[PATCH v3 00/24] i.MX Media Driver

[Russell King - ARM Linux]

On Tue, Jan 31, 2017 at 11:09:24AM +0100, Philipp Zabel wrote:
> On Mon, 2017-01-30 at 13:06 +0000, Russell King - ARM Linux wrote:
> > To help illustrate my point, consider the difference between
> > MEDIA_BUS_FMT_RGB565_1X16 and MEDIA_BUS_FMT_RGB565_2X8_BE or
> > MEDIA_BUS_FMT_RGB565_2X8_LE.  RGB565_1X16 means 1 pixel over an effective
> > 16-bit wide bus (if it's not 16-bit, then it has to be broken up into
> > separate "samples".)  RGB565_2X8 means 1 pixel as two 8-bit samples.
> > 
> > So, the 10-bit bayer is 1 pixel as 1.25 bytes.  Or is it, over a serial
> > bus.  Using the RGB565 case, 10-bit bayer over a 4 lane CSI bus becomes
> > interesting:
> > 
> > 	first byte	2nd	3rd
> > lane 1	P0 9:2		S0	P7 9:2
> > lane 2	P1 9:2		P4 9:2	S1
> > lane 3	P2 9:2		P5 9:2	P8 9:2
> > lane 4	P3 9:2		P6 9:2	P9 9:2
> > 
> > S0 = P0/P1/P2/P3 least significant two bits
> > S1 = P4/P5/P6/P7 least significant two bits
> > 
> > or 2 lane CSI:
> > 	first byte	2nd	3rd	4th	5th
> > lane 1	P0 9:2		P2	S0	P5	P7
> > lane 2	P1 9:2		P3	P4	P6	S1
> > 
> > or 1 lane CSI:
> > lane 1	P0 P1 P2 P3 S0 P4 P5 P6 P7 S1 P8 P9 ...
> 
> These do look like three different media bus formats to me.

This isn't limited to the serial side - the parallel bus side between
the CSI2 interface and CSI2IPU wrapper, and the CSI2IPU wrapper and
the CS0/1 interfaces is much the same with 10-bit bayer.

Think of the CSI2 <-> CSI2IPU bit as the 4-lane case, lane 0 ending
up on the least significant 8 bits of the 32-bit bus, lane 3 on the
top 8-bits.

Post CSI2IPU, it talks about a 16-bit bus in the diagrams, so that's
kind of the 2-lane case above...

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