[PATCH 3/3] ath9k: add noise floor override option

[Janusz Dziedzic]

On 16 March 2017 at 16:13, Simon Wunderlich <sw at simonwunderlich.de> wrote:
> Introduce a debugfs option to manually override the noise floor,
> ignoring the automatically tuned noise floor of the driver/hw.
>
> In my tests with a AR9580 based module and a tx99 5 MHz interferer,
> I could tune the noisefloor to -95 dBm or above to allow communication
> again. The automatic noise floor calibration sometimes could adapt to
> the situation as well, but not reliably and permanently.
>
> I would consider this "feature" experimental and interesting for people
> debugging the noise floor calibration or other effects of the hardware.
>
> Signed-off-by: Simon Wunderlich <sw at simonwunderlich.de>
> Signed-off-by: Mathias Kretschmer <mathias.kretschmer at fit.fraunhofer.de>
> ---
>  drivers/net/wireless/ath/ath9k/calib.c |  5 ++-
>  drivers/net/wireless/ath/ath9k/debug.c | 62 ++++++++++++++++++++++++++++++++++
>  drivers/net/wireless/ath/ath9k/hw.h    |  1 +
>  3 files changed, 67 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/ath/ath9k/calib.c b/drivers/net/wireless/ath/ath9k/calib.c
> index 0f71146b781d..13ab6bc46775 100644
> --- a/drivers/net/wireless/ath/ath9k/calib.c
> +++ b/drivers/net/wireless/ath/ath9k/calib.c
> @@ -254,7 +254,9 @@ int ath9k_hw_loadnf(struct ath_hw *ah, struct ath9k_channel *chan)
>                         if ((i >= AR5416_MAX_CHAINS) && !IS_CHAN_HT40(chan))
>                                 continue;
>
> -                       if (h)
> +                       if (ah->nf_override)
> +                               nfval = ah->nf_override;
> +                       else if (h)
>                                 nfval = h[i].privNF;
>                         else
>                                 nfval = default_nf;
> @@ -348,6 +350,7 @@ int ath9k_hw_loadnf(struct ath_hw *ah, struct ath9k_channel *chan)
>
>         return 0;
>  }
> +EXPORT_SYMBOL(ath9k_hw_loadnf);
>
>
>  static void ath9k_hw_nf_sanitize(struct ath_hw *ah, s16 *nf)
> diff --git a/drivers/net/wireless/ath/ath9k/debug.c b/drivers/net/wireless/ath/ath9k/debug.c
> index 43930c336987..2e64977a8ab6 100644
> --- a/drivers/net/wireless/ath/ath9k/debug.c
> +++ b/drivers/net/wireless/ath/ath9k/debug.c
> @@ -1191,6 +1191,65 @@ static const struct file_operations fops_tpc = {
>         .llseek = default_llseek,
>  };
>
> +static ssize_t read_file_nf_override(struct file *file,
> +                                    char __user *user_buf,
> +                                    size_t count, loff_t *ppos)
> +{
> +       struct ath_softc *sc = file->private_data;
> +       struct ath_hw *ah = sc->sc_ah;
> +       char buf[32];
> +       unsigned int len;
> +
> +       if (ah->nf_override == 0)
> +               len = sprintf(buf, "off\n");
> +       else
> +               len = sprintf(buf, "%d\n", ah->nf_override);
> +
> +       return simple_read_from_buffer(user_buf, count, ppos, buf, len);
> +}
> +
> +static ssize_t write_file_nf_override(struct file *file,
> +                                     const char __user *user_buf,
> +                                     size_t count, loff_t *ppos)
> +{
> +       struct ath_softc *sc = file->private_data;
> +       struct ath_hw *ah = sc->sc_ah;
> +       long val;
> +       char buf[32];
> +       ssize_t len;
> +
> +       len = min(count, sizeof(buf) - 1);
> +       if (copy_from_user(buf, user_buf, len))
> +               return -EFAULT;
> +
> +       buf[len] = '\0';
> +       if (strncmp("off", buf, 3) == 0)
> +               val = 0;
> +       else if (kstrtol(buf, 0, &val))
> +               return -EINVAL;
> +
> +       if (val > 0)
> +               return -EINVAL;
> +
> +       if (val < -120)
> +               return -EINVAL;
> +
> +       ah->nf_override = val;
> +
> +       if (ah->curchan)
> +               ath9k_hw_loadnf(ah, ah->curchan);
> +
> +       return count;
> +}
> +
> +static const struct file_operations fops_nf_override = {
> +       .read = read_file_nf_override,
> +       .write = write_file_nf_override,
> +       .open = simple_open,
> +       .owner = THIS_MODULE,
> +       .llseek = default_llseek,
> +};
> +
>  /* Ethtool support for get-stats */
>
>  #define AMKSTR(nm) #nm "_BE", #nm "_BK", #nm "_VI", #nm "_VO"
> @@ -1402,5 +1461,8 @@ int ath9k_init_debug(struct ath_hw *ah)
>         debugfs_create_u16("airtime_flags", S_IRUSR | S_IWUSR,
>                            sc->debug.debugfs_phy, &sc->airtime_flags);
>
> +       debugfs_create_file("nf_override", S_IRUSR | S_IWUSR,
> +                           sc->debug.debugfs_phy, sc, &fops_nf_override);
> +

Why not simply:
        debugfs_create_u32("nf_override", S_IRUSR|S_IWUSR ,
sc->debug.debugfs_phy,
                          &ah->nf_override);

One line patch :)

>         return 0;
>  }
> diff --git a/drivers/net/wireless/ath/ath9k/hw.h b/drivers/net/wireless/ath/ath9k/hw.h
> index 496e3cd1b509..eba478f052b9 100644
> --- a/drivers/net/wireless/ath/ath9k/hw.h
> +++ b/drivers/net/wireless/ath/ath9k/hw.h
> @@ -803,6 +803,7 @@ struct ath_hw {
>         u32 rfkill_gpio;
>         u32 rfkill_polarity;
>         u32 ah_flags;
> +       s16 nf_override;
>
>         bool reset_power_on;
>         bool htc_reset_init;
> --
> 2.11.0
>
>
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