linux-kernel - Re: [PATCH v6 01/11] drivers: usb: otg: add a new driver for omap usb2 phy

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Date:	Mon, 6 Aug 2012 15:14:42 +0530
From:	"ABRAHAM, KISHON VIJAY" <kishon@...com>
To:	balbi@...com
Cc:	grant.likely@...retlab.ca, rob.herring@...xeda.com,
	rob@...dley.net, linux@....linux.org.uk,
	gregkh@...uxfoundation.org, b-cousson@...com, rnayak@...com,
	tony@...mide.com, devicetree-discuss@...ts.ozlabs.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
	linux-usb@...r.kernel.org
Subject: Re: [PATCH v6 01/11] drivers: usb: otg: add a new driver for omap
 usb2 phy

Hi Felipe,

On Mon, Aug 6, 2012 at 2:19 PM, Felipe Balbi <balbi@...com> wrote:
> Hi,
>
> On Fri, Aug 03, 2012 at 08:01:44PM +0530, ABRAHAM, KISHON VIJAY wrote:
>> >> +     return 0;
>> >> +}
>> >> +
>> >> +#ifdef CONFIG_PM_RUNTIME
>> >> +
>> >> +static int omap_usb2_runtime_suspend(struct device *dev)
>> >> +{
>> >> +     struct platform_device  *pdev = to_platform_device(dev);
>> >> +     struct omap_usb *phy = platform_get_drvdata(pdev);
>> >> +
>> >> +     clk_disable(phy->wkupclk);
>> >
>> > weird. I would expect the wakeup clock to be enabled on suspend and
>> > disabled on resume. Isn't this causing any unbalanced disable warnings ?
>>
>> Even I was expecting the wakeup clock to be enabled on suspend but if
>> we have this enabled coreaon domain is never
>> gated and core does not hit low power state. btw Why do think this is
>> unbalanced?
>
> because you never do a clk_enable() on probe(), so on your first
> suspend, you will disable the clock without having enabled it before,
> no? Unless pm_runtime forces a runtime_resume() when you call
> pm_runtime_enable()...
>
>> >> +static int omap_usb2_runtime_resume(struct device *dev)
>> >> +{
>> >> +     u32 ret = 0;
>> >> +     struct platform_device  *pdev = to_platform_device(dev);
>> >> +     struct omap_usb *phy = platform_get_drvdata(pdev);
>> >> +
>> >> +     ret = clk_enable(phy->wkupclk);
>> >> +     if (ret < 0)
>> >> +             dev_err(phy->dev, "Failed to enable wkupclk %d\n", ret);
>> >> +
>> >> +     return ret;
>> >> +}
>> >> +
>> >> +static const struct dev_pm_ops omap_usb2_pm_ops = {
>> >> +     SET_RUNTIME_PM_OPS(omap_usb2_runtime_suspend, omap_usb2_runtime_resume,
>> >> +             NULL)
>> >
>> > only runtime ? What about static suspend ? We need this to work also
>> > after a traditional echo mem > /sys/power/state ;-)
>>
>> The static suspend case is handled by users of this phy using
>> set_suspend hooks.
>
> I'm not sure if that's too wise, what if your user enabled USB, but
> for whatever reason loaded only the phy driver and not musb or dwc3. It
> will fail, right ?

The enabling and disabling of phy is solely governed by usb controller
driver (musb/dwc3). So if you dont have musb/dwc3 loaded, the phy will
be for sure disabled.

Thanks
Kishon
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