linux-kernel - Re: [PATCH 6/6] USB: ehci-omap: Implement suspend/resume

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Date:	Mon, 22 Jul 2013 11:18:46 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Roger Quadros <rogerq@...com>
cc:	gregkh@...uxfoundation.org, <balbi@...com>,
	<sergei.shtylyov@...entembedded.com>, <khilman@...aro.org>,
	<tony@...mide.com>, <ruslan.bilovol@...com>,
	<linux-usb@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 6/6] USB: ehci-omap: Implement suspend/resume

On Mon, 22 Jul 2013, Roger Quadros wrote:

> Right, I understand it now. How does the below code look?
> 
> +static int omap_ehci_suspend(struct device *dev)
> +{
> +       struct usb_hcd *hcd = dev_get_drvdata(dev);
> +       bool do_wakeup = device_may_wakeup(dev);
> +       int ret;
> +
> +       dev_dbg(dev, "%s may_wakeup %d\n", __func__, do_wakeup);
> +
> +       if (pm_runtime_status_suspended(dev)) {

You need to do this only when do_wakeup is false.

> +               pm_runtime_get_sync(dev);
> +               ehci_resume(hcd, false);
> +               ret = ehci_suspend(hcd, do_wakeup);
> +               pm_runtime_put_sync(dev);

It would be better to call pm_runtime_resume(dev) at the start instead
of pm_runtime_get_sync(), and eliminate the last two lines.  Then the
ehci_suspend() below could be moved outside the "if" statement.

Alternatively, if you are able to turn off the wakeup setting without
going through an entire resume/suspend cycle, that would be preferable.

> +
> +       } else {
> +               ret = ehci_suspend(hcd, do_wakeup);
> +       }
> +
> +       return ret;
> +}
> +
> +static int omap_ehci_resume(struct device *dev)
> +{
> +       struct usb_hcd *hcd = dev_get_drvdata(dev);
> +       int ret;
> +
> +       dev_dbg(dev, "%s\n", __func__);
> +
> +       ret = ehci_resume(hcd, false);
> +       if (!ret) {
> +               /*
> +                * Controller was powered ON so reflect state
> +                */
> +               pm_runtime_disable(dev);
> +               pm_runtime_set_active(dev);
> +               pm_runtime_enable(dev);
> +       }
> +
> +       return ret;
> +}

All good.

Alan Stern

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