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Message-ID: <2152e5f1-cecd-f5d2-ca4b-e7ed159f40b7@quicinc.com>
Date:   Thu, 23 Mar 2023 11:41:14 +0530
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Subject: Re: [PATCH v3] wifi: ath11k: Optimize 6 GHz scan time
To:     Kalle Valo <kvalo@kernel.org>
CC:     <ath11k@lists.infradead.org>, <linux-wireless@vger.kernel.org>
References: <20230315112103.18426-1-quic_mpubbise@quicinc.com>
 <167948612507.6445.2579526780286789940.kvalo@kernel.org>
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From:   Manikanta Pubbisetty <quic_mpubbise@quicinc.com>
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On 3/22/2023 5:25 PM, Kalle Valo wrote:
> Manikanta Pubbisetty <quic_mpubbise@quicinc.com> wrote:
> 
>> Currently, time taken to scan all supported channels on WCN6750
>> is ~8 seconds and connection time is almost 10 seconds. WCN6750
>> supports three Wi-Fi bands (i.e., 2.4/5/6 GHz) and the numbers of
>> channels for scan come around ~100 channels (default case).
>> Since the chip doesn't have support for DBS (Dual Band Simultaneous),
>> scans cannot be parallelized resulting in longer scan times.
>>
>> Among the 100 odd channels, ~60 channels are in 6 GHz band. Therefore,
>> optimizing the scan for 6 GHz channels will bring down the overall
>> scan time.
>>
>> WCN6750 firmware has support to scan a 6 GHz channel based on co-located
>> AP information i.e., RNR IE which is found in the legacy 2.4/5 GHz scan
>> results. When a scan request with all supported channel list is enqueued
>> to the firmware, then based on WMI_SCAN_CHAN_FLAG_SCAN_ONLY_IF_RNR_FOUND
>> scan channel flag, firmware will scan only those 6 GHz channels for which
>> RNR IEs are found in the legacy scan results.
>>
>> In the proposed design, based on NL80211_SCAN_FLAG_COLOCATED_6GHZ scan
>> flag, driver will set the WMI_SCAN_CHAN_FLAG_SCAN_ONLY_IF_RNR_FOUND flag
>> for non-PSC channels. Since there is high probability to find 6 GHz APs
>> on PSC channels, these channels are always scanned. Only non-PSC channels
>> are selectively scanned based on cached RNR information from the legacy
>> scan results.
>>
>> If NL80211_SCAN_FLAG_COLOCATED_6GHZ is not set in the scan flags,
>> then scan will happen on all supported channels (default behavior).
>>
>> With these optimizations, scan time is improved by 1.5-1.8 seconds on
>> WCN6750. Similar savings have been observed on WCN6855.
>>
>> Tested-on: WCN6750 hw1.0 AHB WLAN.MSL.1.0.1-00887-QCAMSLSWPLZ-1
>> Tested-on: WCN6855 hw2.1 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.16
>>
>> Signed-off-by: Manikanta Pubbisetty <quic_mpubbise@quicinc.com>
>> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
> 
> New warning:
> 
> drivers/net/wireless/ath/ath11k/mac.c:3827: line length of 91 exceeds 90 columns
> 
> I couldn't quickly figure out how to fix that, any ideas?
> 

I'd thought that max_line_length is 100 from the checkpatch.pl; I have 
sent V4 patch addressing the warning.

Thanks,
Manikanta