netdev - Re: [PATCH] [net,v2] net: wwan: t7xx: add PM_AUTOSUSPEND_MS_BY

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Message-ID: <CAAQ7Y6aqLJoScfVD3NMyw_0r42qYS2BCCWa5iRDaM8h1EKwwkg@mail.gmail.com>
Date: Tue, 22 Oct 2024 11:16:44 +0800
From: 吳逼逼 <wojackbb@...il.com>
To: Andrew Lunn <andrew@...n.ch>
Cc: netdev@...r.kernel.org, chandrashekar.devegowda@...el.com, 
	chiranjeevi.rapolu@...ux.intel.com, haijun.liu@...iatek.com, 
	m.chetan.kumar@...ux.intel.com, ricardo.martinez@...ux.intel.com, 
	loic.poulain@...aro.org, ryazanov.s.a@...il.com, johannes@...solutions.net, 
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, 
	linux-arm-kernel@...ts.infradead.org, angelogioacchino.delregno@...labora.com, 
	linux-mediatek@...ts.infradead.org, matthias.bgg@...il.com
Subject: Re: [PATCH] [net,v2] net: wwan: t7xx: add PM_AUTOSUSPEND_MS_BY_DW5933E
 for Dell DW5933e

Andrew Lunn <andrew@...n.ch> 於 2024年10月15日 週二 下午8:09寫道：

>
> On Tue, Oct 15, 2024 at 10:48:15AM +0800, 吳逼逼 wrote:
> > Hi Andrew,
> >
> > We have a power test that uses a small script to loop through the power_state
> > of Dell DW5933e.(/sys/bus/pci/devices/..../power_state)
> >
> > We expect that PCIE can enter the D3 state when Host don;t have data packet
> > transmission,
> > but the experimental result of the small script test is that it is only in the
> > D3 state about 5% of the time.
> >
> > We analyze logs to found that Dell DW5933e occasionally sends signal change
> > notifications, and ModemManager occasionally captures Modem status.
> > Although these situations are not very frequent,
> > However, since the default auto suspend time is 20 seconds, the chance of PCIE
> > being able to enter the D3 state is very small.
> >
> > After we changed auto suspend to 5 seconds, PCIE have 50% of the time was in D3
> > state, which met Dell's requirements.
>
> So you answered some of my questions. But missed:
>
> What makes this machine special?
>
> It is maybe because this machine occasionally sends signal change
> notifications? There are modem status changes?
>
> Have you compared this to other machines with the same hardware? Do
> they do the same? Or is this Dell special? If it is special, why is it
> special?
>
>         Andrew

Hi Andrew,

The chip of Fibocom FM350 is MTK T7XX,
It is the same chip as our device.

We tested the Fibocom FM350 and It had the same issue as our device.
The following tests use the same environment and steps:
a. Make data call to connect Internet
b. No data is transferred to the Internet and wait one minute.
c. use test script to capture and count power_state until one minute.

Result:
1. When autosuspend_delay_ms is 20000,
Our device's d3_cold time is 0%
Fibocom FM350's d3_cold time 0%

2. When autosuspend_delay_ms is 5000,
Our device's d3_cold time is 80%
Fibocom FM350's d3_cold time 60%

So this problem is a common problem.
Should I remove PM_AUTOSUSPEND_MS_BY_DW5933E,
and modify PM_AUTOSUSPEND_MS to 5000 at my patch?

Thanks.