Can someone clarify the setting of the PS Scale Factor Register (PXP_PS_SCALE) in the Pixel Pipeline?
The description in the iMX6 RMs is a tad confusing/incomplete.
The manual says that each X/Y scale is "two bit integer and 12 bit fractional representation" (total 14 bits) but shows the scales occupying 15 bits each (plus a single reserved bit to make up one 16 bit half-word). Am I correct to assume they are really 14 bits each (bits 29-16, 13-0) plus two reserved bits?
Next, the manual says "The reciprocal of the scale factor should be loaded into this register", but it is not clear how to make a "reciprocal" out of the above bit fields.
The following up scaling examples are provided:
00.0100_0000_0000 scale up by 4
00.0010_0000_0000 scale up by 2
00.1010_0000_0000 scale up by 8/5
Especially with the last one I don't see where they are getting the register settings.
The 2x and 4x examples might make sense to me, except that I wonder why the most significant nibble is being set. And how, in that case, would you represent a scaling factor of 0x20 for example?