linux-kernel - Re: [PATCH v7 1/2] usb: xhci: plat: Enable runtime PM

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Date:   Wed, 14 Dec 2016 01:43:21 -0500
From:   Robert Foss <robert.foss@...labora.com>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     mathias.nyman@...el.com, Greg KH <gregkh@...uxfoundation.org>,
        Julius Werner <jwerner@...omium.org>,
        Andrew Bresticker <abrestic@...omium.org>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Brian Norris <briannorris@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 1/2] usb: xhci: plat: Enable runtime PM

Hey Baolin,

On 2016-12-12 12:21 AM, Baolin Wang wrote:
> Hi Robert,
>
> On 2 December 2016 at 05:46, Robert Foss <robert.foss@...labora.com> wrote:
>> Enable runtime PM for the xhci-plat device so that the parent device
>> may implement runtime PM.
>>
>> Signed-off-by: Robert Foss <robert.foss@...labora.com>
>>
>> Tested-by: Robert Foss <robert.foss@...labora.com>
>> ---
>>  drivers/usb/host/xhci-plat.c | 29 +++++++++++++++++++++++++++--
>>  1 file changed, 27 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
>> index ed56bf9ed885..ba4efe74f537 100644
>> --- a/drivers/usb/host/xhci-plat.c
>> +++ b/drivers/usb/host/xhci-plat.c
>> @@ -246,6 +246,9 @@ static int xhci_plat_probe(struct platform_device *pdev)
>>         if (ret)
>>                 goto dealloc_usb2_hcd;
>>
>> +       pm_runtime_set_active(&pdev->dev);
>> +       pm_runtime_enable(&pdev->dev);
>
> You did not implement the runtime callbacks of xHCI device, then how
> can the parent device control the resume/suspend of xHCI device by
> runtime PM mechanism? Could you see my previous patch which implement
> the runtime callbacks for xHCI device?
> https://lkml.org/lkml/2016/11/28/25
>

Pardon my ignorance, but which exact functions need to be implemented?
Also, does the lkml link you provided contain an example implementation 
of those functions?

>> +
>>         return 0;
>>
>>
>> @@ -274,6 +277,8 @@ static int xhci_plat_remove(struct platform_device *dev)
>>         struct xhci_hcd *xhci = hcd_to_xhci(hcd);
>>         struct clk *clk = xhci->clk;
>>
>> +       pm_runtime_disable(&dev->dev);
>> +
>>         usb_remove_hcd(xhci->shared_hcd);
>>         usb_phy_shutdown(hcd->usb_phy);
>>
>> @@ -292,6 +297,13 @@ static int xhci_plat_suspend(struct device *dev)
>>  {
>>         struct usb_hcd  *hcd = dev_get_drvdata(dev);
>>         struct xhci_hcd *xhci = hcd_to_xhci(hcd);
>> +       int ret;
>> +
>> +       ret = pm_runtime_get_sync(dev);
>> +       if (ret < 0) {
>> +               pm_runtime_put(dev);
>> +               return ret;
>> +       }
>>
>>         /*
>>          * xhci_suspend() needs `do_wakeup` to know whether host is allowed
>> @@ -301,15 +313,28 @@ static int xhci_plat_suspend(struct device *dev)
>>          * reconsider this when xhci_plat_suspend enlarges its scope, e.g.,
>>          * also applies to runtime suspend.
>>          */
>> -       return xhci_suspend(xhci, device_may_wakeup(dev));
>> +       ret = xhci_suspend(xhci, device_may_wakeup(dev));
>> +       pm_runtime_put(dev);
>> +
>> +       return ret;
>>  }
>>
>>  static int xhci_plat_resume(struct device *dev)
>>  {
>>         struct usb_hcd  *hcd = dev_get_drvdata(dev);
>>         struct xhci_hcd *xhci = hcd_to_xhci(hcd);
>> +       int ret;
>>
>> -       return xhci_resume(xhci, 0);
>> +       ret = pm_runtime_get_sync(dev);
>> +       if (ret < 0) {
>> +               pm_runtime_put(dev);
>> +               return ret;
>> +       }
>> +
>> +       ret = xhci_resume(xhci, 0);
>> +       pm_runtime_put(dev);
>> +
>> +       return ret;
>>  }
>>
>>  static const struct dev_pm_ops xhci_plat_pm_ops = {
>> --
>> 2.11.0
>>
>
>
>