linux-kernel - Re: [PATCH 3/4] usb: dwc3: exynos: Enable runtime power management

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Date:	Mon, 28 Jan 2013 17:57:04 +0530
From:	Vivek Gautam <gautamvivek1987@...il.com>
To:	balbi@...com
Cc:	Vivek Gautam <gautam.vivek@...sung.com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org, gregkh@...uxfoundation.org,
	sarah.a.sharp@...ux.intel.com, kgene.kim@...sung.com,
	dianders@...omium.org, sylvester.nawrocki@...il.com,
	tomasz.figa@...il.com
Subject: Re: [PATCH 3/4] usb: dwc3: exynos: Enable runtime power management

On Mon, Jan 28, 2013 at 5:42 PM, Felipe Balbi <balbi@...com> wrote:
> Hi,
>
> On Mon, Jan 28, 2013 at 05:28:30PM +0530, Vivek Gautam wrote:
>> >> +static int dwc3_exynos_runtime_resume(struct device *dev)
>> >> +{
>> >> +     struct dwc3_exynos      *exynos = dev_get_drvdata(dev);
>> >> +     struct platform_device  *pdev_dwc = exynos->dwc3;
>> >> +     struct dwc3             *dwc = NULL;
>> >> +
>> >> +     dwc = platform_get_drvdata(pdev_dwc);
>> >> +
>> >> +     clk_enable(exynos->clk);
>> >> +
>> >> +     if (!dwc)
>> >> +             return 0;
>> >> +
>> >> +     pm_runtime_get_sync(dwc->usb3_phy->dev);
>> >
>> > dude, this is wrong :-)
>> >
>> > look at this:
>> >
>> > pm_runtime_get() -> dwc3_exynos_runtime_resume() ->
>> > pm_runtime_get_sync() -> dwc3_exynos_runtime_resume() -> ...
>> >
>> > only your clock enalbe should do
>> >
>>
>> We want to wake up "dwc->usb3_phy" so tried to call pm_runtime_get_sync()
>> with "dwc->usb3_phy->dev".
>> Missing something ? :-(
>
> oh, my bad. That's the PHY... But we can't really do that for samsung
> only. It needs to be done generically for the entire dwc3 core driver,
> and for that we need to introduce usb_phy_autopm_get(),
> usb_phy_autopm_get_sync() and friends.
>

aah!! Ok. I definitely missed that part. :-(

> Then, from dwc_probe() we call:
>
> phy = usb_get_phy();
> usb_phy_autopm_enable(phy);
> usb_phy_autopm_get_sync(phy);
>
> or something similar ;-) Bottom line, you shouldn't fiddle with phy->dev
> directly.
>

Ok, the core should actually be handling the 'phy' not the glue layers.
Right ?

Will try putting these helper functions in place and come up with a
solution. :-)


-- 
Thanks & Regards
Vivek
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