media: cadence: cdns-csi2rx: Support multiple pixels per clock cycle

media: cadence: cdns-csi2rx: Support multiple pixels per clock cycle

The output pixel interface is a parallel bus (32 bits), which
supports sending multiple pixels (1, 2 or 4) per clock cycle for
smaller pixel widths like RAW8-RAW16.

Dual-pixel and Quad-pixel modes can be a requirement if the export rate
of the Cadence IP in Single-pixel mode maxes out before the maximum
supported DPHY-RX frequency, which is the case with TI's integration of
this IP [1].

So, we export a function that lets the downstream hardware block request
a higher pixel-per-clock on a particular output pad.

We check if we can support the requested pixels per clock given the
known maximum for the currently configured format. If not, we set it
to the highest feasible value and return this value to the caller.

[1] Section 12.6.1.4.8.14 CSI_RX_IF Programming Restrictions of AM62 TRM

Link: https://www.ti.com/lit/pdf/spruj16
Tested-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com> (on SK-AM68)
Signed-off-by: Jai Luthra <jai.luthra@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>