imx6 - HDMI and DVI issue

[Ansari]

Hi,

We are using imx6Q sabresd platform for our development with Linux 3.10.17_1.0.0-GA BSP.
 
We have enabled the HDMI frame buffer (fb2) by below command

$echo 0 > /sys/class/graphics/fb2/blank

We have connected the HDMI monitor and it is working fine.

After that we have removed the HDMI monitor and connected the DVI monitor.  At this case, the fb2 mode is changed to 640x480p as expected.

The issue we are facing is,  If I connect the HDMI monitor again after removable of DVI monitor, the board is hanging.

The issue is raising at the time of changing the DVI monitor  to HDMI monitor only.

In addition, we are not facing this issue in L3.0.35_4.** release based kernel.

Thank You,

Regards,

Ansari

[controlhorus]

Hello Abdul

We are having problems trying to use our DVI monitor connected to the HDMI ouput. We want to work with 1280x1024 resolution but it goes to 640x480 always.

Abdul Raseeth Ansari escribió:

....  At this case, the fb2 mode is changed to 640x480p as expected.

I have looking for a solution and I found more questions than answers so I will add some more ... questions, sorry

Why was that expected?

When I start without the DVI monitor connected I can see a lot of modes (cat /sys/class/graphics/fb0/modes), V:1280x1024p-60 between them

When I start with the DVI monitor connected I can see only two same modes: V:640x480p-60

Is there a way to force the HDMI-DVI resolution through kernel boot parameters?

I can see that /sys/class/graphics/fb0 can be accesed in several ways. Is there any way to change resolution at runtime with them?

Thanks and best regards,

Jose

[controlhorus]

Hello

Some things:

- not all HDMI-DVI adapters work in the same way

- not all DVI monitors work in the same way

- the mxc_hdmi.c driver have misterious, for me, ways with the possible combinations ont he two previous points

I want to work at 1280x1024 with my board and DVI monitors.

3.0.35 workaround)

  mxc_hdmi.c

    Replace:

               edid_status = mxc_hdmi_read_edid(hdmi);

     with

               edid_status =HDMI_EDID_NO_MODES;

     It will force the driver to build mode list with  sxga_mode included

     Compile and test with the sxga_mode default values

     Adjust that values to the monitor

3.10.17 workaround)

  mxc_hdmi.c

   Copy the sxga_mode from 3.0.35 and its references from 3.0.35 mxc_hdmi.c to 3.10.17 mxc_hdmi.c

  Do the 3.0.35 workaround

Thanks and good luck

[jamesbone]

Hello Abdul,

So you are usign a HDMI-DVI  Cable converter to attach the Monitor? in your testing? or how is that you change from one to another?

what are the bootargs? that you are using? .  YOu never do the echo command again once you change the HDMI to DVI and back to HDMI?

[Ansari]

Hi

Thanks for your input.

>> So you are usign a HDMI-DVI  Cable converter to attach the Monitor?

Yes.  We are using HDMI - DVI cable to attach the (DVI) monitor.

>> in your testing? or how is that you change from one to another?

We just removed the HDMI-DVI cable  (of DVI  moniter) from the board and then HDMI cable (of HDMI display) is connected.

>> what are the bootargs? that you are using? .

We didn't change the bootargs from the default one.  Since we have used the Linux3.1017GA release binaries only

>> YOu never do the echo command again once you change the HDMI to DVI and back to HDMI?

We have executed the below command at very first time only after booting the linux kernel.

$echo 0 > /sys/class/graphics/fb2/blank

Thank You,

Regards,

Ansari

[jamesbone]

Hello Abdul,

Can you please, make the same step-by-step using this kernel:

http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/log/?h=imx_3.10.31_1.1.0_beta

and see if you can reproduce the same?. We are trying to define if it is only a problem on the previous BSP.

Have a great day,
Jaime

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[jamesbone]

We are discussing internally your issue, I will back to you as soon as we have an update.