Regarding guard band output in HDMI/DVI output mode.

[Yoshiharaaa]

In the HDMI certification test, the ID7-33 HDMI/DVI output mode compatibility test result was FAIL.

Questions
・Guard band was not transmitted in all five tests of ID:7-33.
Isn't the guard band itself not being transmitted as a function?
(Contradiction: In the test results for ID:7-33a using the same software, a guard band is transmitted.)
・I initialize before switching to HDMI/DVI mode, but is there any logic to allow/disallow guard band transmission?
・Is VSDB involved in permitting/disallowing guard band transmission?

Please let me know how to solve this problem.

Thank you.
Yoshihara

[joanxie]

which HDMI of processor do you use?

[Yoshiharaaa]

Thank you for reply.

I used a device with IMX8MP and took the certification test for HDMI 1.4b Source device.

I would like to know why the guard band is not output when outputting HDMI and how to control it.

Thank you.

@joanxie 

[joanxie]

did you test on the latest bsp version?

[Yoshiharaaa]

Hello,@joanxie san

Sorry, I will make some corrections as a result of the investigation.
We have confirmed that the reason why Guard Band is not output is that the HDMI/DVI mode switching is not done properly.If the mode switching is done, it will work normally.

When reading EDID, the HDMI/DVI mode cannot be switched properly, and the previous information appears to be reflected.
Even if you reset the HDP, the mode does not change at all, and it will be reflected when the power is turned on again.
application, but HDMI/DVI does not switch properly.
I would like to know the solution.

Test Item	Result
No.	EDID(Expected value)	Pattern1	Pattern2
1	DVI	DVI	HDMI
2	HDMI	DVI	DVI
3	HDMI	DVI	HDMI
4	DVI	DVI	HDMI
5	HDMI	DVI	DVI
Process 1 to 5 in order

＞did you test on the latest bsp version?

　The kernel will be v5.4.24-2.1.0.
　The version of yocto is 3.0.2.

Thank you,

yoshihara

[joanxie]

did you pass 7-1 test? which is related to the  EDID IF

[Yoshiharaaa]

@joanxie -san

Sorry for the delay in my reply.
I passed ID:7-1.

I researched this issue and was able to resolve it the other day.
The reason for not being able to switch HDMI/DVI after obtaining EDID was in the user application.

I successfully passed the HDMI compliance test.

Thank you for your support.

Thank you,

Yoshihara

[joanxie]

glad to hear this and share this useful information here