1 files changed, 50 insertions, 74 deletions

diff --git a/drivers/media/dvb/frontends/or51211.c b/drivers/media/dvb/frontends/or51211.c
index 2bf124b53689..048d7cfe12d3 100644
--- a/drivers/media/dvb/frontends/or51211.c
+++ b/drivers/media/dvb/frontends/or51211.c
@@ -39,6 +39,7 @@
 #include <linux/slab.h>
 #include <asm/byteorder.h>
 
+#include "dvb_math.h"
 #include "dvb_frontend.h"
 #include "or51211.h"
 
@@ -63,6 +64,7 @@ struct or51211_state {
 
         /* Demodulator private data */
         u8 initialized:1;
+        u32 snr; /* Result of last SNR claculation */
 
         /* Tuner private data */
         u32 current_frequency;
@@ -292,107 +294,81 @@ static int or51211_read_status(struct dvb_frontend* fe, fe_status_t* status)
         return 0;
 }
 
-/* log10-1 table at .5 increments from 1 to 100.5 */
-static unsigned int i100x20log10[] = {
-                0,  352,  602,  795,  954, 1088, 1204, 1306, 1397, 1480,
-         1556, 1625, 1690, 1750, 1806, 1858, 1908, 1955, 2000, 2042,
-         2082, 2121, 2158, 2193, 2227, 2260, 2292, 2322, 2352, 2380,
-         2408, 2434, 2460, 2486, 2510, 2534, 2557, 2580, 2602, 2623,
-         2644, 2664, 2684, 2704, 2723, 2742, 2760, 2778, 2795, 2813,
-         2829, 2846, 2862, 2878, 2894, 2909, 2924, 2939, 2954, 2968,
-         2982, 2996, 3010, 3023, 3037, 3050, 3062, 3075, 3088, 3100,
-         3112, 3124, 3136, 3148, 3159, 3170, 3182, 3193, 3204, 3214,
-         3225, 3236, 3246, 3256, 3266, 3276, 3286, 3296, 3306, 3316,
-         3325, 3334, 3344, 3353, 3362, 3371, 3380, 3389, 3397, 3406,
-         3415, 3423, 3432, 3440, 3448, 3456, 3464, 3472, 3480, 3488,
-         3496, 3504, 3511, 3519, 3526, 3534, 3541, 3549, 3556, 3563,
-         3570, 3577, 3584, 3591, 3598, 3605, 3612, 3619, 3625, 3632,
-         3639, 3645, 3652, 3658, 3665, 3671, 3677, 3683, 3690, 3696,
-         3702, 3708, 3714, 3720, 3726, 3732, 3738, 3744, 3750, 3755,
-         3761, 3767, 3772, 3778, 3784, 3789, 3795, 3800, 3806, 3811,
-         3816, 3822, 3827, 3832, 3838, 3843, 3848, 3853, 3858, 3863,
-         3868, 3874, 3879, 3884, 3888, 3893, 3898, 3903, 3908, 3913,
-         3918, 3922, 3927, 3932, 3936, 3941, 3946, 3950, 3955, 3960,
-         3964, 3969, 3973, 3978, 3982, 3986, 3991, 3995, 4000, 4004,
-};
-
-static unsigned int denom[] = {1,1,100,1000,10000,100000,1000000,10000000,100000000};
+/* Calculate SNR estimation (scaled by 2^24)
 
-static unsigned int i20Log10(unsigned short val)
-{
-        unsigned int rntval = 100;
-        unsigned int tmp = val;
-        unsigned int exp = 1;
+   8-VSB SNR equation from Oren datasheets
 
-        while(tmp > 100) {tmp /= 100; exp++;}
+   For 8-VSB:
+     SNR[dB] = 10 * log10(219037.9454 / MSE^2 )
 
-        val = (2 * val)/denom[exp];
-        if (exp > 1) rntval = 2000*exp;
+   We re-write the snr equation as:
+     SNR * 2^24 = 10*(c - 2*intlog10(MSE))
+   Where for 8-VSB, c = log10(219037.9454) * 2^24 */
 
-        rntval += i100x20log10[val];
-        return rntval;
+static u32 calculate_snr(u32 mse, u32 c)
+{
+        if (mse == 0) /* No signal */
+                return 0;
+
+        mse = 2*intlog10(mse);
+        if (mse > c) {
+                /* Negative SNR, which is possible, but realisticly the
+                demod will lose lock before the signal gets this bad.  The
+                API only allows for unsigned values, so just return 0 */
+                return 0;
+        }
+        return 10*(c - mse);
 }
 
-static int or51211_read_signal_strength(struct dvb_frontend* fe, u16* strength)
+static int or51211_read_snr(struct dvb_frontend* fe, u16* snr)
 {
         struct or51211_state* state = fe->demodulator_priv;
         u8 rec_buf[2];
-        u8 snd_buf[4];
-        u8 snr_equ;
-        u32 signal_strength;
+        u8 snd_buf[3];
 
         /* SNR after Equalizer */
         snd_buf[0] = 0x04;
         snd_buf[1] = 0x00;
         snd_buf[2] = 0x04;
-        snd_buf[3] = 0x00;
 
         if (i2c_writebytes(state,state->config->demod_address,snd_buf,3)) {
-                printk(KERN_WARNING "or51211: read_status write error\n");
+                printk(KERN_WARNING "%s: error writing snr reg\n",
+                       __FUNCTION__);
                 return -1;
         }
-        msleep(3);
         if (i2c_readbytes(state,state->config->demod_address,rec_buf,2)) {
-                printk(KERN_WARNING "or51211: read_status read error\n");
+                printk(KERN_WARNING "%s: read_status read error\n",
+                       __FUNCTION__);
                 return -1;
         }
-        snr_equ = rec_buf[0] & 0xff;
 
-        /* The value reported back from the frontend will be FFFF=100% 0000=0% */
-        signal_strength = (((5334 - i20Log10(snr_equ))/3+5)*65535)/1000;
-        if (signal_strength > 0xffff)
-                *strength = 0xffff;
-        else
-                *strength = signal_strength;
-        dprintk("read_signal_strength %i\n",*strength);
+        state->snr = calculate_snr(rec_buf[0], 89599047);
+        *snr = (state->snr) >> 16;
+
+        dprintk("%s: noise = 0x%02x, snr = %d.%02d dB\n", __FUNCTION__, rec_buf[0],
+                state->snr >> 24, (((state->snr>>8) & 0xffff) * 100) >> 16);
 
         return 0;
 }
 
-static int or51211_read_snr(struct dvb_frontend* fe, u16* snr)
+static int or51211_read_signal_strength(struct dvb_frontend* fe, u16* strength)
 {
-        struct or51211_state* state = fe->demodulator_priv;
-        u8 rec_buf[2];
-        u8 snd_buf[4];
-
-        /* SNR after Equalizer */
-        snd_buf[0] = 0x04;
-        snd_buf[1] = 0x00;
-        snd_buf[2] = 0x04;
-        snd_buf[3] = 0x00;
-
-        if (i2c_writebytes(state,state->config->demod_address,snd_buf,3)) {
-                printk(KERN_WARNING "or51211: read_status write error\n");
-                return -1;
-        }
-        msleep(3);
-        if (i2c_readbytes(state,state->config->demod_address,rec_buf,2)) {
-                printk(KERN_WARNING "or51211: read_status read error\n");
-                return -1;
-        }
-        *snr = rec_buf[0] & 0xff;
-
-        dprintk("read_snr %i\n",*snr);
+        /* 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%   */
+        struct or51211_state* state = (struct or51211_state*)fe->demodulator_priv;
+        u16 snr;
+        int ret;
+
+        ret = fe->ops.read_snr(fe, &snr);
+        if (ret != 0)
+                return ret;
+        /* Rather than use the 8.8 value snr, use state->snr which is 8.24 */
+        /* scale the range 0 - 35*2^24 into 0 - 65535 */
+        if (state->snr >= 8960 * 0x10000)
+                *strength = 0xffff;
+        else
+                *strength = state->snr / 8960;
 
         return 0;
 }