netdev - RE: [PATCH V2 0/4] can: flexcan: fixes for stop mode

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Date:   Wed, 27 Nov 2019 09:36:39 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     Sean Nyekjaer <sean@...nix.com>,
        "mkl@...gutronix.de" <mkl@...gutronix.de>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
CC:     dl-linux-imx <linux-imx@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH V2 0/4] can: flexcan: fixes for stop mode


> -----Original Message-----
> From: Sean Nyekjaer <sean@...nix.com>
> Sent: 2019年11月27日 16:13
> To: Joakim Zhang <qiangqing.zhang@....com>; mkl@...gutronix.de;
> linux-can@...r.kernel.org
> Cc: dl-linux-imx <linux-imx@....com>; netdev@...r.kernel.org
> Subject: Re: [PATCH V2 0/4] can: flexcan: fixes for stop mode
> 
> 
> 
> On 27/11/2019 07.12, Sean Nyekjaer wrote:
> >
> >
> > On 27/11/2019 06.56, Joakim Zhang wrote:
> >>     Could you help check the patch set? With your suggestions, I have
> >> cooked a patch to exit stop mode during probe stage.
> >>
> >>     IMHO, I think this patch is unneed, now in flexcan driver, enter
> >> stop mode when suspend, and then exit stop mode when resume.
> >> AFAIK, as long as flexcan_suspend has been called, flexcan_resume
> >> will be called, unless the system hang during suspend/resume. If so,
> >> only code reset can activate OS again. Could you please tell me how
> >> does CAN stucked in stop mode at your side?
> >
> > Hi Joakim,
> >
> > Thanks I'll test this :-)
> > Guess I will have do some hacking to get it stuck in stop mode.
> >
> > We have a lot of devices in the field that doesn't have:
> > "can: flexcan: fix deadlock when using self wakeup"
> >
> > And they have traffic on both CAN interfaces, that way it's quite easy
> > to get them stuck in stop mode.
> >
> > /Sean
> 
> Hi Joakim,
> 
> I have been testing this.
> I have a hacked version of the driver that calls
> flexcan_enter_stop_mode() as the last step in the probe function.
> 
> First insert of flexcan.ko when stop mode is activated:
> flexcan 2090000.flexcan: Linked as a consumer to regulator.4
> 
> flexcan 2090000.flexcan: registering netdev failed
> 
> flexcan 2090000.flexcan: Dropping the link to regulator.4
> 
> flexcan: probe of 2090000.flexcan failed with error -110
> 
> flexcan 2094000.flexcan: Linked as a consumer to regulator.4
> 
> flexcan 2094000.flexcan: registering netdev failed
> 
> flexcan 2094000.flexcan: Dropping the link to regulator.4
> 
> flexcan: probe of 2094000.flexcan failed with error -110
> 
> 
> When I insert a flexcan.ko with the patch
> "can: flexcan: try to exit stop mode during probe stage":
> flexcan 2090000.flexcan: Linked as a consumer to regulator.4
> 
> flexcan 2090000.flexcan: Unbalanced pm_runtime_enable!
> 
> flexcan 2094000.flexcan: Linked as a consumer to regulator.4
> 
> flexcan 2094000.flexcan: Unbalanced pm_runtime_enable!
> 
> I works as I expected but, I think we need to do some pm_runtime cleanup
> when bailing with error -110.
> Anyways it works great, thanks for your work on this.

Hi Sean,

Thanks for your quirk test, I used unbind/bind to test, do not meet such issue.
I will build as a module to have a test.

Best Regards,
Joakim Zhang
> /Sean