linux-kernel - Re: [PATCH v18 2/5] usb: dwc3: core: Host wake up support from system suspend

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Date:   Fri, 27 May 2022 11:42:00 +0530
From:   Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To:     Pavan Kondeti <quic_pkondeti@...cinc.com>
CC:     Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <balbi@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...omium.org>,
        "Matthias Kaehlcke" <mka@...omium.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        <devicetree@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <quic_ppratap@...cinc.com>,
        <quic_vpulyala@...cinc.com>,
        Sandeep Maheswaram <quic_c_sanm@...cinc.com>
Subject: Re: [PATCH v18 2/5] usb: dwc3: core: Host wake up support from system
 suspend


On 5/26/2022 8:13 AM, Pavan Kondeti wrote:
> On Wed, May 25, 2022 at 11:50:23PM +0530, Krishna Kurapati wrote:
>> From: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
>>
>> Check wakeup-source property for dwc3 core node to set the
>> wakeup capability. Drop the device_init_wakeup call from
>> runtime suspend and resume.
>>
>> If the dwc3 is wakeup capable, don't power down the USB PHY(s).
>> The glue drivers are expected to take care of configuring the
>> additional wakeup settings if needed based on the dwc3 wakeup
>> capability status. In some SOC designs, powering off the PHY is
>> resulting in higher leakage, so this patch save power on such boards.
>>
>> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
>> Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
>> Reviewed-by: Pavankumar Kondeti <quic_pkondeti@...cinc.com>
>> Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
>> ---
>>   drivers/usb/dwc3/core.c | 26 ++++++++++++--------------
>>   1 file changed, 12 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index e027c04..2b1b3f7 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -1787,6 +1787,7 @@ static int dwc3_probe(struct platform_device *pdev)
>>   
>>   	platform_set_drvdata(pdev, dwc);
>>   	dwc3_cache_hwparams(dwc);
>> +	device_init_wakeup(&pdev->dev, of_property_read_bool(dev->of_node, "wakeup-source"));
>>   
>>   	spin_lock_init(&dwc->lock);
>>   	mutex_init(&dwc->mutex);
>> @@ -1948,11 +1949,6 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>>   		dwc3_core_exit(dwc);
>>   		break;
>>   	case DWC3_GCTL_PRTCAP_HOST:
>> -		if (!PMSG_IS_AUTO(msg)) {
>> -			dwc3_core_exit(dwc);
>> -			break;
>> -		}
>> -
>>   		/* Let controller to suspend HSPHY before PHY driver suspends */
>>   		if (dwc->dis_u2_susphy_quirk ||
>>   		    dwc->dis_enblslpm_quirk) {
>> @@ -1967,6 +1963,11 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>>   
>>   		phy_pm_runtime_put_sync(dwc->usb2_generic_phy);
>>   		phy_pm_runtime_put_sync(dwc->usb3_generic_phy);
>> +
>> +		if (!PMSG_IS_AUTO(msg)) {
>> +			if (!device_can_wakeup(dwc->dev))
>> +				dwc3_core_exit(dwc);
>> +		}
>>   		break;
> Earlier, the dwc3 which does not support wakeup just calls dwc3_core_exit().
> With this patch we are modifying the behavior. Is that intentional? I expect
> it to be something like
>
> @@ -1761,8 +1782,10 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>                  break;
>          case DWC3_GCTL_PRTCAP_HOST:
>                  if (!PMSG_IS_AUTO(msg)) {
> -                       dwc3_core_exit(dwc);
> -                       break;
> +                       if (!device_can_wakeup(dwc->dev)) {
> +                               dwc3_core_exit(dwc);
> +                               break;
> +                       }
>                  }
>
>                  /* Let controller to suspend HSPHY before PHY driver suspends */
>
> Thanks,
> Pavan

Hi Pavan,

Thanks for pointing out that we are changing behavior. Will try to fix 
it in next series.


Thanks,

Krishna,