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[media] DVB: stb0899: speed up getting BER values

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stb0899_read_ber() takes 500ms (half a second!) to deliver the current
BER value. Apparently it takes 5 subsequent readings, with a 100ms pause
between them (and even before the first one). This is a real performance
brake if an application freqeuently reads the BER of several devices.
The attached patch reduces this to a single reading, with no more pausing.
I didn't observe any negative side effects of this change.

Signed-off-by: Klaus Schmidinger <Klaus.Schmidinger@tvdr.de>
Cc: Manu Abraham <abraham.manu@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Klaus Schmidinger 2012-06-02 11:04:17 -03:00 committed by Mauro Carvalho Chehab
parent 4a62817095
commit fdaaee6c4a
1 changed files with 6 additions and 16 deletions
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22
drivers/media/dvb/frontends/stb0899_drv.c
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@ -1129,7 +1129,6 @@ static int stb0899_read_ber(struct dvb_frontend *fe, u32 *ber)
struct stb0899_internal *internal = &state->internal;
u8 lsb, msb;
u32 i;
*ber = 0;
@ -1137,14 +1136,9 @@ static int stb0899_read_ber(struct dvb_frontend *fe, u32 *ber)
case SYS_DVBS:
case SYS_DSS:
if (internal->lock) {
/* average 5 BER values */
for (i = 0; i < 5; i++) {
msleep(100);
lsb = stb0899_read_reg(state, STB0899_ECNT1L);
msb = stb0899_read_reg(state, STB0899_ECNT1M);
*ber += MAKEWORD16(msb, lsb);
}
*ber /= 5;
lsb = stb0899_read_reg(state, STB0899_ECNT1L);
msb = stb0899_read_reg(state, STB0899_ECNT1M);
*ber = MAKEWORD16(msb, lsb);
/* Viterbi Check */
if (STB0899_GETFIELD(VSTATUS_PRFVIT, internal->v_status)) {
/* Error Rate */
@ -1157,13 +1151,9 @@ static int stb0899_read_ber(struct dvb_frontend *fe, u32 *ber)
break;
case SYS_DVBS2:
if (internal->lock) {
/* Average 5 PER values */
for (i = 0; i < 5; i++) {
msleep(100);
lsb = stb0899_read_reg(state, STB0899_ECNT1L);
msb = stb0899_read_reg(state, STB0899_ECNT1M);
*ber += MAKEWORD16(msb, lsb);
}
lsb = stb0899_read_reg(state, STB0899_ECNT1L);
msb = stb0899_read_reg(state, STB0899_ECNT1M);
*ber = MAKEWORD16(msb, lsb);
/* ber = ber * 10 ^ 7 */
*ber *= 10000000;
*ber /= (-1 + (1 << (4 + 2 * STB0899_GETFIELD(NOE, internal->err_ctrl))));