Re: [PATCH 9/9] lgdt3306a: Add QAM AUTO support

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On Thu, Jan 4, 2018 at 7:04 PM, Brad Love <brad@xxxxxxxxxxxxxxxx> wrote:
> As configured currently, modulation in the driver is set to auto detect,
> no matter what the user sets modulation to. This leads to both QAM64
> and QAM256 having the same effect. QAM AUTO is explicitly added here for
> compatibility with scanning software who can use AUTO instead of doing
> essentially the same scan twice.
> Also included is a module option to enforce a specific QAM modulation if
> desired. The true modulation is read before calculating the snr.
> Changes are backwards compatible with current behaviour.
>
> Signed-off-by: Brad Love <brad@xxxxxxxxxxxxxxxx>

:+1

Reviewed-by: Michael Ira Krufky <mkrufky@xxxxxxxxxxx>

> ---
>  drivers/media/dvb-frontends/lgdt3306a.c | 42 ++++++++++++++++++++++++++-------
>  1 file changed, 33 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/media/dvb-frontends/lgdt3306a.c b/drivers/media/dvb-frontends/lgdt3306a.c
> index 2f540f1..111efb0 100644
> --- a/drivers/media/dvb-frontends/lgdt3306a.c
> +++ b/drivers/media/dvb-frontends/lgdt3306a.c
> @@ -30,6 +30,17 @@ static int debug;
>  module_param(debug, int, 0644);
>  MODULE_PARM_DESC(debug, "set debug level (info=1, reg=2 (or-able))");
>
> +/*
> + * Older drivers treated QAM64 and QAM256 the same; that is the HW always
> + * used "Auto" mode during detection.  Setting "forced_manual"=1 allows
> + * the user to treat these modes as separate.  For backwards compatibility,
> + * it's off by default.  QAM_AUTO can now be specified to achive that
> + * effect even if "forced_manual"=1
> + */
> +static int forced_manual;
> +module_param(forced_manual, int, 0644);
> +MODULE_PARM_DESC(forced_manual, "if set, QAM64 and QAM256 will only lock to modulation specified");
> +
>  #define DBG_INFO 1
>  #define DBG_REG  2
>  #define DBG_DUMP 4 /* FGR - comment out to remove dump code */
> @@ -566,7 +577,12 @@ static int lgdt3306a_set_qam(struct lgdt3306a_state *state, int modulation)
>         /* 3. : 64QAM/256QAM detection(manual, auto) */
>         ret = lgdt3306a_read_reg(state, 0x0009, &val);
>         val &= 0xfc;
> -       val |= 0x02; /* STDOPDETCMODE[1:0]=1=Manual 2=Auto */
> +       /* Check for forced Manual modulation modes; otherwise always "auto" */
> +       if(forced_manual && (modulation != QAM_AUTO)){
> +               val |= 0x01; /* STDOPDETCMODE[1:0]= 1=Manual */
> +       } else {
> +               val |= 0x02; /* STDOPDETCMODE[1:0]= 2=Auto */
> +       }
>         ret = lgdt3306a_write_reg(state, 0x0009, val);
>         if (lg_chkerr(ret))
>                 goto fail;
> @@ -642,10 +658,9 @@ static int lgdt3306a_set_modulation(struct lgdt3306a_state *state,
>                 ret = lgdt3306a_set_vsb(state);
>                 break;
>         case QAM_64:
> -               ret = lgdt3306a_set_qam(state, QAM_64);
> -               break;
>         case QAM_256:
> -               ret = lgdt3306a_set_qam(state, QAM_256);
> +       case QAM_AUTO:
> +               ret = lgdt3306a_set_qam(state, p->modulation);
>                 break;
>         default:
>                 return -EINVAL;
> @@ -672,6 +687,7 @@ static int lgdt3306a_agc_setup(struct lgdt3306a_state *state,
>                 break;
>         case QAM_64:
>         case QAM_256:
> +       case QAM_AUTO:
>                 break;
>         default:
>                 return -EINVAL;
> @@ -726,6 +742,7 @@ static int lgdt3306a_spectral_inversion(struct lgdt3306a_state *state,
>                 break;
>         case QAM_64:
>         case QAM_256:
> +       case QAM_AUTO:
>                 /* Auto ok for QAM */
>                 ret = lgdt3306a_set_inversion_auto(state, 1);
>                 break;
> @@ -749,6 +766,7 @@ static int lgdt3306a_set_if(struct lgdt3306a_state *state,
>                 break;
>         case QAM_64:
>         case QAM_256:
> +       case QAM_AUTO:
>                 if_freq_khz = state->cfg->qam_if_khz;
>                 break;
>         default:
> @@ -1607,6 +1625,7 @@ static int lgdt3306a_read_status(struct dvb_frontend *fe,
>                 switch (state->current_modulation) {
>                 case QAM_256:
>                 case QAM_64:
> +               case QAM_AUTO:
>                         if (lgdt3306a_qam_lock_poll(state) == LG3306_LOCK) {
>                                 *status |= FE_HAS_VITERBI;
>                                 *status |= FE_HAS_SYNC;
> @@ -1650,6 +1669,7 @@ static int lgdt3306a_read_signal_strength(struct dvb_frontend *fe,
>          * Calculate some sort of "strength" from SNR
>          */
>         struct lgdt3306a_state *state = fe->demodulator_priv;
> +       u8 val;
>         u16 snr; /* snr_x10 */
>         int ret;
>         u32 ref_snr; /* snr*100 */
> @@ -1662,11 +1682,15 @@ static int lgdt3306a_read_signal_strength(struct dvb_frontend *fe,
>                  ref_snr = 1600; /* 16dB */
>                  break;
>         case QAM_64:
> -                ref_snr = 2200; /* 22dB */
> -                break;
>         case QAM_256:
> -                ref_snr = 2800; /* 28dB */
> -                break;
> +       case QAM_AUTO:
> +               /* need to know actual modulation to set proper SNR baseline */
> +               lgdt3306a_read_reg(state, 0x00a6, &val);
> +               if(val & 0x04)
> +                       ref_snr = 2800; /* QAM-256 28dB */
> +               else
> +                       ref_snr = 2200; /* QAM-64  22dB */
> +               break;
>         default:
>                 return -EINVAL;
>         }
> @@ -2136,7 +2160,7 @@ static const struct dvb_frontend_ops lgdt3306a_ops = {
>                 .frequency_min      = 54000000,
>                 .frequency_max      = 858000000,
>                 .frequency_stepsize = 62500,
> -               .caps = FE_CAN_QAM_64 | FE_CAN_QAM_256 | FE_CAN_8VSB
> +               .caps = FE_CAN_QAM_AUTO | FE_CAN_QAM_64 | FE_CAN_QAM_256 | FE_CAN_8VSB
>         },
>         .i2c_gate_ctrl        = lgdt3306a_i2c_gate_ctrl,
>         .init                 = lgdt3306a_init,
> --
> 2.7.4
>



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