Intel HD Haswell > Chrontel CH7511b, backlight brightness control (solved)

[cj147]

Hi Anyone,

I have an touch panel PC from China, model SK_K12DR, with Intel HD Haswell & Chrontel CH7511b display controller.

Using Windows 10, the backlight brightness can be adjusted by Intel HD driver application.

However, in FossaPup (kernel 5.4.53), the brightness can't seem to be controlled (not just adjust the gamma values which doesn't really change the brightness).

Is this an outstanding issue with Linux i915 & Chrontel CH7511B?
I haven't had the time to fully troubleshoot, will do as soon as possible, but... :
(1). "echo XXX > /sys/class/backlight/acpi_video0" NOT WORKING. Why is it acpi_video0 & not intel_backlight...?
(2). kernel log messages say something about "drm link training failed...", no idea what this means...
(3). BIOS has option for SMbus & PWM something, will check as soon as possible...
(4). Play around with kernel parameters? Will try as soon as possible...

If anyone has the same display hardware, would be glad if they could share some info...

Thanks.

[Phoenix]

acpi_video is probably the default interface, but displays DO change.
Have you tried the brightnessctl package? It will provide a more simplified interface (and work with many). Although you may need to sort through output if there are more than one thing controllable by Linux.

[williams2]

Typing or copy/paste in a terminal
tail /var/log/Xorg.0.log
should tell you what video driver Puppy is actually using.

It may be using, for example, the vesa driver, not the intel driver, which might not support adjusting brightness.

[bigpuppyfan]

I suggest looking at http://forum.puppylinux.com/viewtopic.p ... 1&start=10

For instance, try:

Code: Select all

root# brightness-set down

And then setting shortcut keys in JWM

[TerryH]

Try this:
echo XXX > /sys/class/backlight/intel_backlight/brightness

The maximum value XXX can be, should be stored in /sys/class/backlight/intel_backligt/max_brightness. This value is probably 937. XXX should be between 001 and up to the max_brightness value. Don´t set it to 0, this will turn the backlight off and you may not be ale to turn it back on.

[Phoenix]

In the case you happen to accidentally 'zero' your display and you know what you're currently running.
If in graphic modes (desktop) press Win (Superkey) + R and type in the relevant commands above to restore it.
If in console mode just type the command as normal. (and press enter)

Although I think it would be significantly easier to restore brightness via 'brightnessctl' instead of having to try and not typo without being able to see the echo command to send it to the correct 'control knob'.

[cj147]

Case closed.

Redshift program works.

Thanks to all informative replies.