V4L/DVB (9315): s5h1411: Skip reconfiguring demod modulation if already at the desired modulation
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>
diff --git a/drivers/media/dvb/frontends/s5h1411.c b/drivers/media/dvb/frontends/s5h1411.c
index 40e0fed..b9ac6d3 100644
--- a/drivers/media/dvb/frontends/s5h1411.c
+++ b/drivers/media/dvb/frontends/s5h1411.c
@@ -38,6 +38,7 @@
struct dvb_frontend frontend;
fe_modulation_t current_modulation;
+ unsigned int first_tune:1;
u32 current_frequency;
int if_freq;
@@ -489,6 +490,12 @@
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 @@
}
state->current_modulation = m;
+ state->first_tune = 0;
s5h1411_softreset(fe);
return 0;
@@ -622,6 +630,11 @@
/* 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);