The attached patch makes changes to the or51132 frontend to match the SNR and
signal strength methods in the lgdt330x frontend. It removes an embedded log
function in favor of using the functions in dvb_math.
Rusty
# HG changeset patch
# User rscott@xxxxxxxxxxxxxxxxxxxxx
# Node ID c39ba3f17ee9ac7aa51bb586da373782413ee0dc
# Parent f48b072c5676460e3fcf01d1b0369e88629c1e46
or51132: Changed SNR and signal strength reporting
From: Rusty Scott <rustys@xxxxxxxx>
Removes embedded log functions and makes use of the DVB math functions
to provide SNR in dB. The changes are modeled after recent changes made
to the LGDT330x frontend in lgdt330x.c
Signed-off-by: Rusty Scott <rustys@xxxxxxxx>
diff -r f48b072c5676 -r c39ba3f17ee9 linux/drivers/media/dvb/frontends/or51132.c
--- a/linux/drivers/media/dvb/frontends/or51132.c Thu Nov 09 00:06:26 2006 -0200
+++ b/linux/drivers/media/dvb/frontends/or51132.c Fri Nov 10 00:02:58 2006 -0700
@@ -40,6 +40,7 @@
#include <linux/slab.h>
#include <asm/byteorder.h>
+#include "dvb_math.h"
#include "dvb_frontend.h"
#include "dvb-pll.h"
#include "or51132.h"
@@ -62,6 +63,7 @@ struct or51132_state
/* Demodulator private data */
fe_modulation_t current_modulation;
+ u32 snr; /* Result of last SNR calculation */
/* Tuner private data */
u32 current_frequency;
@@ -465,124 +467,130 @@ static int or51132_read_status(struct dv
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};
-
-static unsigned int i20Log10(unsigned short val)
-{
- unsigned int rntval = 100;
- unsigned int tmp = val;
- unsigned int exp = 1;
-
- while(tmp > 100) {tmp /= 100; exp++;}
-
- val = (2 * val)/denom[exp];
- if (exp > 1) rntval = 2000*exp;
-
- rntval += i100x20log10[val];
- return rntval;
-}
-
-static int or51132_read_signal_strength(struct dvb_frontend* fe, u16* strength)
+/* Calculate SNR estimation (scaled by 2^24)
+
+ 8-VSB SNR and QAM equations from Oren datasheets
+
+ For 8-VSB:
+ SNR[dB] = 10 * log10(897152044.8282 / MSE^2 ) - K
+
+ Where K = 0 if NTSC rejection filter is OFF; and
+ K = 3 if NTSC rejection filter is ON
+
+ For QAM64:
+ SNR[dB] = 10 * log10(897152044.8282 / MSE^2 )
+
+ For QAM256:
+ SNR[dB] = 10 * log10(907832426.314266 / MSE^2 )
+
+ We re-write the snr equation as:
+ SNR * 2^24 = 10*(c - 2*intlog10(MSE))
+ Where for QAM256, c = log10(907832426.314266) * 2^24
+ and for 8-VSB and QAM64, c = log10(897152044.8282) * 2^24 */
+
+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 or51132_read_snr(struct dvb_frontend* fe, u16* snr)
{
struct or51132_state* state = fe->demodulator_priv;
unsigned char rec_buf[2];
unsigned char snd_buf[2];
- u8 rcvr_stat;
- u16 snr_equ;
- u32 signal_strength;
- int usK;
-
+ u32 noise;
+ u32 c;
+ u32 usK;
+
+ /* Register is same for VSB or QAM firmware */
snd_buf[0]=0x04;
snd_buf[1]=0x02; /* SNR after Equalizer */
msleep(30); /* 30ms */
if (i2c_writebytes(state,state->config->demod_address,snd_buf,2)) {
- printk(KERN_WARNING "or51132: read_status write error\n");
+ printk(KERN_WARNING "%s: error writing snr reg\n",
+ __FUNCTION__);
return -1;
}
msleep(30); /* 30ms */
if (i2c_readbytes(state,state->config->demod_address,rec_buf,2)) {
- printk(KERN_WARNING "or51132: read_status read error\n");
- return -1;
- }
- snr_equ = rec_buf[0] | (rec_buf[1] << 8);
- dprintk("read_signal_strength snr_equ %x %x (%i)\n",rec_buf[0],rec_buf[1],snr_equ);
-
- /* Receiver Status */
+ printk(KERN_WARNING "%s: error reading snr reg\n",
+ __FUNCTION__);
+ return -1;
+ }
+ noise = rec_buf[0] | (rec_buf[1] << 8);
+ dprintk("read_snr noise %x %x (%i)\n",rec_buf[0],rec_buf[1],noise);
+
+ /* Read status, contains modulation type for QAM_AUTO and
+ NTSC filter for VSB */
snd_buf[0]=0x04;
- snd_buf[1]=0x00;
- msleep(30); /* 30ms */
+ snd_buf[1]=0x00; /* Status register */
if (i2c_writebytes(state,state->config->demod_address,snd_buf,2)) {
- printk(KERN_WARNING "or51132: read_signal_strength read_status write error\n");
- return -1;
- }
- msleep(30); /* 30ms */
+ printk(KERN_WARNING "%s: error writing status.\n",
+ __FUNCTION__);
+ return -1;
+ }
if (i2c_readbytes(state,state->config->demod_address,rec_buf,2)) {
- printk(KERN_WARNING "or51132: read_signal_strength read_status read error\n");
- return -1;
- }
- dprintk("read_signal_strength read_status %x %x\n",rec_buf[0],rec_buf[1]);
- rcvr_stat = rec_buf[1];
- usK = (rcvr_stat & 0x10) ? 3 : 0;
-
- /* The value reported back from the frontend will be FFFF=100% 0000=0% */
- signal_strength = (((8952 - i20Log10(snr_equ) - usK*100)/3+5)*65535)/1000;
- if (signal_strength > 0xffff)
+ printk(KERN_WARNING "%s: error reading status.\n",
+ __FUNCTION__);
+ return -1;
+ }
+ usK = 0;
+ switch (state->current_modulation) {
+ case VSB_8:
+ usK = (rec_buf[1] & 0x10) ? 0x03000000 : 0;
+ /* Fall through to QAM64 case */
+ case QAM_64:
+ c = 150204167;
+ break;
+ case QAM_256:
+ c = 150290396;
+ break;
+ case QAM_AUTO:
+ c = (rec_buf[0] == 0x43) ? 150204167 : 150290396;
+ break;
+ default:
+ printk(KERN_ERR "%s: modulation set to unsupported type\n",
+ __FUNCTION__);
+ return -1;
+ }
+ /* Determine scaling factor */
+ state->snr = calculate_snr(noise, c) - usK;
+ *snr = (state->snr) >> 16;
+
+ dprintk("%s: noise = 0x%08x, snr = %d.%02d dB\n", __FUNCTION__, noise,
+ state->snr >> 24, (((state->snr>>8) & 0xffff) * 100) >> 16);
+
+ return 0;
+}
+
+static int or51132_read_signal_strength(struct dvb_frontend* fe, u16* strength)
+{
+ /* 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 or51132_state* state = (struct or51132_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 = signal_strength;
- dprintk("read_signal_strength %i\n",*strength);
-
- return 0;
-}
-
-static int or51132_read_snr(struct dvb_frontend* fe, u16* snr)
-{
- struct or51132_state* state = fe->demodulator_priv;
- unsigned char rec_buf[2];
- unsigned char snd_buf[2];
- u16 snr_equ;
-
- snd_buf[0]=0x04;
- snd_buf[1]=0x02; /* SNR after Equalizer */
- msleep(30); /* 30ms */
- if (i2c_writebytes(state,state->config->demod_address,snd_buf,2)) {
- printk(KERN_WARNING "or51132: read_snr write error\n");
- return -1;
- }
- msleep(30); /* 30ms */
- if (i2c_readbytes(state,state->config->demod_address,rec_buf,2)) {
- printk(KERN_WARNING "or51132: read_snr dvr read error\n");
- return -1;
- }
- snr_equ = rec_buf[0] | (rec_buf[1] << 8);
- dprintk("read_snr snr_equ %x %x (%i)\n",rec_buf[0],rec_buf[1],snr_equ);
-
- *snr = 0xFFFF - snr_equ;
- dprintk("read_snr %i\n",*snr);
+ *strength = state->snr / 8960;
return 0;
}
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