Understanding itest.s for supporting 2 LVDS displays

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Understanding itest.s for supporting 2 LVDS displays

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eric_reyna
Contributor II

So I'm adding support for 2 lvds displays in my bootscript. I'm using the i.MX6 SabreLite board running Android OS. The main problem I have is that the i2c address for both the displays are both on the same i2c address. The main difference between the displays is that interface pixel format is RGB 666 and the other RGB24. I know I need to change the interface pixel format in the dtsi file and bootscript but again I need to able to distinguish between the two displays so they correctly 'autodetect' a different setting (right now it only can detect one display with one pixel format setting). My main thoughts were to set up another lvds channel and framebuffer. I'm guessing I would have to create lvds identifier/panel to distinguish? However, I noticed these lvds identifiers are set in itest.s assembler code. Is this where I need to modify/change my code to add support for another panel?

Any guidance it the right direction is greatly appreciated,

Thank you.

P.S. If there is a pdf document that explains the imx6 device tree?

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igorpadykov
NXP TechSupport
NXP TechSupport

I am afraid different displays with the same i2c address

are not supported in drivers.

Best regards

igor

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Eric

one can look at BD configurations for various lcds as

https://boundarydevices.com/configuring-i-mx6-machines-different-screens-nitrogen6x-sabre-lite/

Device tree docs:

https://events.linuxfoundation.org/sites/events/files/slides/petazzoni-device-tree-dummies.pdf

Device Tree - eLinux.org

Best regards

igor

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eric_reyna
Contributor II

Thanks for the reply and the links! Very helpful.

I've seen BD's new configuration for autodetecting displays by probing for valid I2C addresses using a "build up bootargs process to one that prunes the device tree using the fdt rm command in U-Boot" and setting the proper environment parameters to the bootscript and dtsi file to setup the displays with the proper formatting while pruning (rm) the unused nodes. Now I am just wondering if there is any support in the ipuv driver that allows for different display settings that are using the same i2c address.

Wondering if this is possible?

Your feedback is greatly appreciated.

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igorpadykov
NXP TechSupport
NXP TechSupport

I am afraid different displays with the same i2c address

are not supported in drivers.

Best regards

igor