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V4L/DVB (9315): s5h1411: Skip reconfiguring demod modulation if already at the desired modulation

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If we are already at the desired modulation, there is no need to reconfigure
the demod (at a tuning time cost)

Note that this change revealed that although the datasheet says the demod
starts out in VSB-8 mode, the first tuning was failing consistently unless
we went through the work of setting the registers.  So add a field to denote
this case so we always do the enable_frontend call, even if the first tuning
request is for VSB-8.

Signed-off-by: Devin Heitmueller <devin.heitmueller@gmail.com>
Reviewed-by: Michael Krufky <mkrufky@linuxtv.org>
Acked-by: Steven Toth <stoth@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Devin Heitmueller 2008-10-20 10:19:07 -03:00 committed by Mauro Carvalho Chehab
parent f0d041e50b
commit 50eac6bc46
1 changed files with 13 additions and 0 deletions
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13
drivers/media/dvb/frontends/s5h1411.c
View file

@ -38,6 +38,7 @@ struct s5h1411_state {
struct dvb_frontend frontend;
fe_modulation_t current_modulation;
unsigned int first_tune:1;
u32 current_frequency;
int if_freq;
@ -489,6 +490,12 @@ static int s5h1411_enable_modulation(struct dvb_frontend *fe,
dprintk("%s(0x%08x)\n", __func__, m);
if ((state->first_tune == 0) && (m == state->current_modulation)) {
dprintk("%s() Already at desired modulation. Skipping...\n",
__func__);
return 0;
}
switch (m) {
case VSB_8:
dprintk("%s() VSB_8\n", __func__);
@ -513,6 +520,7 @@ static int s5h1411_enable_modulation(struct dvb_frontend *fe,
}
state->current_modulation = m;
state->first_tune = 0;
s5h1411_softreset(fe);
return 0;
@ -622,6 +630,11 @@ static int s5h1411_init(struct dvb_frontend *fe)
/* The datasheet says that after initialisation, VSB is default */
state->current_modulation = VSB_8;
/* Although the datasheet says it's in VSB, empirical evidence
shows problems getting lock on the first tuning request. Make
sure we call enable_modulation the first time around */
state->first_tune = 1;
if (state->config->output_mode == S5H1411_SERIAL_OUTPUT)
/* Serial */
s5h1411_set_serialmode(fe, 1);