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Message-ID: <7ac45dd4-8314-d81d-72d9-a6e71fd390f7@gmail.com>
Date:   Fri, 25 Nov 2022 20:33:21 +0200
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Subject: Re: [PATCH 1/2] wifi: rtl8xxxu: Fix the channel width reporting
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To:     Ping-Ke Shih <pkshih@realtek.com>,
        "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Cc:     Jes Sorensen <Jes.Sorensen@gmail.com>
References: <00489244-ba7c-797a-28f0-8788a40f7974@gmail.com>
 <5992feea33944726b62d63951f118e7e@realtek.com>
 <9837ba7eda3b4bec83e1630591bfc956@realtek.com>
From:   Bitterblue Smith <rtl8821cerfe2@gmail.com>
In-Reply-To: <9837ba7eda3b4bec83e1630591bfc956@realtek.com>
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On 25/11/2022 10:16, Ping-Ke Shih wrote:
> 
>> -----Original Message-----
>> From: Ping-Ke Shih <pkshih@realtek.com>
>> Sent: Friday, November 25, 2022 4:05 PM
>> To: Bitterblue Smith <rtl8821cerfe2@gmail.com>; linux-wireless@vger.kernel.org
>> Cc: Jes Sorensen <Jes.Sorensen@gmail.com>
>> Subject: RE: [PATCH 1/2] wifi: rtl8xxxu: Fix the channel width reporting
>>
>>
>>
>>> -----Original Message-----
>>> From: Bitterblue Smith <rtl8821cerfe2@gmail.com>
>>> Sent: Thursday, November 24, 2022 5:31 AM
>>> To: linux-wireless@vger.kernel.org
>>> Cc: Jes Sorensen <Jes.Sorensen@gmail.com>; Ping-Ke Shih <pkshih@realtek.com>
>>> Subject: [PATCH 1/2] wifi: rtl8xxxu: Fix the channel width reporting
>>>
>>> The gen 2 chips RTL8192EU and RTL8188FU periodically send the driver
>>> reports about the TX rate, and the driver passes these reports to
>>> sta_statistics. The reports from RTL8192EU may or may not include the
>>> channel width. The reports from RTL8188FU do not include it.
>>>
>>> Only access the c2h->ra_report.bw field if the report (skb) is big
>>> enough.
>>>
>>> The other problem fixed here is that the code was actually never
>>> changing the channel width initially reported by
>>> rtl8xxxu_bss_info_changed because the value of RATE_INFO_BW_20 is 0.
>>>
>>> Fixes: 0985d3a410ac ("rtl8xxxu: Feed current txrate information for mac80211")
>>> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
>>> ---
>>>  drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c | 10 +++++++---
>>>  1 file changed, 7 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
>>> b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
>>> index 28f136064297..1c29d0bf09e2 100644
>>> --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
>>> +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
>>> @@ -5569,7 +5569,6 @@ static void rtl8xxxu_c2hcmd_callback(struct work_struct *work)
>>>  			rarpt->txrate.flags = 0;
>>>  			rate = c2h->ra_report.rate;
>>>  			sgi = c2h->ra_report.sgi;
> 
> Additional one question about small size of report (skb).
> Is it possible you can't access .sgi and .rate too?
> 
I don't think so, because they are in the first byte of the payload.
The payload would have to be 0 bytes long, which is not very useful.
Also, the RTL8192EU and RTL8188FU drivers access the first byte
unconditionally.

>>> -			bw = c2h->ra_report.bw;
>>>
>>>  			if (rate < DESC_RATE_MCS0) {
>>>  				rarpt->txrate.legacy =
>>> @@ -5586,8 +5585,13 @@ static void rtl8xxxu_c2hcmd_callback(struct work_struct *work)
>>>  						RATE_INFO_FLAGS_SHORT_GI;
>>>  				}
>>>
>>> -				if (bw == RATE_INFO_BW_20)
>>> -					rarpt->txrate.bw |= RATE_INFO_BW_20;
>>> +				if (skb->len >= 2 + 7) {
>>
>> I think 2 is header length of C2H, and 7 is sizeof(c2h->ra_report), so we can
>> have:
>> #define RTL8XXXU_C2H_HDR_LEN 2
>>
>> Then, replace this statement with
>>
>> if (skb->len >= RTL8XXXU_C2H_HDR_LEN + sizeof(c2h->ra_report))

That sounds good.

>>
>> By the way, I found 'struct rtl8723bu_c2h' miss '__packed'.
>>

I will add it.

>> --
>> Ping-Ke
>>
>>
>> ------Please consider the environment before printing this e-mail.