Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org AE364C433C9
From:   Kalle Valo <kvalo@codeaurora.org>
To:     Dmitry Osipenko <digetx@gmail.com>
Cc:     Chi-Hsien Lin <chi-hsien.lin@cypress.com>,
        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>
Subject: Re: [PATCH V2 3/6] brcmfmac: reserve 2 credits for host tx control path
References: <20200610152106.175257-1-chi-hsien.lin@cypress.com>
        <20200610152106.175257-4-chi-hsien.lin@cypress.com>
        <f0910f96-1d23-daf1-b517-363e59bff105@gmail.com>
Date:   Tue, 04 Aug 2020 14:08:59 +0300
In-Reply-To: <f0910f96-1d23-daf1-b517-363e59bff105@gmail.com> (Dmitry
        Osipenko's message of "Mon, 3 Aug 2020 19:27:41 +0300")
Message-ID: <875z9yr7lg.fsf@codeaurora.org>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

Dmitry Osipenko <digetx@gmail.com> writes:

> 10.06.2020 18:21, Chi-Hsien Lin =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
>> From: Amar Shankar <amsr@cypress.com>
>>=20
>> 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.
>>=20
>> 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.
>>=20
>> 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             sen=
der
> [  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             sen=
der
> [  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

--=20
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatc=
hes