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path: root/drivers/media/common/tuners/xc5000.c
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Diffstat (limited to 'drivers/media/common/tuners/xc5000.c')
-rw-r--r--drivers/media/common/tuners/xc5000.c32
1 files changed, 26 insertions, 6 deletions
diff --git a/drivers/media/common/tuners/xc5000.c b/drivers/media/common/tuners/xc5000.c
index 1e28f7dcb26..aa1b2e844d3 100644
--- a/drivers/media/common/tuners/xc5000.c
+++ b/drivers/media/common/tuners/xc5000.c
@@ -628,6 +628,15 @@ static void xc_debug_dump(struct xc5000_priv *priv)
dprintk(1, "*** Quality (0:<8dB, 7:>56dB) = %d\n", quality);
}
+/*
+ * As defined on EN 300 429, the DVB-C roll-off factor is 0.15.
+ * So, the amount of the needed bandwith is given by:
+ * Bw = Symbol_rate * (1 + 0.15)
+ * As such, the maximum symbol rate supported by 6 MHz is given by:
+ * max_symbol_rate = 6 MHz / 1.15 = 5217391 Bauds
+ */
+#define MAX_SYMBOL_RATE_6MHz 5217391
+
static int xc5000_set_params(struct dvb_frontend *fe,
struct dvb_frontend_parameters *params)
{
@@ -688,21 +697,32 @@ static int xc5000_set_params(struct dvb_frontend *fe,
}
priv->rf_mode = XC_RF_MODE_AIR;
} else if (fe->ops.info.type == FE_QAM) {
- dprintk(1, "%s() QAM\n", __func__);
switch (params->u.qam.modulation) {
+ case QAM_256:
+ case QAM_AUTO:
case QAM_16:
case QAM_32:
case QAM_64:
case QAM_128:
- case QAM_256:
- case QAM_AUTO:
dprintk(1, "%s() QAM modulation\n", __func__);
- priv->bandwidth = BANDWIDTH_8_MHZ;
- priv->video_standard = DTV7_8;
- priv->freq_hz = params->frequency - 2750000;
priv->rf_mode = XC_RF_MODE_CABLE;
+ /*
+ * Using a 8MHz bandwidth sometimes fail
+ * with 6MHz-spaced channels, due to inter-carrier
+ * interference. So, use DTV6 firmware
+ */
+ if (params->u.qam.symbol_rate <= MAX_SYMBOL_RATE_6MHz) {
+ priv->bandwidth = BANDWIDTH_6_MHZ;
+ priv->video_standard = DTV6;
+ priv->freq_hz = params->frequency - 1750000;
+ } else {
+ priv->bandwidth = BANDWIDTH_8_MHZ;
+ priv->video_standard = DTV7_8;
+ priv->freq_hz = params->frequency - 2750000;
+ }
break;
default:
+ dprintk(1, "%s() Unsupported QAM type\n", __func__);
return -EINVAL;
}
} else {