struct

Selects the index of the plane where the output is scaled. An index of 0

indicates that the output of the whole pipe is scaled.

The value of `scaled_plane_index` must not exceed the number of

planes supported by the pipe. On Tiger Lake, each pipe has 7 planes.

The caller must guarantee that the plane / pipe fulfills all the

constraints below:

- The input size of the pipe / plane must be at least 8 scanlines.

- IF (Interlaced fetch) mode must be disabled.

- Keying can only be enabled if the scaling factor is 1.

- The pixel format must not be 8-bit indexed or XR_BIAS.

- Floating point source pixel values must be within the [0.0, 1.0] range.

- For HDR planes (Plane 1 - 3), the `plane_scaling_enabled` field of the

`PLANE_CUS_CTL` register must be enabled.