diff options
Diffstat (limited to 'drivers/media/dvb/frontends/or51211.c')
| -rw-r--r-- | drivers/media/dvb/frontends/or51211.c | 124 |
1 files changed, 50 insertions, 74 deletions
diff --git a/drivers/media/dvb/frontends/or51211.c b/drivers/media/dvb/frontends/or51211.c index 2bf124b..048d7cf 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; } |
