MX6Q HDMI failed to support SXGA(1280x1024@60Hz)

[RobbieJiang]

Hi,

My MX6Q board is basically based on SABRELITE platform.

The HDMI port works well with "1920x1080@60HZ",

with the following kernel cmd line:

setenv hdmiargs  'video=mxcfb0:dev=hdmi,1920x1080@60,if=RGB24,bpp=24'

setenv bootargs_nfs_video 'setenv bootargs ${console} root=/dev/nfs ip=${ipaddr} nfsroot=${nfs_svr}:${nfs_dir},v3,tcp ${hdmiargs}'

setenv bootcmd_video 'run bootargs_nfs_video; tftpboot ${loadaddr} ${kernel}; bootm'

However, if I change the hdmiargs to 1280x1024:

setenv hdmiargs  'video=mxcfb0:dev=hdmi,1280x1024@60,if=RGB24,bpp=24'

nothing is output on the HDMI display with the command "dd if=/dev/urandom of=/dev/fb0".

And according to section "33.4.3 Supported Video Mode" in MX6Q RM,

this sxga mode ( 1280x1024@60Hz) is not included in the supported mode.

Does this mean that the sxga mode can not be supported by the HDMI port?

But in driver/video/mxc_hdmi.c, sxga mode(1280x1024@60Hz)  IS added to the supported video mode list.

Any idea?

Jie

[redwanmohamed]

Hi Eric,

Hope I can use above patch for 854x480 resolution as well (non-cea mode which is not described in i.MX6RM as well as mxc_edid.c).

Are there any changes required in Android? (like adding the resolution in display_mode_fb*.conf and etc ???)

Thanks

Redwan

[redwanmohamed]

I had tuned the pixel clock such that am able to see the penquin logo coming clearly now. But once Android boots up display becomes lost. Tried adding that resolution in display_mode_fb configuration file in Android, but doesnt help much.

Could you please help us on this Android part of configuration

Also have seen a BUG_ON in "kernel_imx/drivers/video/mxc/mxc_edid.c" mxc_edid_read function, Is it resolved in the latest kernel. Am using 3.10.53 kernel

[gary_bisson]

Hi Redwan,

We've never tried this resolution but wouldn't be surprised if Android doesn't like it, especially the hardware composer. What does the logcat say? (please copy the output to pastebin, not as a reply directly).

As for the BUG_ON you experience, we've never seen it on regular HDMI displays (1080p TV/Screens). But maybe you should try the latest Lollipop release based on kernel 3.14.52:

https://boundarydevices.com/android-lollipop-5-1-1-ga-release-for-i-mx6-boards/

Regards,

Gary

[EricNelson]

Hi Robbie,

The 1280x1024 resolution is not a "CEA" mode, so it won't have proper clocking of

HDMI audio. You can find the set of fully supported CEA modes here:

    linux-imx6/mxc_edid.c at boundary-imx_3.10.17_1.0.2_ga · boundarydevices/linux-imx6 · GitHub

More details are available in these posts:

    http://boundarydevices.com/hdmi/

    http://boundarydevices.com/hdmi-cea-mode/

If you're using our boot script or something like it, and our kernel, you can set the "allow_noncea"

flag in U-Boot:

    https://github.com/boundarydevices/u-boot-imx6/blob/production/board/boundary/nitrogen6x/6x_bootscri...

U-Boot > setenv allow_noncea 1
U-Boot > saveenv
U-Boot > boot

This will set the 'only_cea' parameter in the driver to 0 and allow the 1280x1024 mode:

    linux-imx6/mxc_hdmi.c at boundary-imx_3.10.17_1.0.2_ga · boundarydevices/linux-imx6 · GitHub

Note that the HDMI audio clocking will be wrong.