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V4L/DVB (9270): cx24116: optimise emulated auto-pilot 

Christophe divulged the following:
"Since 8PSK (and higher mod) signals are very likely to have pilot symbols,
pilot_auto should start with pilot_on for 8PSK.
And since QPSK signals are unlikely to have pilot, pilot_auto should start
with pilot_off for QPSK.

Without the patch:
QPSK tuning delay: ~100ms
8PSK tuning delay: ~900ms
with patch:
QPSK tuning delay: ~100ms
8PSK tuning delay: ~100ms
"

This patch does as Cristophe asks. In emulated auto-pilot we
choose pilot-on for tuning PSK_8 and pilot-off for
tuning QPSK.

Signed-off-by: Darron Broad <darron@kewl.org>
Signed-off-by: Steven Toth <stoth@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Christophe Thommeret 2008-10-15 20:01:32 -03:00 committed by Mauro Carvalho Chehab
parent 430189da04
commit 745632147d
1 changed files with 4 additions and 1 deletions
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5
drivers/media/dvb/frontends/cx24116.c
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@ -1248,7 +1248,10 @@ static int cx24116_set_frontend(struct dvb_frontend *fe,
switch (c->pilot) {
case PILOT_AUTO: /* Not supported but emulated */
retune = 2; /* Fall-through */
state->dnxt.pilot_val = (c->modulation == QPSK)
? CX24116_PILOT_OFF : CX24116_PILOT_ON;
retune = 2;
break;
case PILOT_OFF:
state->dnxt.pilot_val = CX24116_PILOT_OFF;
break;