topic i.MX8 MIPI DSI to LVDS display issue in i.MX Processors

i.MX8 MIPI DSI to LVDS display issue

bensonhuang — Tue, 06 Mar 2018 06:17:06 GMT

Hi,

Processor: i.MX8mq

OS: Yocto (Linux L4.9.51 for i.MX 8MQuad Beta) & Android (Android O8.0.0 for i.MX 8MQuad Beta)

We use Ti SN65DSI83 to transform MIPI DSI signal to LVDS display.

When we turn on SN65DSI83 test pattern mode, we can see test pattern shown on the panel.

But when we turn off SN65DSI83 test pattern mode, we will see LVDS panel will repeat showing red, green, blue, black, white, checkerboard, grey.

Will i.MX8 MIPI DSI generate some test pattern by default?

What is the expected behavior on the panel?

Thanks.

PS: Attach the video of the display.

Bio_TICFSL — Wed, 07 Mar 2018 16:59:47 GMT

Hi Benson,

No, you have enable it somewhere, or this is due to RAM problem.

bensonhuang — Thu, 08 Mar 2018 02:38:52 GMT

Hi Bio_TICFSL,

Thanks for your reply.

You said I have enabled it somewhere, but I don't know how to enable the test pattern.

From the i.MX8 reference manual page 2040, I have seen one register (IOMUXC_GPR_GPR29) which has one field DSI_TEST_PATTERN for DSI test control.

Will the initial value of this register cause the behavior?

If so, how to change the value to turn off the test pattern?

Another point you mentioned is due to the RAM problem.

How to judge if this is the root cause? (From debug log or some other way)

Please give me some advice.

Thanks.

xinchuan — Tue, 29 May 2018 04:20:36 GMT

请问楼主问题解决了吗？我现在也在用SN65DSI83，也只是点亮了测试图像？麻烦指导一下.

jrtigerlee — Tue, 04 Sep 2018 23:27:31 GMT

Hi Benson,

I also found this register , but didn't know how to initial test pattern.

Do you have detail to initial the register and let MIPI DSI interface send test pattern ?