linux-kernel - Re: [PATCH] usb: xhci-mtk: fixup mouse wakeup failure during system suspend

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Date:	Wed, 4 May 2016 09:21:13 +0800
From:	chunfeng yun <chunfeng.yun@...iatek.com>
To:	Felipe Balbi <felipe.balbi@...ux.intel.com>
CC:	Mathias Nyman <mathias.nyman@...el.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-usb@...r.kernel.org>, <linux-mediatek@...ts.infradead.org>,
	Daniel Kurtz <djkurtz@...omium.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] usb: xhci-mtk: fixup mouse wakeup failure during system
 suspend

On Tue, 2016-05-03 at 12:33 +0300, Felipe Balbi wrote:
> Hi,
> 
> chunfeng yun <chunfeng.yun@...iatek.com> writes:
> >> chunfeng yun <chunfeng.yun@...iatek.com> writes:
> >> > On Thu, 2016-04-21 at 10:04 +0800, Chunfeng Yun wrote:
> >> >> Click mouse after xhci suspend completion but before system suspend
> >> >> completion, system will not be waken up by mouse if the duration of
> >> >> them is larger than 20ms which is the device UFP's resume signaling
> >> 
> >> what is "them" here ? The duration of what is longer than 20ms ?
> > They are "xhci suspend completion" and "system suspend completion";
> >
> > It's time duration
> 
> okay. So if xhci suspend takes longer than 20ms your SPM doesn't see a
> wakeup ?
It is not the time of xhci suspend consumed, but is the time of duration
from xhci suspend completion to system suspend completion(after BOOT-CPU
is turned off, SPM will be enabled to receive wakeup event)

> 
> >> >> lasted. Another reason is that the SPM is not enabled before system
> >> 
> >> what's SPM ?
> > It is System Power Management which is powered off when system is
> > running in normal mode, and is powered on when system enters suspend
> > mode. It is used to wakeup system when some wakeup sources, such as
> > bluetooth or powerkey etc, tigger wakeup event.
> 
> okay, thanks
> 
> >> >> suspend compeltion, this causes SPM also not notice the resume signal.
> >>            ^^^^^^^^^^
> >>            completion
> >> 
> >> >> So in order to reduce the duration less than 20ms, make use of
> >> >> syscore's suspend/resume interface.
> >> 
> >> no, this is the wrong approach
> > But it seems only one workable approach from software side
> 
> I wouldn't say that. It seems to me SPM should be enabled earlier.
Yes, but normally SPM should be enabled after all CPUS are turned off,
so it's difficult to do that, I mean enable SPM before turning off CPUS
> 
> >> >> Because the syscore runs on irq disabled context, and xhci's
> >> >> suspend/resume calls some sleeping functions, enable local irq
> >> >> and then disable it during suspend/resume. This may be not a problem,
> >> >> since only boot CPU is runing.
> >> 
> >> another problem :) calling local_irq_{enable,disable}() is an indication
> >> that something's wrong.
> > Oh!
> >
> > BTW: There will be warning logs if they are not called.
> 
> yeah, I got that :-) But it's still wrong to use
> local_irq_{enable,disable}() the way you're using them :-)
Yes

Thank you very much.
>