No Picture with DSI to LVDS bridge SN65DSI83

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No Picture with DSI to LVDS bridge SN65DSI83

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thom
Contributor II

Hay Guys, 

i have the following problem.

I port the driver for the SN65DSI83 to the current Linux Kernel (4.14.98_2.0.0 from NXP). 

The Driver and dts are fine compilted and working (see log). But i dont get a picture on my Display. So i checked the Registers of the SN65DSI83 and all looks fine... 

Did anyone have a idea to fix this problem? 

Source of the Driver: 

https://github.com/varigit/linux-imx/tree/imx_4.14.78_1.0.0_ga_var01/drivers/gpu/drm/bridge/sn65dsi8...

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thom
Contributor II

Hay Guys, 

thx for the Help. I looks like an Issue in 4.14.98 Kernel. 

I compiled the 4.14.78 Kernel and its Working after so Hours of playing. 

Can anyone tell me what is the difference betwen 4.14.78 / 4.14.98 Kernel within DSI Configuration? 

I see with the Scope, the Data on the DSI Lanes are completly different. 

Now i use a 2 Lane Configuration with 422 MHz Clock.

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rda_emcraft
Contributor I

Hello Thomas,

Can you, please, share your working DTS and point to exact SN65DSI83 driver version that works?

Dmitry

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thorben
Contributor II

Hi Thomas,

have you been able to get 4.14.98 kernel running with SN65DSI83?

Thorben

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thom
Contributor II

Hay guys, 

thx for the Informations. So i attach the .dts file. 

I use the imx8mmevk for testing currently. 

with kind of probe is missing there? 

I set the DSI Lanes to the rigth count (4) and the frequency is set to 213.3MHz. I see with the scope some data and the stable Clock. So i think the DSI Init would be fine there. 

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felixradensky
Contributor IV

Hi Tomas,

There's no SN65DSI83 bridge on NXP EVK. Do you have it on some add-on card ?

Felix.

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igorpadykov
NXP TechSupport
NXP TechSupport

in general also one can try to adjust custom specific lcd sctructures

struct cmd_set_entry manufacturer_cmd_set[], struct display_timing rad_default_timing

in linux/drivers/gpu/drm/panel/panel-raydium-rm67191.c

panel-raydium-rm67191.c\panel\drm\gpu\drivers - linux-imx - i.MX Linux kernel 

Best regards
igor

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Thomas

one can check "display-timings" in fsl-imx8mq-evk-dcss-rm67191.dtsi file

linux-imx/fsl-imx8mq-evk-dcss-rm67191.dtsi at imx_4.14.78_1.0.0_ga_var01 · varigit/linux-imx · GitHu... 

DART-MX8M Display - Variscite Wiki 

Best regards
igor

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felixradensky
Contributor IV

Hi Thomas,

Please check the number of DSI lanes in LVDS bridge DTS node. We have intentionally set it to 1 to workaround limitations of MIPI-DSI bridge driver in kernel 4.14.78. These limitations are supposed to be fixed in kernel 4.14.98, so you try using the real number of DSI lines supported by you panel.

If you're using Variscite DART-MX8M-MINI module you can ask for assistance on our Customer Portal 

Felix.

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mueller12
Contributor III

Hi,

depending on your exact setup:

driver stack maybe missing deferred probing

you maybe need to tweak pixel clock to make dsi driver happy

have you tried with lcdif and dcss?

Only few of the things I remember when playing around with DSI-To-X bridges from TI and NXP 4.14.78_1.0.0

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