The IMX8's HDMI interface forces the output to a resolution of 4032x756

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The IMX8's HDMI interface forces the output to a resolution of 4032x756

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ximenbingmeng
Contributor III

I have an 4032x756 lcd I am looking to configure for the imx8m to run it.I am running u-boot 2019.04 and Linux kernel L4.19.35.

My question is how do you generate the required clock speed for a 4032x756&57Hz hdmi LCD?

Here are the screen parameters I use.

I have made the following changes at this time.

I refered to this Driving a 1080x1920 portrait HDMI screen solution.

  1. add below drm mode in drivers/gpu/drm/imx/hdp/imx-hdp.c

{ DRM_MODE("4032x756", DRM_MODE_TYPE_DRIVER, 148500, 4032, 4110,
4132, 4194, 0, 756, 762, 768, 774, 0,
DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
.vrefresh = 50, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, },

2.I refered to thisCustom Resolution 800x480 - NXP Communitysolution.I find the HDMI-pixel clock calculation,but I do not know how to  use it.How to fill in each parameter.

The challenge I am having is what I need to add the spreadsheet for the input variables:

  • Reference Clock Freq
  • Expected Pixel clock
  • Generated clock tolerance
  • pll input divider
  • pll feedback divider
  • pixel clock divider
  • character clock divider

Based on the above modeline should I be able to dervice these values or I need more information?

Any guidance is appreciated.

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ximenbingmeng
Contributor III

HI

Is there any technical support, IMX8MM supports more resolutions and clocks? What manual should I refer to? thank

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AldoG
NXP TechSupport
NXP TechSupport

Hello,

The i.MX8M support up to 4Kp60 resolution on the HDMI and 1080p60 on the MIPI-DSI.

For the PLL configuration you may refer to the i.MX8M reference manual chapter 5.1.5.4.4 SSCG and Fractional PLLs

Best regards,
Aldo.

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lebeer
Contributor II

The i.MX8M support up to 4Kp60 resolution on the HDMI and 1080p60 on the MIPI-DSI.

 

如果同时使用两个HDMI+mipi_dsi,分辨率能够达到多少呢?

 

1080p+720p是极限么?

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