linux-kernel - RE: [PATCH 4/4] mfd: global Suspend and resume support of ehci and ohci

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Message-ID: <2f837bd4c0fb09f310feb414479f3350@mail.gmail.com>
Date:	Wed, 29 Jun 2011 23:47:50 +0530
From:	Partha Basak <p-basak2@...com>
To:	Alan Stern <stern@...land.harvard.edu>,
	Keshava Munegowda <keshava_mgowda@...com>
Cc:	Kevin Hilman <khilman@...com>, linux-usb@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
	Felipe Balbi <balbi@...com>, Anand Gadiyar <gadiyar@...com>,
	sameo@...ux.intel.com, parthab@...ia.ti.com, tony@...mide.com,
	Benoit Cousson <b-cousson@...com>, paul@...an.com
Subject: RE: [PATCH 4/4] mfd: global Suspend and resume support of ehci and ohci

>-----Original Message-----
>From: Alan Stern [mailto:stern@...land.harvard.edu]
>Sent: Wednesday, June 29, 2011 11:03 PM
>To: Munegowda, Keshava
>Cc: Kevin Hilman; linux-usb@...r.kernel.org; linux-omap@...r.kernel.org;
>linux-kernel@...r.kernel.org; balbi@...com; gadiyar@...com;
>sameo@...ux.intel.com; parthab@...ia.ti.com; tony@...mide.com; b-
>cousson@...com; paul@...an.com
>Subject: Re: [PATCH 4/4] mfd: global Suspend and resume support of ehci
>and ohci
>
>On Wed, 29 Jun 2011, Munegowda, Keshava wrote:
>
>> for usb host case , I am seeing that the pm_runtime_get_sync
>>
>>
>> static int rpm_resume(struct device *dev, int rpmflags)
>> {
>>   ............
>>  ..........
>> 	if (dev->pwr_domain) {
>> 		callback = dev->pwr_domain->ops.runtime_resume;
>> 		if(!strcmp(dev_name(dev),"usbhs_omap"))
>> 			 pr_err("dev->pwr_domain->ops.runtime_resume");
>> 	}
>> 	else if (dev->type && dev->type->pm) {
>> 		callback = dev->type->pm->runtime_resume;
>> 		if(!strcmp(dev_name(dev),"usbhs_omap"))
>> 			 pr_err("dev->type->pm->runtime_resume");
>> 	}
>> 	else if (dev->class && dev->class->pm) {
>> 		callback = dev->class->pm->runtime_resume;
>> 		if(!strcmp(dev_name(dev),"usbhs_omap"))
>> 			 pr_err("ev->class->pm->runtime_resume");
>> 	}
>> 	else if (dev->bus && dev->bus->pm) {
>> 		callback = dev->bus->pm->runtime_resume;
>> 	if(!strcmp(dev_name(dev),"usbhs_omap"))
>> 		 pr_err("dev->bus->pm->runtime_resume");
>> 	}
>> 	else
>> 		callback = NULL;
>> }
>>
>>
>> I am seeing that below if statement was hitting true:
>>
>> 	if (dev->pwr_domain) {
>> 		callback = dev->pwr_domain->ops.runtime_resume;
>> 		if(!strcmp(dev_name(dev),"usbhs_omap"))
>> 			 pr_err("dev->pwr_domain->ops.runtime_resume");
>>
>>
>> due to this; the driver->runtime_resume was not getting called.
>>
>> Any idea on why I am seeing only the dev->pwr_domain is set not
>> dev->bus && dev->bus->pm is hitting here?
>
>Because the PM domain takes precedence over the subsystem for PM
>callbacks.  If the subsystem routine should be called then the PM
>domain code has to call it.

This is taken care of in the pm-domain code:
static int _od_runtime_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);

	omap_device_enable(pdev);

	return pm_generic_runtime_resume(dev);
}
pm_generic_runtime_resume will in turn call the driver call back.

int pm_generic_runtime_resume(struct device *dev)
{
	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm :
NULL;
	int ret;

	ret = pm && pm->runtime_resume ? pm->runtime_resume(dev) : 0;

	return ret;
}
>
>Alan Stern
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