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Message-ID: <5912d64a-3f69-44ad-9b06-9e02019141e6@quicinc.com>
Date: Tue, 7 May 2024 19:06:36 +0800
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Subject: Re: [PATCH v4 1/3] wifi: ath12k: report station mode transmit rate
To: Kalle Valo <kvalo@kernel.org>
CC: <ath12k@lists.infradead.org>, <linux-wireless@vger.kernel.org>
References: <20240419032122.7009-1-quic_lingbok@quicinc.com>
 <20240419032122.7009-2-quic_lingbok@quicinc.com> <87r0etsp6u.fsf@kernel.org>
 <c01db4fc-03a0-41f6-9f16-bfa3b2c08007@quicinc.com>
 <87r0esqsd6.fsf@kernel.org>
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From: Lingbo Kong <quic_lingbok@quicinc.com>
In-Reply-To: <87r0esqsd6.fsf@kernel.org>
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On 2024/4/26 19:24, Kalle Valo wrote:
> Lingbo Kong <quic_lingbok@quicinc.com> writes:
> 
>> On 2024/4/25 18:37, Kalle Valo wrote:
>>> Lingbo Kong <quic_lingbok@quicinc.com> writes:
>>>
>>>> Currently, the transmit rate of "iw dev xxx station dump" command
>>>> always show an invalid value.
>>>>
>>>> To address this issue, ath12k parse the info of transmit complete
>>>> report from firmware and indicate the transmit rate to mac80211.
>>>>
>>>> This patch affects the station mode of WCN7850 and QCN9274.
>>>>
>>>> After that, "iw dev xxx station dump" show the correct transmit rate.
>>>> Such as:
>>>>
>>>> Station 00:03:7f:12:03:03 (on wlo1)
>>>>           inactive time:  872 ms
>>>>           rx bytes:       219111
>>>>           rx packets:     1133
>>>>           tx bytes:       53767
>>>>           tx packets:     462
>>>>           tx retries:     51
>>>>           tx failed:      0
>>>>           beacon loss:    0
>>>>           beacon rx:      403
>>>>           rx drop misc:   74
>>>>           signal:         -95 dBm
>>>>           beacon signal avg:      -18 dBm
>>>>           tx bitrate:     1441.1 MBit/s 80MHz EHT-MCS 13 EHT-NSS 2 EHT-GI 0
>>>>
>>>> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
>>>> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.2.1-00201-QCAHKSWPL_SILICONZ-1
>>>>
>>>> Signed-off-by: Lingbo Kong <quic_lingbok@quicinc.com>
>>> [...]
>>>
>>>> +static void ath12k_dp_tx_update(struct ath12k *ar, struct hal_tx_status *ts)
>>>> +{
>>>> +	if (ar->last_ppdu_id != 0) {
>>>> +		if (ar->last_ppdu_id == ts->ppdu_id ||
>>>> +		    ar->cached_ppdu_id == ar->last_ppdu_id)
>>>> +			ar->cached_ppdu_id = ar->last_ppdu_id;
>>>> +
>>>> +		ath12k_dp_tx_update_txcompl(ar, ts);
>>>> +	}
>>>> +
>>>> +	ar->last_ppdu_id = ts->ppdu_id;
>>>> +}
>>> A code comment would help a lot. Why is ar->cached_ppdu_id needed
>>> here?
>>> And if 'ar->cached_ppdu_id == ar->last_ppdu_id' is true why do then
>>> do
>>> 'ar->cached_ppdu_id = ar->last_ppdu_id'? The value of ar->cached_ppdu_id
>>> is not changing here (unless I'm missing something).
>>> Also I'm worried about locking. How is access to ar->last_ppdu_id
>>> and
>>> ar->cached_ppdu_id protected?
>>>
>>
>> Thanks for pointing to this.
>> you're right, the ar->cached_ppdu_id haven't used in here, so need to
>> delete it.
>> i missed something in here.
>>
>> So, change the ath12k_dp_tx_update(struct ath12k *ar, struct
>> hal_tx_status *ts) to
>> static void ath12k_dp_tx_update(struct ath12k *ar, struct hal_tx_status *ts)
>> {
>> 	if (ts->flags & HAL_TX_STATUS_FLAGS_FIRST_MSDU) {
>> 		if (ar->last_ppdu_id != 0)
>> 			ath12k_dp_tx_update_txcompl(ar, ts);
>> 		ar->last_ppdu_id = ts->ppdu_id;
>> 	}
>> }
> 
> Access to ar->last_ppdu_id still looks racy to me.
> 
> And why do we need to track last_ppdu_id? I don't have time to start
> investigating that right now, a code comment explaining that would help
> a lot.

yes, you are right, kalle, thanks for pointing of this.
There really isn't a need to add a judgement of last_ppdu_id to this place.

The ath12k_dp_tx_update_txcompl() function should be called directly and 
no need to define ath12k_dp_tx_update() function.

Best regards
Lingbo Kong