Next, add this to /etc/rc.local; it waits for a monitor to be attached to the HDMI socket, probes it for its preferred mode, sets that preferred mode and finally resets the framebuffer ready for X to takeover:

rc.local

# Wait for the TV-screen to be turned on...
while ! $( tvservice --dumpedid /tmp/edid | fgrep -qv 'Nothing written!' ); do
	bHadToWaitForScreen=true;
	printf "===> Screen is not connected, off or in an unknown mode, waiting for it to become available...\n"
	sleep 10;
done;

printf "===> Screen is on, extracting preferred mode...\n"
_DEPTH=32;
eval $( edidparser /tmp/edid | fgrep 'preferred mode' | tail -1 | sed -Ene 's/^.+(DMT|CEA) \(([0-9]+)\) ([0-9]+)x([0-9]+)[pi]? @.+/_GROUP=\1;_MODE=\2;_XRES=\3;_YRES=\4;/p' );

printf "===> Resetting screen to preferred mode: %s-%d (%dx%dx%d)...\n" $_GROUP $_MODE $_XRES $_YRES $_DEPTH
tvservice --explicit="$_GROUP $_MODE"
sleep 1;

printf "===> Resetting frame-buffer to %dx%dx%d...\n" $_XRES $_YRES $_DEPTH
fbset --all --geometry $_XRES $_YRES $_XRES $_YRES $_DEPTH -left 0 -right 0 -upper 0 -lower 0;
sleep 1;