diff options
Diffstat (limited to 'drivers/media/common')
| -rw-r--r-- | drivers/media/common/tuners/xc5000.c | 32 |
1 files changed, 26 insertions, 6 deletions
diff --git a/drivers/media/common/tuners/xc5000.c b/drivers/media/common/tuners/xc5000.c index 1e28f7dcb26b..aa1b2e844d32 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 { |