topic Re: how to set brightness on a hdmi display in i.MX Processors

how to set brightness on a hdmi display

edward_fu — Wed, 12 May 2021 06:25:36 GMT

Hello,

There is a case of setting brightness on a hdmi display with imx8mq board.

The hdmi display can support adjusting brightness by DDC/CI protocol, which already implemented in windows application.

So how can I do in imx8mq to set brightness by DDC(HDMI_DDC_SDA, HDMI_DDC_SCL).

Thanks very much.

Re: how to set brightness on a hdmi display

Zhiming_Liu — Thu, 13 May 2021 02:06:52 GMT

Please see this https://blog.tcharles.fr/ddc-ci-screen-control-on-linux/

Zhiming

Re: how to set brightness on a hdmi display

edward_fu — Thu, 13 May 2021 02:54:51 GMT

Hi Zhiming,

Thanks for your quick reply.

The solution is general , but is suitable for imx8mq? Because the ddcutil tool you mentioned need i2c-dev module to be loaded. As we know imx8mq DDC uses HDMI_DDC_SDA, HDMI_DDC_SCL not a common i2c.

Thanks again.

Br,

Edward

Re: how to set brightness on a hdmi display

Zhiming_Liu — Thu, 13 May 2021 05:12:11 GMT

I am finding perfect solution to send ddc message and will update later.

The ddcutil can used in i.mx8mq,i am trying to use i2ctools

Zhiming

Re: how to set brightness on a hdmi display

Zhiming_Liu — Thu, 13 May 2021 08:05:47 GMT

Add this folder into /imx-yocto-bsp/sources/meta-imx/meta-bsp/recipes-support/

And bitbake ddcutil

Re: how to set brightness on a hdmi display

edward_fu — Fri, 14 May 2021 00:33:25 GMT

Thanks for your support. One question, the solution you suggested is still using ddcutil, just compling with yocto. Is it the same with apt-get install ddcutil?

Another question, the .bb fiel you provided indicated that dduutil tool depends on x11(xserver). But as I know imx8mq only supports wayland.

Edward

Re: how to set brightness on a hdmi display

tomsong — Mon, 20 Mar 2023 14:51:01 GMT

Hi,

I tried the attached recipe for ddcutil and it can detect the display however I got a "DDC communication failed" error:

root@imx8mp-var-dart:~# ddcutil detect
Invalid display
I2C bus: /dev/i2c-6
EDID synopsis:
Mfg id: MST
Model: MStar Demo
Product code: 48
Serial number:
Binary serial number: 1 (0x00000001)
Manufacture year: 2010, Week: 10
DDC communication failed

Any suggestions of how to fix it?

Thanks a lot!

Regards,

Tom

Re: how to set brightness on a hdmi display

belpai — Mon, 01 May 2023 09:45:56 GMT

Have you found a way to do that correctly with the imx8mq? @edward_fu @tomsong