>Em Sat, 16 Aug 2014 14:12:32 +0800 >"nibble.max" <nibble....@gmail.com> escreveu: > >> The current m88ts2022 driver will miss the following high symbol rate >> transponders on Telstar 18 138.0. >> 12385 H 43200, >> 12690 H 43200, >> 12538 V 41250... >> the code for f_3db_hz will overflow for the high symbol rate. >> for example, symbol rate=41250 KS/s >> symbol_rate * 135UL = 5568750000(1 4BEC 61B0), the value is larger than >> unsigned int on 32bit platform. >> that makes the wrong result. >> Exchanging the div and mul position fixs it. >> >> Signed-off-by: Nibble Max <nibble....@gmail.com> >> --- >> drivers/media/tuners/m88ts2022.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/media/tuners/m88ts2022.c >> b/drivers/media/tuners/m88ts2022.c >> index 40c42de..65c8acc 100644 >> --- a/drivers/media/tuners/m88ts2022.c >> +++ b/drivers/media/tuners/m88ts2022.c >> @@ -314,7 +314,7 @@ static int m88ts2022_set_params(struct dvb_frontend *fe) >> div_min = gdiv28 * 78 / 100; >> div_max = clamp_val(div_max, 0U, 63U); >> >> - f_3db_hz = c->symbol_rate * 135UL / 200UL; >> + f_3db_hz = (c->symbol_rate / 200UL) * 135UL; > >Hmm... wouldn't this make worse for low symbol rates? > The unit of symbol rate for Satellite is KS/s(1000S/s). So it is safe to divide 200 at the first. >IMHO, the better is to use a u64 instead, and do_div64(). > >> f_3db_hz += 2000000U + (frequency_offset_khz * 1000U); >> f_3db_hz = clamp(f_3db_hz, 7000000U, 40000000U); >> > >Regards, >-- > >Cheers, >Mauro
<<attachment: nibble.max(3).vcf>>
