linux-kernel - Re: [PATCH v13 5/6] usb: dwc3: qcom: Keep power domain on to retain controller status

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Message-ID: <8ab040bb-0328-1f7a-cf1b-7497fe4b69a0@quicinc.com>
Date:   Tue, 12 Apr 2022 10:20:24 +0530
From:   "Sandeep Maheswaram (Temp)" <quic_c_sanm@...cinc.com>
To:     Matthias Kaehlcke <mka@...omium.org>
CC:     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>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        <devicetree@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_pkondeti@...cinc.com>, <quic_ppratap@...cinc.com>,
        <quic_kriskura@...cinc.com>, <quic_vpulyala@...cinc.com>
Subject: Re: [PATCH v13 5/6] usb: dwc3: qcom: Keep power domain on to retain
 controller status

Hi,

On 4/12/2022 2:43 AM, Matthias Kaehlcke wrote:
> On Tue, Apr 12, 2022 at 12:46:53AM +0530, Sandeep Maheswaram wrote:
>> Keep the power domain always on during runtime suspend or if the
>> controller supports wakeup in order to retain controller status
>> and to support wakeup from devices.
>>
>> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
>> ---
>>   drivers/usb/dwc3/dwc3-qcom.c | 11 ++++++++++-
>>   1 file changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
>> index 9804a19..9747be6 100644
>> --- a/drivers/usb/dwc3/dwc3-qcom.c
>> +++ b/drivers/usb/dwc3/dwc3-qcom.c
>> @@ -17,6 +17,7 @@
>>   #include <linux/of_platform.h>
>>   #include <linux/platform_device.h>
>>   #include <linux/phy/phy.h>
>> +#include <linux/pm_domain.h>
>>   #include <linux/usb/of.h>
>>   #include <linux/reset.h>
>>   #include <linux/iopoll.h>
>> @@ -724,6 +725,7 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>>   	struct resource		*res, *parent_res = NULL;
>>   	int			ret, i;
>>   	bool			ignore_pipe_clk;
>> +	struct generic_pm_domain *genpd;
> nit: I'm not really a fan of gazillions of whitespaces between the type
> and the variable name, but if they are kept all variable names above
> should move a tab to the right. In any case the style in this file isn't
> consistent, so an alternative would be to just get rid of the alignment
> completely.
Okay. Will do it in next version.
>
>>   	qcom = devm_kzalloc(&pdev->dev, sizeof(*qcom), GFP_KERNEL);
>>   	if (!qcom)
>> @@ -732,6 +734,8 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>>   	platform_set_drvdata(pdev, qcom);
>>   	qcom->dev = &pdev->dev;
>>   
>> +	genpd = pd_to_genpd(qcom->dev->pm_domain);
>> +
>>   	if (has_acpi_companion(dev)) {
>>   		qcom->acpi_pdata = acpi_device_get_match_data(dev);
>>   		if (!qcom->acpi_pdata) {
>> @@ -839,7 +843,12 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>>   	if (ret)
>>   		goto interconnect_exit;
>>   
>> -	device_init_wakeup(&pdev->dev, 1);
>> +	genpd->flags |= GENPD_FLAG_RPM_ALWAYS_ON;
>> +
>> +	if (device_may_wakeup(&qcom->dwc3->dev))
>> +		genpd->flags |= GENPD_FLAG_ALWAYS_ON;
> In v12 only GENPD_FLAG_ALWAYS_ON was set, not GENPD_FLAG_RPM_ALWAYS_ON.
> I asked a few times for a change log, in this instance it would be
> useful to explain why GENPD_FLAG_RPM_ALWAYS_ON is now set.
Okay. Will add it in next version.
>
>> +
>> +	device_init_wakeup(&pdev->dev, device_may_wakeup(&qcom->dwc3->dev));
> device_may_wakeup() isn't an expensive operation, but it's still not nice to
> call it twice in three lines of code. Instead you could do this:
>
> 	if (device_may_wakeup(&qcom->dwc3->dev)) {
> 		genpd->flags |= GENPD_FLAG_ALWAYS_ON;
> 		device_init_wakeup(&pdev->dev, true);
> 	}
Okay. Will do it in next version.