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iMX6Q AI board support for 1280×800 HDMI Display

Question asked by Rohit Patle on Aug 6, 2016
Latest reply on Jul 27, 2017 by sanjeev sharma

Hello Experts,

 

I am working on display integration for iMX6Q AI, Here we procured HDMI display with 720p(1280×800, 10.1 inch Captive Touch Screen LCD). But it looks like the default support for the iMX6Q BSP supports only 1080p. Kindly help to add support for 720p.

 

Below is my technical analysis of integration:

 

  1. While in probe as per the cmd line display argument,  we retrieve the display parameters in function mxc_hdmi_disp_init (file : mxc_hdmi.c)
    1. The values retrieved are xres:1280, yres:720, pixclock:13468, hsync_len:40, vsync_len:5, sync:3, vmode:32.  Since in cmdline, I am passing the argument 1280x720@60.

With this parameters, I see the display is working fine on FHD TV. But same is not working with the above 720p display panel I have.

 

  1. There is one important thing to note here is, mxc_hdmi_read_edid function always fails. For my FHD display as well as for the above mentioned panel.

 

  1. When hdmi cable is connected from sabre board to the panel or the TV, mxc_hmi_cable_connected event is triggered. Here it calls mxc_hdmi_read_edid function. But since this function always fails it goes to switch case :”HDMI_EDID_FAIL”

 

After which it will go and configure the default display.

I believe the root of the issue is this failure only. On success it will retrieve all the display parameters(hsync, vsync, clock, resolution etc.) from the target and will set accordingly.

But here it is setting some preconfigured parameters hard coded in imx6 kernel code.

 

  1. I have connected  my Linux as well as windows laptop to the above mentioned panel and I see it works without any issue. I am sure in those environment mxc_hdmi_read_edid function will not be failing.

 

  1. While searching on google I come across below link:

 

https://community.nxp.com/thread/379601.

It seems the issue I am facing is the known issue on imx6 platform. Also, fix for the issue is given in the form of patch here.

But the patch is based on some later version of kernel and so I am unable to apply the patch.

The kernel version I am using is 3.14.52. Is there any later updated version than this for imx6 platform. Please let me know.

 

For more info on HDMI panel I am using, please refer below vendor web site:

http://www.waveshare.com/wiki/10.1inch_HDMI_LCD_(B)_(with_case)

 

Please provide me the patch for above mentioned issue.

 

Thank you,

Rohit

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