Subject: Re: [PATCH v2] can: Fix bug in suspend/resume

From: Marc Kleine-Budde <[email-masked]>
Date: Fri, 14 Nov 2014 16:09:35 +0100

On 11/14/2014 04:05 PM, Sören Brinkmann wrote:
> On Fri, 2014-11-14 at 09:54AM +0100, Marc Kleine-Budde wrote:
>> On 11/14/2014 09:16 AM, Kedareswara rao Appana wrote:
>>> The drvdata in the suspend/resume is of type struct net_device,
>>> not the platform device.Enable the clocks in the suspend before
>>> accessing the registers of the CAN.
>>>
>>> Signed-off-by: Kedareswara rao Appana <[email-masked]>
>>> ---
>>> Changes for v2:
>>>   - Removed the struct platform_device* from suspend/resume
>>>     as suggest by Lothar.
>>>   - The clocks are getting disabled and un prepared at the end of the probe. 
>>>     In the suspend the driver is doing a register write.In order
>>>     To do that register write we have to again enable and prepare the clocks.
>>
>> Please look the at suspend/resume code and count the
>> clock_enable/disable manually. After a suspend/resume cycle, you have
>> enabled the clock twice, but disabled it once.
>>
>> I think you have to abstract the clock handling behind runtime PM. I
>> haven't done this myself yet, but the strong feeling that this is a
>> possible solution to your problem. These links might help:
> 
> I agree, the clock handling looks weird. Also the clk_disable calls in
> xcan_get_berr_counter() look suspicious to me, but I might be wrong.
> I think you can take a look at gpio-zynq for an example for runtime_pm
> usage. I think the usage model in that driver is similar to here.

The xcan_get_berr_counter() function is correct, when doing manual (i.e.
non runtime-pm) clock handling. This function might be called if the
interface is down, this means clocks are disabled.

Marc

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