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How to add a custom mode for HDMI display

Samip_veer
Associate

I would like to add a custom resolution hdmi display (1024x600) to my STM32MP257F-DK  board  is it possible as the dmesg output is as follows 

[  930.525408] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:32:HDMI-A-1]
[  930.590130] stm32-display 48010000.display-controller: [drm:update_display_info.part.0] [CONNECTOR:32:HDMI-A-1] ELD monitor
[  930.590170] stm32-display 48010000.display-controller: [drm:update_display_info.part.0] [CONNECTOR:32:HDMI-A-1] ELD size 20, SAD count 0
[  930.590208] stm32-display 48010000.display-controller: [drm:update_display_info.part.0] [CONNECTOR:32:HDMI-A-1] ELD monitor
[  930.590223] stm32-display 48010000.display-controller: [drm:update_display_info.part.0] [CONNECTOR:32:HDMI-A-1] ELD size 20, SAD count 0
[  930.591397] [drm:drm_mode_debug_printmodeline] Modeline "1024x600": 60 49000 1024 1072 1168 1312 600 603 613 624 0x48 0xa
[  930.591421] [drm:drm_mode_prune_invalid] Not using 1024x600 mode: CLOCK_RANGE
[  930.591433] [drm:drm_mode_debug_printmodeline] Modeline "800x450": 60 27759 800 816 896 992 450 451 454 466 0x0 0x6
[  930.591450] [drm:drm_mode_prune_invalid] Not using 800x450 mode: CLOCK_RANGE

The display shows CLOCK_RANGE, is there any possible way to add a custom resolution if it is not present by default in the edid data.

3 REPLIES 3
Erwan SZYMANSKI
ST Employee

Hello @Samip_veer ,
Please can you take a look at this wiki article: https://wiki.st.com/stm32mpu/wiki/How_to_display_on_HDMI

I think it can highlight some points you are looking for.

Kind regards,
Erwan.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.
Samip_veer
Associate

Dear @Erwan SZYMANSKI 

Thank you for your reply i had aldready studied the article and also checked various community discussion but the problem if CLOCK_RANGE means i need to set the clock frequency so that the pixel clock frequency matches with my device, can you help me with that as i did not find any relevant material in the article.

Hi @Samip_veer ,
Did you already check this answer from Antonio ? https://community.st.com/t5/stm32-mpus-products-and-hardware/what-are-the-criteria-for-modetest-to-accept-a-modeline/td-p/268952

Did you try to activate debug too to get the exact clock value you get VS the one that is expected ?

Kind regards,
Erwan.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.