On 22/07/2022 19:16, Nishanth Menon wrote:
On 17:28-20220720, Rob Herring wrote:
On the bridge side R0->R2, G0->G1, B0->B2 would be tied to ground.
The bridge sees 24bits of data, but the lsb's are always zero.
Unless the bridge ignores the LSBs, that's not the right way to do 16 to
24 bit. The LSBs should be connected to the MSB of the color component
to get full color range.
I unfortunately cannot point specifics without violating NDAs, so
will just give a broad perspective.
Correct, this is not ideal, but in certain scenarios with limited
pins (due to iovoltage groups), we are indeed starting to see this
kind of usage model starting to pop up. Tradeoff is in a limit on
image quality, but that tends to be acceptable in certain lower cost
solutions.
It doesn't require more pins. If the lowest bits are tied to ground the
image is always a bit darker than it should, and you do not get the full
brightness. But if you wire e.g. the red component:
SoC : Bridge
R2 -> R0
R3 -> R1
R4 -> R2
R0 -> R3
R1 -> R4
R2 -> R5
R3 -> R6
R4 -> R7
or
R4 -> R0
R4 -> R1
R4 -> R2
R0 -> R3
R1 -> R4
R2 -> R5
R3 -> R6
R4 -> R7
You'll get the full range.
Tomi
