Re: [PATCH V2 3/6] brcmfmac: reserve 2 credits for host tx control path

[Chi-Hsien Lin <chi-hsien.lin@cypress.com>]

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.