linux-kernel - Re: Question about suspend/resume clock handling in dwc3-of-simple.c

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Message-ID: <2ec1668d-9e27-926f-5cad-f9f1b541ef84@roeck-us.net>
Date:   Tue, 13 Sep 2016 06:10:52 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Felipe Balbi <balbi@...nel.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Question about suspend/resume clock handling in dwc3-of-simple.c

On 09/12/2016 10:35 PM, Felipe Balbi wrote:
>
> Hi,
>
> Guenter Roeck <linux@...ck-us.net> writes:
>>>> Should it be clk_disable_unprepare(), or maybe something like the
>>>> following
>>>>
>>>> 	if (!pm_runtime_status_suspended(dev))
>>>> 		clk_disable_unprepare();
>>>> 	else
>>>> 		clk_unprepare();
>>>
>>> I'm not sure how balanced those calls are, yeah. I don't have HW to test
>>> PM with. But note that as it is, there is no actual runtime PM support,
>>> so clk_disable_unprepare() will always be necessary.
>>>
>>> Perhaps we will find further issues when someone tries to use runtime PM
>>> with dwc3-of-simple. ;-)
>>>
>>
>> We are working on code derived from it, so unless I can convince the author
>> that he can not just use clk_unprepare() I suspect we'll hit the problem.
>> If so, I'll let you know.
>
> Are you sending that upstream? Depending on your requirements, it might
> be easier to patch dwc3-of-simple.c then adding yet another glue layer :-)
>
Yes. It will be a glue layer. So far that looks like the cleanest solution.

Thanks,
Guenter