Hi Felipe,
On Mon, Sep 12, 2016 at 10:05:00PM +0300, Felipe Balbi wrote:
>
> Hi Guenter,
>
> Guenter Roeck <linux@xxxxxxxxxxxx> writes:
> > Hi folks,
> >
> > In dwc3-of-simple.c:dwc3_of_simple_remove(), I see the following code.
> >
> > for (i = 0; i < simple->num_clocks; i++) {
> > clk_unprepare(simple->clks[i]);
> > clk_put(simple->clks[i]);
> > }
> >
> > What I don't understand is why clk_unprepare() is called instead
> > of clk_disable_unprepare(). Someone told me that it was due to
> > dwc3_of_simple_runtime_suspend(), which would call clk_disable().
>
> good eyes :-) That was fixed though:
>
> https://marc.info/?l=linux-usb&m=147343692631868&w=2
>
Great, thanks!
> > 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.
Thanks!
Guenter
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