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-rw-r--r--drivers/media/dvb/frontends/s5h1409.c31
1 files changed, 30 insertions, 1 deletions
diff --git a/drivers/media/dvb/frontends/s5h1409.c b/drivers/media/dvb/frontends/s5h1409.c
index 0e2f61a8978..0d6d5e3e2c3 100644
--- a/drivers/media/dvb/frontends/s5h1409.c
+++ b/drivers/media/dvb/frontends/s5h1409.c
@@ -879,7 +879,36 @@ static int s5h1409_read_snr(struct dvb_frontend *fe, u16 *snr)
static int s5h1409_read_signal_strength(struct dvb_frontend *fe,
u16 *signal_strength)
{
- return s5h1409_read_snr(fe, signal_strength);
+ /* borrowed from lgdt330x.c
+ *
+ * Calculate strength from SNR up to 35dB
+ * Even though the SNR can go higher than 35dB,
+ * there is some comfort factor in having a range of
+ * strong signals that can show at 100%
+ */
+ u16 snr;
+ u32 tmp;
+ int ret = s5h1409_read_snr(fe, &snr);
+
+ *signal_strength = 0;
+
+ if (0 == ret) {
+ /* The following calculation method was chosen
+ * purely for the sake of code re-use from the
+ * other demod drivers that use this method */
+
+ /* Convert from SNR in dB * 10 to 8.24 fixed-point */
+ tmp = (snr * ((1 << 24) / 10));
+
+ /* Convert from 8.24 fixed-point to
+ * scale the range 0 - 35*2^24 into 0 - 65535*/
+ if (tmp >= 8960 * 0x10000)
+ *signal_strength = 0xffff;
+ else
+ *signal_strength = tmp / 8960;
+ }
+
+ return ret;
}
static int s5h1409_read_ucblocks(struct dvb_frontend *fe, u32 *ucblocks)