Cut the comments back to the genuinely subtle ones

fb.go

@@ -10,11 +10,10 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-// Drawing lands in a plain memory buffer and is blitted to a scanout buffer the
-// display is not reading, which is then swapped in whole at a vertical blank.
-// Writing into the live scanout buffer instead, as the fbdev interface invites,
-// races the beam: the blit takes a few hundred microseconds, and whatever the
-// display reads during it is part of one frame and part of the next.
+// Drawing lands in memory and is blitted to a buffer the display is not
+// reading, then swapped in whole at a vertical blank. Writing into the live
+// scanout buffer instead, as fbdev invites, races the beam: the blit takes a
+// few hundred microseconds and the display reads half of each frame.
 const (
 	drmIoctlBase = 0x64
 
@@ -239,7 +238,6 @@ func crtcFor(fd int, c drmModeGetConnector, crtcs []uint32) (uint32, error) {
 	return 0, fmt.Errorf("connector %d has no usable crtc", c.connectorID)
 }
 
-// The connector to drive and a crtc that can drive it.
 func findDisplay(fd int) (connID, crtcID uint32, err error) {
 	crtcs, conns, err := cardResources(fd)
 	if err != nil {
@@ -507,9 +505,8 @@ func (fb *framebuffer) blend(x, y int, c rgb, cov uint8) {
 	fb.back[o+3] = byte(v >> 24)
 }
 
-// Copies into the scanout buffer furthest from being displayed and asks for it
-// at the next blank. The copy cannot tear because nothing is displaying that
-// buffer, and the swap cannot tear because the hardware does it between frames.
+// The copy cannot tear because nothing is displaying that buffer, and the swap
+// cannot tear because the hardware does it between frames.
 func (fb *framebuffer) flush() error {
 	next := (fb.front + 1) % scanoutBuffers
 	copy(fb.bufs[next].mem, fb.back)