GAMMA CHANGE OF DISPLAY

Hi,

I am using jetson tx2. How can I change the gamma of the display connected to it?

I tried the below commands.
xgamma -gamma 0.3
&
xrandr --output HDMI1-0 --gamma 0.8:1:1.

There is no visible change.

Could you firstly try to change this table in kernel source and see if it can work?
default_srgb_regamma_lut -> nvdisp.c

Hi Wayne,

How do I change this table? Is there any particular tool to generate this LUT?

I tried randomly changing few values. There is no change.

Hi blessy.abraham,

Could you toggle the sysfs /sys/class/graphics/fb0/device/cmu_enable?

Hi Wayne,

I tried toggling the sysfs /sys/class/graphics/fb0/device/cmu_enable. Still no change.

You should at least see the color of monitor becomes darker after set cmu_enable to 0, right?

There was no change, the display just blinked in every toggle of the cmu_enable.

We are using a custom display and we changed the edid mentioned in edid.c to another one as the already existing one was not working with our display. Would that be the cause?

Toggling CMU should be able to see some differences. Or maybe it is monitor-dependent.
Could you change other monitor and check?

As for the X driver functionality, our internal team has started debug.

Hi Wayne,

Sorry for the delay. We could see the difference when toggling cmu_enable.
What can I do to configure the RGB / Gamma at the display side?

The gamma value should be defined by the display EDID. I need to confirm with internal team if we could have better solution here.

Thank you Wayne,
Looking forward for the solution.

Hi Wayne,

Any update on this?

Sorry for late reply. This function of xrandr should be working in next release.

Hi Wayne,

Any other possible ways to configure gamma other than xrandr?

I don’t think currently there is any way other than xrandr.

The real problem is the driver of xfree86 does not support it and our internal team is working on it.