ADV7625 used in splitter mode
Specific HDMI source → ADV7625 → HDMI monitor (TXA)
└ → HDMI monitor (TXB)
In the above configuration,
if the image is left in normal display mode for a while,
the monitor image may suddenly disappear.
The disappearance is random: TXA only, TXB only, or both TXA and TXB.
When checking this state, the PLL_LOCK_STATUS for TXA or TXB is '0'.
Once this happens, the ADV7625 will not output video even if you connect an HDMI test signal generator.
(For example, if the loss is only on the TXA side, TXB will output normally.)
To recover, power cycle only the device equipped with the ADV7625
or
assert TXA_RST or TXB_RST in IO map 0xFE.
This issue is not a defect in any of the components listed above, including the ADV7625.
In other words, the same issue occurs even if you replace a specific HDMI source, ADV7625, and HDMI monitor with multiple different units.
As a temporary solution, we intend to add logic to the firmware (ROM) that asserts TXA_RST or TXB_RST when PLL_LOCK_STATUS = '0' to avoid the worst-case scenario of a "loss."
But essentially,
why did we end up in this situation?
I would like to find out, so please answer the following questions.
Q1: What can cause PLL_LOCK_STATUS to become '0'?
Q2: Please tell me how to recover from this other than asserting TXA_RST/TXB_RST.
Best regards,