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References: <20211215114635.333767-1-kai.heng.feng@canonical.com> <d2ddfaa035315ca91a2a05a8188810ff50db83c8.camel@realtek.com>
In-Reply-To: <d2ddfaa035315ca91a2a05a8188810ff50db83c8.camel@realtek.com>
From:   Jian-Hong Pan <jhp@endlessos.org>
Date:   Thu, 16 Dec 2021 10:46:16 +0800
Message-ID: <CAPpJ_ecgPDniiBWnZLfDuQSiW4rvHJ1f4++SsZ3=aTjy_B0Fjg@mail.gmail.com>
Subject: Re: [PATCH v4] rtw88: Disable PCIe ASPM while doing NAPI poll on 8821CE
To:     Pkshih <pkshih@realtek.com>
Cc:     "kai.heng.feng@canonical.com" <kai.heng.feng@canonical.com>,
        "tony0620emma@gmail.com" <tony0620emma@gmail.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "jian-hong@endlessm.com" <jian-hong@endlessm.com>,
        "kvalo@codeaurora.org" <kvalo@codeaurora.org>,
        Bernie Huang <phhuang@realtek.com>,
        "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "kuba@kernel.org" <kuba@kernel.org>,
        "briannorris@chromium.org" <briannorris@chromium.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux@endlessos.org
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Pkshih <pkshih@realtek.com> =E6=96=BC 2021=E5=B9=B412=E6=9C=8815=E6=97=A5 =
=E9=80=B1=E4=B8=89 =E4=B8=8B=E5=8D=888:23=E5=AF=AB=E9=81=93=EF=BC=9A
>
> On Wed, 2021-12-15 at 19:46 +0800, Kai-Heng Feng wrote:
> > Many Intel based platforms face system random freeze after commit
> > 9e2fd29864c5 ("rtw88: add napi support").
> >
> > The commit itself shouldn't be the culprit. My guess is that the 8821CE
> > only leaves ASPM L1 for a short period when IRQ is raised. Since IRQ is
> > masked during NAPI polling, the PCIe link stays at L1 and makes RX DMA
> > extremely slow. Eventually the RX ring becomes messed up:
> > [ 1133.194697] rtw_8821ce 0000:02:00.0: pci bus timeout, check dma stat=
us
> >
> > Since the 8821CE hardware may fail to leave ASPM L1, manually do it in
> > the driver to resolve the issue.
> >
> > Fixes: 9e2fd29864c5 ("rtw88: add napi support")
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=3D215131
> > BugLink: https://bugs.launchpad.net/bugs/1927808
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
>
> Reviewed-and-Tested-by: Ping-Ke Shih <pkshih@realtek.com>

Acked-by: Jian-Hong Pan <jhp@endlessos.org>

> > ---
> > v4:
> >  - Rebase to the right tree.
> >
> > v3:
> >  - Move the module parameter to be part of private struct.
> >  - Ensure link_usage never goes below zero.
> >
> > v2:
> >  - Add default value for module parameter.
> >
> >  drivers/net/wireless/realtek/rtw88/pci.c | 70 +++++++-----------------
> >  drivers/net/wireless/realtek/rtw88/pci.h |  2 +
> >  2 files changed, 21 insertions(+), 51 deletions(-)
> >
> >
>
> [...]
>
>