Question, i.MX6Q DVI_mode setting

[Aemj]

Hello team,

I would like to ask about the setting of the DVI_mode bitfield in i.MX6Q HDMI_FC_INVIDCONF register.

Could you show me the exact difference in terms of i.MX6 behavior between setting the DVI_mode bit and clearing the bit?

Thanks,

Miyamoto

[danielleloader]

Hi Miyamoto,

We're currently trying to get our iMX6-based product to output video to DVI screens. So far we've found that HDMI monitors, and monitors with dual HDMI/DVI ports work fine, but DVI-only monitors (especially older models) will only display video if I manually set this bit to 0 (DVI mode). It seems to default to 1 (HDMI mode) at least once the kernel and video driver is running.

The problem I have found is that even with this bit set to 0, DVI-only monitors do not maintain sync very well, and I have yet to find a way of setting it without JTAG.

[Aemj]

Hi team,

Thanks for your information.

I am still not sure what is actually changed by setting or clearing the bit.

My customer will use the port as DVI not HDMI.

Should the customer set the bit to 0(DVI mode)?

Thanks,

Miyamoto

[Yuri]

  Hello,

> Should the customer set the bit to 0(DVI mode)?

Yes.

   Also, when using HDMI->DVI adapter, the following from Artur may be helphul :

   "Finally, I've been able to make the 1280x1024 DVI monitor (LG Flatron 1710) work

with the i.MX6Q SDP board running L3.10.53 BSP through the HDMI output and

passive HDMI->DVI adapter. To do it, I've added the new 'allow_noncea=1'

environment variable in the U-Boot configuration and the following arguments to

the kernel command line: 'video=mxcfb0:dev=hdmi,1280x1024M@60,if=RGB24'. The

setup looked like following for my case of booting from external SD card on the

SD3 (J507 connector on the board) interface.

U-Boot>setenv allow_noncea 1

U-Boot>setenv mmcargs 'setenv bootargs console=${console},${baudrate} ${smp} root=${mmcroot} video=mxcfb0:dev=hdmi,1280x1024M@60,if=RGB24'

U-Boot>saveenv

These settings forcedly fix the HDMI resolution to 1280x1024 and make the DVI monitor work correctly."

Regards,

Yuri.

[Yuri]

Hello,

  According to HDMI specs, all HDMI Sources shall be compatible with DVI compliant
sink devices (i.e. “monitors” or “displays”) through the use of a passive cable converter.

The DVI_mode bit is used to meet  the requirement for DVI Compatibility.  

Have a great day,
Yuri

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