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V4L/DVB (13331): mxl5005s: provide ability to override QAM gain for HVR-1600

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The HVR-1600 doesn't use the standard mechanism for computing the gain when
in QAM mode, instead always forcing it to be 0x02.  Provide the ability to
override the algorithm on a per-board basis.

This change results in an improvement of 0.4-0.6 dB for QAM tuning.

This work was sponsored by ONELAN Limited.

Cc: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Devin Heitmueller 2009-10-28 23:10:16 -03:00 committed by Mauro Carvalho Chehab
parent f0cd44b4a1
commit 48c511ed67
3 changed files with 9 additions and 1 deletions
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5
drivers/media/common/tuners/mxl5005s.c
View file

@ -2789,7 +2789,10 @@ static u16 MXL_TuneRF(struct dvb_frontend *fe, u32 RF_Freq)
/* add for 2.6.5 Special setting for QAM */
if (state->Mod_Type == MXL_QAM) {
if (state->RF_IN < 680000000)
if (state->config->qam_gain != 0)
status += MXL_ControlWrite(fe, RFSYN_CHP_GAIN,
state->config->qam_gain);
else if (state->RF_IN < 680000000)
status += MXL_ControlWrite(fe, RFSYN_CHP_GAIN, 3);
else
status += MXL_ControlWrite(fe, RFSYN_CHP_GAIN, 2);

4
drivers/media/common/tuners/mxl5005s.h
View file

@ -108,6 +108,10 @@ struct mxl5005s_config {
#define MXL_LOW_IF 1
u8 if_mode;
/* Some boards need to override the built-in logic for determining
the gain when in QAM mode (the HVR-1600 is one such case) */
u8 qam_gain;
/* Stuff I don't know what to do with */
u8 AgcMasterByte;
};

1
drivers/media/video/cx18/cx18-dvb.c
View file

@ -61,6 +61,7 @@ static struct mxl5005s_config hauppauge_hvr1600_tuner = {
.top = MXL5005S_TOP_25P2,
.mod_mode = MXL_DIGITAL_MODE,
.if_mode = MXL_ZERO_IF,
.qam_gain = 0x02,
.AgcMasterByte = 0x00,
};