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

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Date:   Wed, 27 Nov 2019 09:12:38 +0100
From:   Sean Nyekjaer <sean@...nix.com>
To:     Joakim Zhang <qiangqing.zhang@....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



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.

/Sean