V4L/DVB (7731): tuner-xc2028: fix signal strength calculus

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 10 insertions, 3 deletions

diff --git a/drivers/media/video/tuner-xc2028.c b/drivers/media/video/tuner-xc2028.c
index a32094e545f7..cc3db7d79a0d 100644
--- a/drivers/media/video/tuner-xc2028.c
+++ b/drivers/media/video/tuner-xc2028.c
@@ -844,21 +844,28 @@ static int xc2028_signal(struct dvb_frontend *fe, u16 *strength)
 
         /* Sync Lock Indicator */
         rc = xc2028_get_reg(priv, 0x0002, &frq_lock);
-        if (rc < 0 || frq_lock == 0)
+        if (rc < 0)
                 goto ret;
 
-        /* Frequency is locked. Return signal quality */
+        /* Frequency is locked */
+        if (frq_lock == 1)
+                signal = 32768;
 
         /* Get SNR of the video signal */
         rc = xc2028_get_reg(priv, 0x0040, &signal);
         if (rc < 0)
-                signal = -frq_lock;
+                goto ret;
+
+        /* Use both frq_lock and signal to generate the result */
+        signal = signal || ((signal & 0x07) << 12);
 
 ret:
         mutex_unlock(&priv->lock);
 
         *strength = signal;
 
+        tuner_dbg("signal strength is %d\n", signal);
+
         return rc;
 }