RE: [PATCH] rtw88: 8821c: disable the ASPM of RTL8821CE

[Pkshih]

> -----Original Message-----
> From: Jian-Hong Pan <jhp@xxxxxxxxxxxxx>
> Sent: Friday, December 10, 2021 5:34 PM
> To: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> Cc: Pkshih <pkshih@xxxxxxxxxxx>; Yan-Hsuan Chuang <tony0620emma@xxxxxxxxx>; Kalle Valo
> <kvalo@xxxxxxxxxxxxxx>; linux-wireless@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; linux@xxxxxxxxxxxxx
> Subject: Re: [PATCH] rtw88: 8821c: disable the ASPM of RTL8821CE
> 
> Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> 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@xxxxxxxxxxx> wrote:
> > >
> > > +Kai-Heng
> > >
> > > > -----Original Message-----
> > > > From: Jian-Hong Pan <jhp@xxxxxxxxxxxxx>
> > > > Sent: Friday, December 10, 2021 4:17 PM
> > > > To: Pkshih <pkshih@xxxxxxxxxxx>; Yan-Hsuan Chuang <tony0620emma@xxxxxxxxx>; Kalle Valo
> > > > <kvalo@xxxxxxxxxxxxxx>
> > > > Cc: linux-wireless@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > > > linux@xxxxxxxxxxxxx; Jian-Hong Pan <jhp@xxxxxxxxxxxxx>
> > > > 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@xxxxxxxxxxxxx>
> > >
> > > 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.

> 
> > > 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