netdev - Re: [PATCH] rtw88: 8821c: disable the ASPM of RTL8821CE

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Date:   Mon, 13 Dec 2021 15:30:56 +0800
From:   Jian-Hong Pan <jhp@...lessos.org>
To:     Pkshih <pkshih@...ltek.com>
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Yan-Hsuan Chuang <tony0620emma@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux@...lessos.org" <linux@...lessos.org>
Subject: Re: [PATCH] rtw88: 8821c: disable the ASPM of RTL8821CE

Pkshih <pkshih@...ltek.com> 於 2021年12月11日 週六 下午2:31寫道：
>
>
> > -----Original Message-----
> > From: Jian-Hong Pan <jhp@...lessos.org>
> > Sent: Friday, December 10, 2021 5:34 PM
> > To: Kai-Heng Feng <kai.heng.feng@...onical.com>
> > Cc: Pkshih <pkshih@...ltek.com>; Yan-Hsuan Chuang <tony0620emma@...il.com>; Kalle Valo
> > <kvalo@...eaurora.org>; linux-wireless@...r.kernel.org; netdev@...r.kernel.org;
> > linux-kernel@...r.kernel.org; linux@...lessos.org
> > Subject: Re: [PATCH] rtw88: 8821c: disable the ASPM of RTL8821CE
> >
> > Kai-Heng Feng <kai.heng.feng@...onical.com> 於 2021年12月10日 週五 下午5:24寫道：
> > >
> > > On Fri, Dec 10, 2021 at 5:00 PM Pkshih <pkshih@...ltek.com> wrote:
> > > >
> > > > +Kai-Heng
> > > >
> > > > > -----Original Message-----
> > > > > From: Jian-Hong Pan <jhp@...lessos.org>
> > > > > Sent: Friday, December 10, 2021 4:17 PM
> > > > > To: Pkshih <pkshih@...ltek.com>; Yan-Hsuan Chuang <tony0620emma@...il.com>; Kalle Valo
> > > > > <kvalo@...eaurora.org>
> > > > > Cc: linux-wireless@...r.kernel.org; netdev@...r.kernel.org; linux-kernel@...r.kernel.org;
> > > > > linux@...lessos.org; Jian-Hong Pan <jhp@...lessos.org>
> > > > > Subject: [PATCH] rtw88: 8821c: disable the ASPM of RTL8821CE
> > > > >
> > > > > More and more laptops become frozen, due to the equipped RTL8821CE.
> > > > >
> > > > > This patch follows the idea mentioned in commits 956c6d4f20c5 ("rtw88:
> > > > > add quirks to disable pci capabilities") and 1d4dcaf3db9bd ("rtw88: add
> > > > > quirk to disable pci caps on HP Pavilion 14-ce0xxx"), but disables its
> > > > > PCI ASPM capability of RTL8821CE directly, instead of checking DMI.
> > > > >
> > > > > Buglink:https://bugzilla.kernel.org/show_bug.cgi?id=215239
> > > > > Fixes: 1d4dcaf3db9bd ("rtw88: add quirk to disable pci caps on HP Pavilion 14-ce0xxx")
> > > > > Signed-off-by: Jian-Hong Pan <jhp@...lessos.org>
> > > >
> > > > We also discuss similar thing in this thread:
> > > > https://bugzilla.kernel.org/show_bug.cgi?id=215131
> > > >
> > > > Since we still want to turn on ASPM to save more power, I would like to
> > > > enumerate the blacklist. Does it work to you?
> > >
> > > Too many platforms are affected, the blacklist method won't scale.
> >
> > Exactly!
>
> Got it.
>
> >
> > > Right now it seems like only Intel platforms are affected, so can I
> > > propose a patch to disable ASPM when its upstream port is Intel?
> >
> > I only have laptops with Intel chip now.  So, I am not sure the status
> > with AMD platforms.
> > If this is true, then "disable ASPM when its upstream port is Intel"
> > might be a good idea.
> >
>
> Jian-Hong, could you try Kai-Heng's workaround that only turn off ASPM
> during NAPI poll function. If it also works to you, I think it is okay
> to apply this workaround to all Intel platform with RTL8821CE chipset.
> Because this workaround has little (almost no) impact of power consumption.

According to Kai-Heng's hack patch [1] and the comment [2] mentioning
checking "ref_cnt" by rtw_pci_link_ps(), I arrange the patch as
following.
This patch only disables ASPM (if the hardware has the capability)
when system gets into rtw_pci_napi_poll() and re-enables ASPM when it
leaves rtw_pci_napi_poll().  It is as Ping-Ke mentioned "only turn off
ASPM during NAPI poll function".
The WiFi & BT work, and system is still alive after I use the internet
awhile.  Besides, there is no more "pci bus timeout, check dma status"
error.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=215131#c11
[2] https://bugzilla.kernel.org/show_bug.cgi?id=215131#c15

Jian-Hong Pan

diff --git a/drivers/net/wireless/realtek/rtw88/pci.c
b/drivers/net/wireless/realtek/rtw88/pci.c
index a7a6ebfaa203..a6fdddecd37d 100644
--- a/drivers/net/wireless/realtek/rtw88/pci.c
+++ b/drivers/net/wireless/realtek/rtw88/pci.c
@@ -1658,6 +1658,7 @@ static int rtw_pci_napi_poll(struct napi_struct
*napi, int budget)
                                              priv);
        int work_done = 0;

+       rtw_pci_link_ps(rtwdev, false);
        while (work_done < budget) {
                u32 work_done_once;

@@ -1681,6 +1682,7 @@ static int rtw_pci_napi_poll(struct napi_struct
*napi, int budget)
                if (rtw_pci_get_hw_rx_ring_nr(rtwdev, rtwpci))
                        napi_schedule(napi);
        }
+       rtw_pci_link_ps(rtwdev, true);

        return work_done;
 }

> >
> > > > If so, please help to add one quirk entry of your platform.
> > > >
> > > > Another thing is that "attachment 299735" is another workaround for certain
> > > > platform. And, we plan to add quirk to enable this workaround.
> > > > Could you try if it works to you?
> > >
> > > When the hardware is doing DMA, it should initiate leaving ASPM L1,
> > > correct? So in theory my workaround should be benign enough for most
> > > platforms.
>
> I don't see and know the detail of hardware waveform, but I think your
> understanding is correct.
>
> --
> Ping-Ke
>