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Message-ID: <a07a490f-3611-4e03-8ea4-7ce9fc4e3889@quicinc.com>
Date: Tue, 11 Jun 2024 12:15:59 +0530
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Subject: Re: [PATCH] wifi: ath12k: modify remain on channel for single wiphy
To: Kalle Valo <kvalo@kernel.org>
CC: <ath12k@lists.infradead.org>, <linux-wireless@vger.kernel.org>
References: <20240528082739.1226758-1-quic_ramess@quicinc.com>
 <878qzcq4uc.fsf@kernel.org>
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From: Rameshkumar Sundaram <quic_ramess@quicinc.com>
In-Reply-To: <878qzcq4uc.fsf@kernel.org>
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On 6/10/2024 7:26 PM, Kalle Valo wrote:
> Rameshkumar Sundaram <quic_ramess@quicinc.com> writes:
> 
>> When multiple radios are advertised as a single wiphy which
>> supports various bands, vdev creation for the vif is deferred
>> until channel is assigned to it.
>> If a remain on channel(RoC) request is received from mac80211,
>> select the corresponding radio(ar) based on channel and create
>> a vdev on that radio to initiate an RoC scan.
>>
>> Note that on RoC completion this vdev is not deleted. If a new
>> RoC/hw scan request is seen on that same vif for a different band the
>> vdev will be deleted and created on the new radio supporting the
>> request.
>>
>> Also if the RoC scan is requested when the vdev is in started state,
>> no switching to new radio is allowed and RoC request can be accepted
>> only on channels within same radio.
>>
>> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1
>> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
>>
>> Signed-off-by: Rameshkumar Sundaram <quic_ramess@quicinc.com>
> 
> I did some white space changes to the commit message.
> 
>> @@ -8416,12 +8416,63 @@ static int ath12k_mac_op_remain_on_channel(struct ieee80211_hw *hw,
>>   	struct ath12k_vif *arvif = ath12k_vif_to_arvif(vif);
>>   	struct ath12k_hw *ah = ath12k_hw_to_ah(hw);
>>   	struct ath12k_wmi_scan_req_arg arg;
>> -	struct ath12k *ar;
>> +	struct ath12k *ar, *prev_ar;
>>   	u32 scan_time_msec;
>> +	bool create = true;
>>   	int ret;
>>   
>> -	ar = ath12k_ah_to_ar(ah, 0);
>> +	if (ah->num_radio == 1) {
>> +		WARN_ON(!arvif->is_created);
>> +		ar = ath12k_ah_to_ar(ah, 0);
>> +		goto scan;
>> +	}
>> +
>> +	ar = ath12k_mac_select_scan_device(hw, vif, chan->center_freq);
>> +	if (!ar)
>> +		return -EINVAL;
>> +
>> +	/* If the vif is already assigned to a specific vdev of an ar,
>> +	 * check whether its already started, vdev which is started
>> +	 * are not allowed to switch to a new radio.
>> +	 * If the vdev is not started, but was earlier created on a
>> +	 * different ar, delete that vdev and create a new one. We don't
>> +	 * delete at the scan stop as an optimization to avoid redundant
>> +	 * delete-create vdev's for the same ar, in case the request is
>> +	 * always on the same band for the vif
>> +	 */
>> +	if (arvif->is_created) {
>> +		if (WARN_ON(!arvif->ar))
>> +			return -EINVAL;
>> +
>> +		if (ar != arvif->ar && arvif->is_started)
>> +			return -EINVAL;
> 
> I wonder if -EBUSY would be more descriptive here? I changed to that in
> the pending branch.
> 
Yeah, landing here would mean that user has already started the 
interface on a radio(ar) and now requesting RoC on a channel that 
doesn't belong to it.
>> +		if (ar != arvif->ar) {
>> +			/* backup the previously used ar ptr, since the vdev delete
>> +			 * would assign the arvif->ar to NULL after the call
>> +			 */
>> +			prev_ar = arvif->ar;
>> +			mutex_lock(&prev_ar->conf_mutex);
>> +			ret = ath12k_mac_vdev_delete(prev_ar, vif);
>> +			mutex_unlock(&prev_ar->conf_mutex);
>> +			if (ret)
>> +				ath12k_warn(prev_ar->ab,
>> +					    "unable to delete scan vdev %d\n", ret);
> 
> Do we really want to continue if vdev_delete() fails? In the pending
> branch I added 'return ret' here and modified the warning message a bit.
> 
>> +		} else {
>> +			create = false;
>> +		}
>> +	}
>> +
>> +	if (create) {
>> +		mutex_lock(&ar->conf_mutex);
>> +		ret = ath12k_mac_vdev_create(ar, vif);
>> +		mutex_unlock(&ar->conf_mutex);
>> +		if (ret) {
>> +			ath12k_warn(ar->ab, "unable to create scan vdev %d\n", ret);
>> +			return -EINVAL;
>> +		}
> 
> Also here I modified the warning message a bit.
> 
> The pending commit here:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=9b4ec32e921b34bd7a03d39cc0a75cba7e85dc02
> 
Changes looks fine for me, thanks a lot for Fixing them.