[quote user="Pavel Botev"]Could you please provide more details about the DAC status? I see that when we set value in the DACXE bits, this value is accepted and can be read afterwards.[/quote]
Yes, the values of the DACXE bits seem to be set and read-back just fine.
[quote user="Pavel Botev"]Checking the source document for this DM814x HDVPSS user guide, I see we have 4 bits for the SD VENC DAC, same as DM816x HDVPSS user guide, bits 27,26,25 and 24. I experiment with this register and [27:24] bit field. By default in u-boot, the value is 0x00000000. I can successfully set all for bits to 0x1, I write 0x010000000, 0x03000000, 0x07000000 and 0x0F000000. But when I try with 0x1F000000, I read back 0x0F000000. Which means we have something mapped on the [27:24] bits, same as DM816x HDVPSS.[/quote]
Agreed, the above matches with our experience (i.e. we can write and read-back bits [27:24] but not other reserved bits).
[quote user="Pavel Botev"]When I set 0x0 (disable) in some of the 27:24 bits, the value is accepted, meaning the corresponding DAC is powered down. Why you think the DAC is not powered down? Do I miss something?[/quote]
Regardless of the value of DAC0E, DAC0 is always "on"; an active video signal is present when the DM814x DAC output is probed with a 'scope. The same is true for DAC1E.
Also, if I clear VIEN to '0' in SD_VENC_vmod, both DACs show no active video signal on the 'scope (which is interesting, but doesn't help us mitigate radiated EMI from the unused DAC1)
I haven't dug our DM814x EVM out of storage to verify, but I suspect I'd find the same behavior on that platform as well given that our board's SD video output looks very similar to the EVM.
-Cory