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Subject: Re: [PATCH V2 3/6] brcmfmac: reserve 2 credits for host tx control
 path
To:     Chi-Hsien Lin <chi-hsien.lin@cypress.com>,
        Kalle Valo <kvalo@codeaurora.org>
Cc:     linux-wireless@vger.kernel.org, brcm80211-dev-list@broadcom.com,
        brcm80211-dev-list@cypress.com,
        Arend van Spriel <arend.vanspriel@broadcom.com>,
        Franky Lin <franky.lin@broadcom.com>,
        Hante Meuleman <hante.meuleman@broadcom.com>,
        Wright Feng <wright.feng@cypress.com>,
        Amar Shankar <amsr@cypress.com>,
        Jia-Shyr Chuang <joseph.chuang@cypress.com>
References: <20200610152106.175257-1-chi-hsien.lin@cypress.com>
 <20200610152106.175257-4-chi-hsien.lin@cypress.com>
 <f0910f96-1d23-daf1-b517-363e59bff105@gmail.com>
 <875z9yr7lg.fsf@codeaurora.org>
 <ffcf55cc-b27d-78ec-ff4f-e7efa3087712@gmail.com>
 <87a6zapbqp.fsf@codeaurora.org>
 <0923f45f-03e3-a870-3d2a-35f982482e1a@cypress.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <bed18d45-6119-53da-2b9c-d98d121c8298@gmail.com>
Date:   Wed, 5 Aug 2020 17:01:04 +0300
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05.08.2020 11:24, Chi-Hsien Lin пишет:
> 
> On 8/5/2020 1:22 AM, Kalle Valo wrote:
>> Dmitry Osipenko <digetx@gmail.com> writes:
>>
>>> 04.08.2020 14:08, Kalle Valo пишет:
>>>> Dmitry Osipenko <digetx@gmail.com> writes:
>>>>
>>>>> 10.06.2020 18:21, Chi-Hsien Lin пишет:
>>>>>> From: Amar Shankar <amsr@cypress.com>
>>>>>>
>>>>>> It is observed that sometimes when sdiod is low in tx credits in low
>>>>>> rssi scenarios, the data path consumes all sdiod rx all credits and
>>>>>> there is no sdiod rx credit available for control path causing host
>>>>>> and card to go out of sync resulting in link loss between host and
>>>>>> card. So in order to prevent it some credits are reserved for control
>>>>>> path.
>>>>>>
>>>>>> Note that TXCTL_CREDITS can't be larger than the firmware default
>>>>>> credit update threshold 2; otherwise there will be a deadlock for
>>>>>> both
>>>>>> side waiting for each other.
>>>>>>
>>>>>> Signed-off-by: Amar Shankar <amsr@cypress.com>
>>>>>> Signed-off-by: Jia-Shyr Chuang <joseph.chuang@cypress.com>
>>>>>> Signed-off-by: Chi-Hsien Lin <chi-hsien.lin@cypress.com>
>>>> [...]
>>>>
>>>>> This patch causes a severe WiFi performance regression on BCM4329.
>>>>> Please fix or revert this patch, thanks in advance.
>>>>>
>>>>> Before this patch:
>>>>> - - - - - - - - - - - - - - - - - - - - - - - - -
>>>>> [ ID] Interval           Transfer     Bitrate         Retr
>>>>> [  5]   0.00-10.00  sec  17.2 MBytes  14.4 Mbits/sec   
>>>>> 0             sender
>>>>> [  5]   0.00-10.04  sec  16.9 MBytes  14.1 Mbits/sec
>>>>> receiver
>>>>>
>>>>>
>>>>> After this patch:
>>>>> - - - - - - - - - - - - - - - - - - - - - - - - -
>>>>> [ ID] Interval           Transfer     Bitrate         Retr
>>>>> [  5]   0.00-10.00  sec  1.05 MBytes   881 Kbits/sec   
>>>>> 3             sender
>>>>> [  5]   0.00-14.01  sec   959 KBytes   561 Kbits/sec
>>>>> receiver
>>>> Can someone please send a revert patch (with the explanation above)
>>>> if a
>>>> fix is not quickly found? The commit id is:
>>>>
>>>> commit b41c232d33666191a1db11befc0f040fcbe664e9
>>>> Author:     Amar Shankar <amsr@cypress.com>
>>>> AuthorDate: Wed Jun 10 10:21:03 2020 -0500
>>>> Commit:     Kalle Valo <kvalo@codeaurora.org>
>>>> CommitDate: Tue Jul 14 12:46:43 2020 +0300
>>>>
>>>>      brcmfmac: reserve 2 credits for host tx control path
>>>>
>>> Hello Kalle,
>>>
>>> I'll send the revert if nobody will stand up to address the problem in a
>>> two weeks, thanks.
>> Thanks. Then I should be able to get the revert to v5.9 so that the
>> release won't be broken. (v5.8 is unaffected)
> 
> Dmitry/Kalle,
> 
> We'll take a look and revert/fix it in a few days.

Good to know, thank you.