On CRTCs 0/2, R1>R0 generates 1µs of border at the end of the raster line. On CRTCs 1/3/4, it does not.
=== R1 conflict ===
If R1=0, there is a conflict between 2 expected behaviours of the CRTC:
* activation of HBORDER when HCC=0 as R1=0
* deactivation of HBORDER on the condition HCC=0
In this situation, all CRTCs chose to do a deactivation of HBORDER
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