linux-kernel - Re: [PATCH v2 2/2] wcn36xx: fix RX BD rate mapping for 5GHz legacy rates

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Message-ID: <CAMZdPi8c1aJCCL8b6iYSz1Ev46jK15Fpa9pG-2FGhrT3FR2RMA@mail.gmail.com>
Date:   Wed, 3 Nov 2021 18:08:15 +0100
From:   Loic Poulain <loic.poulain@...aro.org>
To:     Benjamin Li <benl@...areup.com>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>,
        linux-arm-msm@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, wcn36xx@...ts.infradead.org,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] wcn36xx: fix RX BD rate mapping for 5GHz legacy rates

Hi Ben,

On Wed, 3 Nov 2021 at 16:56, Benjamin Li <benl@...areup.com> wrote:
>
> The linear mapping between the BD rate field and the driver's 5GHz
> legacy rates table (wcn_5ghz_rates) does not only apply for the latter
> four rates -- it applies to all eight rates.
>
> Fixes: 6ea131acea98 ("wcn36xx: Fix warning due to bad rate_idx")
> Signed-off-by: Benjamin Li <benl@...areup.com>
> ---
>  drivers/net/wireless/ath/wcn36xx/txrx.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/wcn36xx/txrx.c b/drivers/net/wireless/ath/wcn36xx/txrx.c
> index f0a9f069a92a9..fce3a6a98f596 100644
> --- a/drivers/net/wireless/ath/wcn36xx/txrx.c
> +++ b/drivers/net/wireless/ath/wcn36xx/txrx.c
> @@ -272,7 +272,6 @@ int wcn36xx_rx_skb(struct wcn36xx *wcn, struct sk_buff *skb)
>         const struct wcn36xx_rate *rate;
>         struct ieee80211_hdr *hdr;
>         struct wcn36xx_rx_bd *bd;
> -       struct ieee80211_supported_band *sband;
>         u16 fc, sn;
>
>         /*
> @@ -350,12 +349,10 @@ int wcn36xx_rx_skb(struct wcn36xx *wcn, struct sk_buff *skb)
>                 status.enc_flags = rate->encoding_flags;
>                 status.bw = rate->bw;
>                 status.rate_idx = rate->mcs_or_legacy_index;
> -               sband = wcn->hw->wiphy->bands[status.band];
>                 status.nss = 1;
>
>                 if (status.band == NL80211_BAND_5GHZ &&
> -                   status.encoding == RX_ENC_LEGACY &&
> -                   status.rate_idx >= sband->n_bitrates) {


It looks fine, but can you replace it with a 'status.rate_idx  >= 4'.
I get sporadic 5Ghz frames reported with rate_idx=0 (firmware miss?),
leading to warnings because status.rate_idx is -4(unsigned) in that
case. So better to report a wrong rate than a corrupted one.

>
> +                   status.encoding == RX_ENC_LEGACY) {
>                         /* no dsss rates in 5Ghz rates table */
>                         status.rate_idx -= 4;
>                 }
> --


Regards,
Loic