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-rw-r--r--drivers/media/tuners/r820t.c91
1 files changed, 91 insertions, 0 deletions
diff --git a/drivers/media/tuners/r820t.c b/drivers/media/tuners/r820t.c
index ed9cd6569548..0fa355d1737c 100644
--- a/drivers/media/tuners/r820t.c
+++ b/drivers/media/tuners/r820t.c
@@ -321,6 +321,20 @@ static int r820t_xtal_capacitor[][2] = {
};
/*
+ * measured with a Racal 6103E GSM test set at 928 MHz with -60 dBm
+ * input power, for raw results see:
+ * http://steve-m.de/projects/rtl-sdr/gain_measurement/r820t/
+ */
+
+static const int r820t_lna_gain_steps[] = {
+ 0, 9, 13, 40, 38, 13, 31, 22, 26, 31, 26, 14, 19, 5, 35, 13
+};
+
+static const int r820t_mixer_gain_steps[] = {
+ 0, 5, 10, 10, 19, 9, 10, 25, 17, 10, 8, 16, 13, 6, 3, -8
+};
+
+/*
* I2C read/write code and shadow registers logic
*/
static void shadow_store(struct r820t_priv *priv, u8 reg, const u8 *val,
@@ -1094,6 +1108,78 @@ static int r820t_read_gain(struct r820t_priv *priv)
return ((data[3] & 0x0f) << 1) + ((data[3] & 0xf0) >> 4);
}
+static int r820t_set_gain_mode(struct r820t_priv *priv,
+ bool set_manual_gain,
+ int gain)
+{
+ int rc;
+
+ if (set_manual_gain) {
+ int i, total_gain = 0;
+ uint8_t mix_index = 0, lna_index = 0;
+ u8 data[4];
+
+ /* LNA auto off */
+ rc = r820t_write_reg_mask(priv, 0x05, 0x10, 0x10);
+ if (rc < 0)
+ return rc;
+
+ /* Mixer auto off */
+ rc = r820t_write_reg_mask(priv, 0x07, 0, 0x10);
+ if (rc < 0)
+ return rc;
+
+ rc = r820_read(priv, 0x00, data, sizeof(data));
+ if (rc < 0)
+ return rc;
+
+ /* set fixed VGA gain for now (16.3 dB) */
+ rc = r820t_write_reg_mask(priv, 0x0c, 0x08, 0x9f);
+ if (rc < 0)
+ return rc;
+
+ for (i = 0; i < 15; i++) {
+ if (total_gain >= gain)
+ break;
+
+ total_gain += r820t_lna_gain_steps[++lna_index];
+
+ if (total_gain >= gain)
+ break;
+
+ total_gain += r820t_mixer_gain_steps[++mix_index];
+ }
+
+ /* set LNA gain */
+ rc = r820t_write_reg_mask(priv, 0x05, lna_index, 0x0f);
+ if (rc < 0)
+ return rc;
+
+ /* set Mixer gain */
+ rc = r820t_write_reg_mask(priv, 0x07, mix_index, 0x0f);
+ if (rc < 0)
+ return rc;
+ } else {
+ /* LNA */
+ rc = r820t_write_reg_mask(priv, 0x05, 0, 0xef);
+ if (rc < 0)
+ return rc;
+
+ /* Mixer */
+ rc = r820t_write_reg_mask(priv, 0x07, 0x10, 0xef);
+ if (rc < 0)
+ return rc;
+
+ /* set fixed VGA gain for now (26.5 dB) */
+ rc = r820t_write_reg_mask(priv, 0x0c, 0x0b, 0x9f);
+ if (rc < 0)
+ return rc;
+ }
+
+ return 0;
+}
+
+
static int generic_set_freq(struct dvb_frontend *fe,
u32 freq /* in HZ */,
unsigned bw,
@@ -1121,6 +1207,11 @@ static int generic_set_freq(struct dvb_frontend *fe,
rc = r820t_set_mux(priv, lo_freq);
if (rc < 0)
goto err;
+
+ rc = r820t_set_gain_mode(priv, true, 0);
+ if (rc < 0)
+ goto err;
+
rc = r820t_set_pll(priv, lo_freq);
if (rc < 0 || !priv->has_lock)
goto err;

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