command: echo 0 > /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/brightness result: screen is dimmed - BUT not turned off 2. command: cat /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/actual_brightness 20 This strengthen the fast that we didn't turned off brightness completely 3. In this point I though that maybe I can turn off the whole brightness device ls /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/ actual_brightness auto_brightness bl_power brightness device dimming max_brightness power subsystem type uevent I made some trials , but didn't made it turned off yet. Is there any idea if it's possible to turn it off completely ? Thank you, Ran
On Mon, Dec 5, 2016 at 12:56 PM, Ran Shalit <ranshalit@gmail.com> wrote:
Hello,
I am trying to turn off screen using sysfs entries, but I'm having some difficulties with it:
1. command: echo 0 > /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/brightness result: screen is dimmed - BUT not turned off
2. command: cat /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/actual_brightness 20
This strengthen the fast that we didn't turned off brightness completely
3. In this point I though that maybe I can turn off the whole brightness device
ls /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/ actual_brightness auto_brightness bl_power brightness device dimming max_brightness power subsystem type uevent
I made some trials , but didn't made it turned off yet. Is there any idea if it's possible to turn it off completely ?
In my opinion, you'll need to have a look into the driver's code. See if that exposes a mechanism to turn off the screen at all. - Umair
On Mon, Dec 5, 2016 at 10:24 AM, Umair Khan <omerjerk@gmail.com> wrote:
On Mon, Dec 5, 2016 at 12:56 PM, Ran Shalit <ranshalit@gmail.com> wrote:
Hello,
I am trying to turn off screen using sysfs entries, but I'm having some difficulties with it:
1. command: echo 0 > /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/ brightness result: screen is dimmed - BUT not turned off
2. command: cat /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/ actual_brightness 20
This strengthen the fast that we didn't turned off brightness completely
3. In this point I though that maybe I can turn off the whole brightness device
ls /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/ actual_brightness auto_brightness bl_power brightness device dimming max_brightness power subsystem type uevent
I made some trials , but didn't made it turned off yet. Is there any idea if it's possible to turn it off completely ?
In my opinion, you'll need to have a look into the driver's code. See if that exposes a mechanism to turn off the screen at all.
Right, Seems that sysfs exports features that drivers might not support (or supported differently between different drivers) for ea8061 driver: Yet, not sure why on setting brightness 0 , I get that that it that "catual_brightness" is 20. See ea8061_set_brightness below. https://github.com/gokhanmoral/siyahkernel-sgs3/blob/master-3.0.31/drivers/v... static int ea8061_set_brightness(struct backlight_device *bd) { int ret = 0, brightness = bd->props.brightness; struct ea8061 *lcd = bl_get_data(bd); if (lcd->power == FB_BLANK_POWERDOWN) { dev_err(lcd->dev, "lcd off: brightness set failed.\n"); return -EINVAL; } if (brightness < MIN_BRIGHTNESS || brightness > bd->props.max_brightness) { dev_err(lcd->dev, "lcd brightness should be %d to %d.\n", MIN_BRIGHTNESS, MAX_BRIGHTNESS); return -EINVAL; } ret = ea8061_gamma_ctrl(lcd, brightness); if (ret) { dev_err(&bd->dev, "lcd brightness setting failed.\n"); return -EIO; } return ret; } Thanks, Ran - Umair
On Mon, Dec 05, 2016 at 09:26:27AM +0200, Ran Shalit wrote:
Hello,
I am trying to turn off screen using sysfs entries, but I'm having some difficulties with it:
1. command: echo 0 > /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/brightness result: screen is dimmed - BUT not turned off
2. command: cat /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/actual_brightness 20
This strengthen the fast that we didn't turned off brightness completely
3. In this point I though that maybe I can turn off the whole brightness device
ls /sys/devices/platform/s5p-dsim.0/ea8061/backlight/panel/ actual_brightness auto_brightness bl_power brightness device dimming max_brightness power subsystem type uevent
I made some trials , but didn't made it turned off yet. Is there any idea if it's possible to turn it off completely ?
If the driver supports power management, then you can control the power state with the power/runtime_status sysfs entry. Some of the sysfs entries in the power/ directory are documented in Documentation/ABI/testing/sysfs-devices-power. Brian
participants (3)
-
Brian Masney -
Ran Shalit -
Umair Khan