driver		maintainer	status
af9013.c	anttip		0.1 dB		
at76c651.c      		(old code to be removed? [stoth])
au8522.c        stoth		0.1 dB
bcm3510.c       pboettch	unknown (vals > 1000)
cinergyT2.c			dB * 256
cx22700.c       		unknown
cx22702.c       		unknown
cx24110.c       		ESN0
cx24116.c       		percent scaled to 0-0xffff, support for ESN0
cx24123.c       		Inverted ESN0
dib3000mb.c     pboettch	unknown
dib3000mc.c     pboettch	always zero (0.1dB possible [pboettch])
dib7000m.c      pboettch	always zero (0.1dB possible [pboettch])
dib7000p.c      pboettch	always zero (0.1dB possible [pboettch])
drx397xD.c      		always zero
dvb_dummy_fe.c  		always zero
l64781.c        		unknown
lgdt330x.c      tpiepho		dB * 256
lgdt3304.c	mrec		always zero
lgdt3305.c      mkrufky		0.1 dB
lgs8gl5.c       		unknown
mt312.c         		agc-feedback 0-0x3FFF
mt352.c         		unknown (0.1dB possible in hardware)
nxt200x.c       mkrufky		dB
nxt6000.c       		unknown
or51132.c       tpiepho		dB * 256
or51211.c       tpiepho		dB * 256
s5h1409.c	stoth  		0.1 dB
s5h1411.c       stoth		0.1 dB
s5h1420.c       		unsupported
si21xx.c        		unknown (scaled to 0-0xffff)
sp8870.c        		unsupported
sp887x.c        		unknown
stv0288.c       		unknown
stv0297.c       		unknown
stv0299.c       		unknown
tda10021.c      		unknown
tda10023.c      		unknown
tda10048.c      		0.1 dB
tda1004x.c      		unknown
tda10086.c      		unknown
tda8083.c       		unknown
tda80xx.c       		unknown
ves1820.c       		unknown
ves1x93.c       		unknown
zl10353.c       		unknown (0.1dB possible in hardware)

Notes:
In cases where the read_snr() call back is not implemented, the return value
provided by dvb_frontend.c is -EOPNOTSUPP, even though the API documentation
expects ENOSYS to be returned.