netdev - Re: [PATCH V2 2/4] can: flexcan: try to exit stop mode during probe stage

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Date:   Thu, 5 Dec 2019 12:32:27 +0100
From:   Sean Nyekjaer <sean@...nix.com>
To:     Joakim Zhang <qiangqing.zhang@....com>,
        Marc Kleine-Budde <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 2/4] can: flexcan: try to exit stop mode during probe
 stage



On 05/12/2019 12.19, Joakim Zhang wrote:
> 
>> -----Original Message-----
>> From: Sean Nyekjaer <sean@...nix.com>
>> Sent: 2019年12月5日 19:12
>> To: Joakim Zhang <qiangqing.zhang@....com>; Marc Kleine-Budde
>> <mkl@...gutronix.de>; linux-can@...r.kernel.org
>> Cc: dl-linux-imx <linux-imx@....com>; netdev@...r.kernel.org
>> Subject: Re: [PATCH V2 2/4] can: flexcan: try to exit stop mode during probe
>> stage
>>
>>
>>
>> On 05/12/2019 12.04, Joakim Zhang wrote:
>>> Hi Sean,
>>>
>>> At my side, both Power-On-Reset and reboot from console can get CAN-IP out
>> of stop mode, HW is i.MX7D-SDB/i.MX8QXP-mek.
>>> I think HW design could make difference.
>>>
>>> We more care about how does CAN-IP stuck in stop mode, could you please
>> explain in details? We want figure out the root cause.
>>
>> When running only with the first stop mode commit:
>> de3578c198c6 ("can: flexcan: add self wakeup support") And there is incoming
>> traffic on both CAN lines.
>> I happens when going into suspend.
>> Then the CAN-IP is stuck in stop mode..
> 
> That means with below patch then CAN-IP could not been stuck in stop mode, right?
> 	can: flexcan: fix deadlock when using self wakeup
Yes :)
> 
> If yes, I think we don't need check stop mode in probe stage, since issue has disappeared automatically.

If one have devices deployed where:
"can: flexcan: fix deadlock when using self wakeup" isn't applied.
They could have devices stuck in stop-mode.

That's what i meant by this patch doesn't do any harm to have the check 
included.

/Sean