[media] stb6100: Improve tuner performance

- Reduce the amount of white noise present, which causes the
  demodulator a significant time to acquire a frontend lock
  on a whole. Frontend shows a large significant improvement in
  performance.

Thanks to Peter Nayler for helping to identify the potential
hotspots and fixing them.

Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 127 insertions, 66 deletions

diff --git a/drivers/media/dvb/frontends/stb6100.c b/drivers/media/dvb/frontends/stb6100.c
index 80a9e4cba631..db66248fed46 100644
--- a/drivers/media/dvb/frontends/stb6100.c
+++ b/drivers/media/dvb/frontends/stb6100.c
@@ -51,7 +51,7 @@ module_param(verbose, int, 0644);
                 if (x > y)                                                              \
                         printk(format, ##arg);                                          \
         }                                                                               \
-} while(0)
+} while (0)
 
 struct stb6100_lkup {
         u32 val_low;
@@ -157,13 +157,25 @@ static int stb6100_read_reg(struct stb6100_state *state, u8 reg)
         u8 regs[STB6100_NUMREGS];
         int rc;
 
+        struct i2c_msg msg = {
+                .addr   = state->config->tuner_address + reg,
+                .flags  = I2C_M_RD,
+                .buf    = regs,
+                .len    = 1
+        };
+
+        rc = i2c_transfer(state->i2c, &msg, 1);
+
         if (unlikely(reg >= STB6100_NUMREGS)) {
                 dprintk(verbose, FE_ERROR, 1, "Invalid register offset 0x%x", reg);
                 return -EINVAL;
         }
-        if ((rc = stb6100_read_regs(state, regs)) < 0)
-                return rc;
-        return (unsigned int)regs[reg];
+        if (unlikely(verbose > FE_DEBUG)) {
+                dprintk(verbose, FE_DEBUG, 1, "    Read from 0x%02x", state->config->tuner_address);
+                dprintk(verbose, FE_DEBUG, 1, "        %s: 0x%02x", stb6100_regnames[reg], regs[0]);
+        }
+
+        return (unsigned int)regs[0];
 }
 
 static int stb6100_write_reg_range(struct stb6100_state *state, u8 buf[], int start, int len)
@@ -211,20 +223,17 @@ static int stb6100_write_reg(struct stb6100_state *state, u8 reg, u8 data)
         return stb6100_write_reg_range(state, &data, reg, 1);
 }
 
-static int stb6100_write_regs(struct stb6100_state *state, u8 regs[])
-{
-        stb6100_normalise_regs(regs);
-        return stb6100_write_reg_range(state, &regs[1], 1, STB6100_NUMREGS - 1);
-}
 
 static int stb6100_get_status(struct dvb_frontend *fe, u32 *status)
 {
         int rc;
         struct stb6100_state *state = fe->tuner_priv;
 
-        if ((rc = stb6100_read_reg(state, STB6100_LD)) < 0)
+        rc = stb6100_read_reg(state, STB6100_LD);
+        if (rc < 0) {
+                dprintk(verbose, FE_ERROR, 1, "%s failed", __func__);
                 return rc;
-
+        }
         return (rc & STB6100_LD_LOCK) ? TUNER_STATUS_LOCKED : 0;
 }
 
@@ -234,7 +243,8 @@ static int stb6100_get_bandwidth(struct dvb_frontend *fe, u32 *bandwidth)
         u8 f;
         struct stb6100_state *state = fe->tuner_priv;
 
-        if ((rc = stb6100_read_reg(state, STB6100_F)) < 0)
+        rc = stb6100_read_reg(state, STB6100_F);
+        if (rc < 0)
                 return rc;
         f = rc & STB6100_F_F;
 
@@ -265,14 +275,21 @@ static int stb6100_set_bandwidth(struct dvb_frontend *fe, u32 bandwidth)
         /* Turn on LPF bandwidth setting clock control,
          * set bandwidth, wait 10ms, turn off.
          */
-        if ((rc = stb6100_write_reg(state, STB6100_FCCK, 0x0d | STB6100_FCCK_FCCK)) < 0)
+        rc = stb6100_write_reg(state, STB6100_FCCK, 0x0d | STB6100_FCCK_FCCK);
+        if (rc < 0)
                 return rc;
-        if ((rc = stb6100_write_reg(state, STB6100_F, 0xc0 | tmp)) < 0)
+        rc = stb6100_write_reg(state, STB6100_F, 0xc0 | tmp);
+        if (rc < 0)
                 return rc;
-        msleep(1);
-        if ((rc = stb6100_write_reg(state, STB6100_FCCK, 0x0d)) < 0)
+
+        msleep(5);  /*  This is dangerous as another (related) thread may start */
+
+        rc = stb6100_write_reg(state, STB6100_FCCK, 0x0d);
+        if (rc < 0)
                 return rc;
 
+        msleep(10);  /*  This is dangerous as another (related) thread may start */
+
         return 0;
 }
 
@@ -284,7 +301,8 @@ static int stb6100_get_frequency(struct dvb_frontend *fe, u32 *frequency)
         struct stb6100_state *state = fe->tuner_priv;
         u8 regs[STB6100_NUMREGS];
 
-        if ((rc = stb6100_read_regs(state, regs)) < 0)
+        rc = stb6100_read_regs(state, regs);
+        if (rc < 0)
                 return rc;
 
         odiv = (regs[STB6100_VCO] & STB6100_VCO_ODIV) >> STB6100_VCO_ODIV_SHIFT;
@@ -312,8 +330,7 @@ static int stb6100_set_frequency(struct dvb_frontend *fe, u32 frequency)
         u8 regs[STB6100_NUMREGS];
         u8 g, psd2, odiv;
 
-        if ((rc = stb6100_read_regs(state, regs)) < 0)
-                return rc;
+        dprintk(verbose, FE_DEBUG, 1, "Version 2010-8-14 13:51");
 
         if (fe->ops.get_frontend) {
                 dprintk(verbose, FE_DEBUG, 1, "Get frontend parameters");
@@ -321,96 +338,140 @@ static int stb6100_set_frequency(struct dvb_frontend *fe, u32 frequency)
         }
         srate = p.u.qpsk.symbol_rate;
 
-        regs[STB6100_DLB] = 0xdc;
-        /* Disable LPEN */
-        regs[STB6100_LPEN] &= ~STB6100_LPEN_LPEN; /* PLL Loop disabled */
+        /* Set up tuner cleanly, LPF calibration on */
+        rc = stb6100_write_reg(state, STB6100_FCCK, 0x4d | STB6100_FCCK_FCCK);
+        if (rc < 0)
+                return rc;  /* allow LPF calibration */
 
-        if ((rc = stb6100_write_regs(state, regs)) < 0)
+        /* PLL Loop disabled, bias on, VCO on, synth on */
+        regs[STB6100_LPEN] = 0xeb;
+        rc = stb6100_write_reg(state, STB6100_LPEN, regs[STB6100_LPEN]);
+        if (rc < 0)
                 return rc;
 
-        /* Baseband gain.       */
-        if (srate >= 15000000)
-                g = 9;  //  +4 dB
-        else if (srate >= 5000000)
-                g = 11; //  +8 dB
-        else
-                g = 14; // +14 dB
-
-        regs[STB6100_G] = (regs[STB6100_G] & ~STB6100_G_G) | g;
-        regs[STB6100_G] &= ~STB6100_G_GCT; /* mask GCT */
-        regs[STB6100_G] |= (1 << 5); /* 2Vp-p Mode */
+        /* Program the registers with their data values */
 
         /* VCO divide ratio (LO divide ratio, VCO prescaler enable).    */
         if (frequency <= 1075000)
                 odiv = 1;
         else
                 odiv = 0;
-        regs[STB6100_VCO] = (regs[STB6100_VCO] & ~STB6100_VCO_ODIV) | (odiv << STB6100_VCO_ODIV_SHIFT);
 
-        if ((frequency > 1075000) && (frequency <= 1325000))
-                psd2 = 0;
-        else
-                psd2 = 1;
-        regs[STB6100_K] = (regs[STB6100_K] & ~STB6100_K_PSD2) | (psd2 << STB6100_K_PSD2_SHIFT);
+        /* VCO enabled, seach clock off as per LL3.7, 3.4.1 */
+        regs[STB6100_VCO] = 0xe0 | (odiv << STB6100_VCO_ODIV_SHIFT);
 
         /* OSM  */
         for (ptr = lkup;
              (ptr->val_high != 0) && !CHKRANGE(frequency, ptr->val_low, ptr->val_high);
              ptr++);
+
         if (ptr->val_high == 0) {
                 printk(KERN_ERR "%s: frequency out of range: %u kHz\n", __func__, frequency);
                 return -EINVAL;
         }
         regs[STB6100_VCO] = (regs[STB6100_VCO] & ~STB6100_VCO_OSM) | ptr->reg;
+        rc = stb6100_write_reg(state, STB6100_VCO, regs[STB6100_VCO]);
+        if (rc < 0)
+                return rc;
 
+        if ((frequency > 1075000) && (frequency <= 1325000))
+                psd2 = 0;
+        else
+                psd2 = 1;
         /* F(VCO) = F(LO) * (ODIV == 0 ? 2 : 4)                 */
         fvco = frequency << (1 + odiv);
         /* N(I) = floor(f(VCO) / (f(XTAL) * (PSD2 ? 2 : 1)))    */
         nint = fvco / (state->reference << psd2);
         /* N(F) = round(f(VCO) / f(XTAL) * (PSD2 ? 2 : 1) - N(I)) * 2 ^ 9       */
         nfrac = DIV_ROUND_CLOSEST((fvco - (nint * state->reference << psd2))
-                                         << (9 - psd2),
-                                  state->reference);
+                                         << (9 - psd2), state->reference);
+
+        /* NI */
+        regs[STB6100_NI] = nint;
+        rc = stb6100_write_reg(state, STB6100_NI, regs[STB6100_NI]);
+        if (rc < 0)
+                return rc;
+
+        /* NF */
+        regs[STB6100_NF_LSB] = nfrac;
+        rc = stb6100_write_reg(state, STB6100_NF_LSB, regs[STB6100_NF_LSB]);
+        if (rc < 0)
+                return rc;
+
+        /* K */
+        regs[STB6100_K] = (0x38 & ~STB6100_K_PSD2) | (psd2 << STB6100_K_PSD2_SHIFT);
+        regs[STB6100_K] = (regs[STB6100_K] & ~STB6100_K_NF_MSB) | ((nfrac >> 8) & STB6100_K_NF_MSB);
+        rc = stb6100_write_reg(state, STB6100_K, regs[STB6100_K]);
+        if (rc < 0)
+                return rc;
+
+        /* G Baseband gain. */
+        if (srate >= 15000000)
+                g = 9;  /*  +4 dB */
+        else if (srate >= 5000000)
+                g = 11; /*  +8 dB */
+        else
+                g = 14; /* +14 dB */
+
+        regs[STB6100_G] = (0x10 & ~STB6100_G_G) | g;
+        regs[STB6100_G] &= ~STB6100_G_GCT; /* mask GCT */
+        regs[STB6100_G] |= (1 << 5); /* 2Vp-p Mode */
+        rc = stb6100_write_reg(state, STB6100_G, regs[STB6100_G]);
+        if (rc < 0)
+                return rc;
+
+        /* F we don't write as it is set up in BW set */
+
+        /* DLB set DC servo loop BW to 160Hz (LLA 3.8 / 2.1) */
+        regs[STB6100_DLB] = 0xcc;
+        rc = stb6100_write_reg(state, STB6100_DLB, regs[STB6100_DLB]);
+        if (rc < 0)
+                return rc;
+
         dprintk(verbose, FE_DEBUG, 1,
                 "frequency = %u, srate = %u, g = %u, odiv = %u, psd2 = %u, fxtal = %u, osm = %u, fvco = %u, N(I) = %u, N(F) = %u",
                 frequency, srate, (unsigned int)g, (unsigned int)odiv,
                 (unsigned int)psd2, state->reference,
                 ptr->reg, fvco, nint, nfrac);
-        regs[STB6100_NI] = nint;
-        regs[STB6100_NF_LSB] = nfrac;
-        regs[STB6100_K] = (regs[STB6100_K] & ~STB6100_K_NF_MSB) | ((nfrac >> 8) & STB6100_K_NF_MSB);
-        regs[STB6100_VCO] |= STB6100_VCO_OSCH;          /* VCO search enabled           */
-        regs[STB6100_VCO] |= STB6100_VCO_OCK;           /* VCO search clock off         */
-        regs[STB6100_FCCK] |= STB6100_FCCK_FCCK;        /* LPF BW setting clock enabled */
-        regs[STB6100_LPEN] &= ~STB6100_LPEN_LPEN;       /* PLL loop disabled            */
-        /* Power up. */
-        regs[STB6100_LPEN] |= STB6100_LPEN_SYNP | STB6100_LPEN_OSCP | STB6100_LPEN_BEN;
 
-        msleep(2);
-        if ((rc = stb6100_write_regs(state, regs)) < 0)
+        /* Set up the test registers */
+        regs[STB6100_TEST1] = 0x8f;
+        rc = stb6100_write_reg(state, STB6100_TEST1, regs[STB6100_TEST1]);
+        if (rc < 0)
+                return rc;
+        regs[STB6100_TEST3] = 0xde;
+        rc = stb6100_write_reg(state, STB6100_TEST3, regs[STB6100_TEST3]);
+        if (rc < 0)
                 return rc;
 
-        msleep(2);
-        regs[STB6100_LPEN] |= STB6100_LPEN_LPEN;        /* PLL loop enabled             */
-        if ((rc = stb6100_write_reg(state, STB6100_LPEN, regs[STB6100_LPEN])) < 0)
+        /* Bring up tuner according to LLA 3.7 3.4.1, step 2 */
+        regs[STB6100_LPEN] = 0xfb; /* PLL Loop enabled, bias on, VCO on, synth on */
+        rc = stb6100_write_reg(state, STB6100_LPEN, regs[STB6100_LPEN]);
+        if (rc < 0)
                 return rc;
 
+        msleep(2);
+
+        /* Bring up tuner according to LLA 3.7 3.4.1, step 3 */
         regs[STB6100_VCO] &= ~STB6100_VCO_OCK;          /* VCO fast search              */
-        if ((rc = stb6100_write_reg(state, STB6100_VCO, regs[STB6100_VCO])) < 0)
+        rc = stb6100_write_reg(state, STB6100_VCO, regs[STB6100_VCO]);
+        if (rc < 0)
                 return rc;
 
-        msleep(10);                                     /* wait for LO to lock          */
+        msleep(10);  /*  This is dangerous as another (related) thread may start */ /* wait for LO to lock */
+
         regs[STB6100_VCO] &= ~STB6100_VCO_OSCH;         /* vco search disabled          */
         regs[STB6100_VCO] |= STB6100_VCO_OCK;           /* search clock off             */
-        if ((rc = stb6100_write_reg(state, STB6100_VCO, regs[STB6100_VCO])) < 0)
-                return rc;
-        regs[STB6100_FCCK] &= ~STB6100_FCCK_FCCK;       /* LPF BW clock disabled        */
-        stb6100_normalise_regs(regs);
-        if ((rc = stb6100_write_reg_range(state, &regs[1], 1, STB6100_NUMREGS - 3)) < 0)
+        rc = stb6100_write_reg(state, STB6100_VCO, regs[STB6100_VCO]);
+        if (rc < 0)
                 return rc;
 
-        msleep(100);
+        rc = stb6100_write_reg(state, STB6100_FCCK, 0x0d);
+        if (rc < 0)
+                return rc;  /* Stop LPF calibration */
 
+        msleep(10);  /*  This is dangerous as another (related) thread may start */
+                     /* wait for stabilisation, (should not be necessary)               */
         return 0;
 }
 
@@ -433,8 +494,8 @@ static int stb6100_init(struct dvb_frontend *fe)
         state->bandwidth        = status->bandwidth * 1000;     /* Hz   */
         state->reference        = status->refclock / 1000;      /* kHz  */
 
-        /* Set default bandwidth.       */
-        return stb6100_set_bandwidth(fe, state->bandwidth);
+        /* Set default bandwidth. Modified, PN 13-May-10        */
+        return 0;
 }
 
 static int stb6100_get_state(struct dvb_frontend *fe,