linux-kernel - Re: [PATCH v17 5/5] usb: dwc3: qcom: Keep power domain on to retain controller status

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Message-ID: <20220524102649.GI15121@hu-pkondeti-hyd.qualcomm.com>
Date:   Tue, 24 May 2022 15:56:49 +0530
From:   Pavan Kondeti <quic_pkondeti@...cinc.com>
To:     Krishna Kurapati <quic_kriskura@...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_pkondeti@...cinc.com>,
        <quic_ppratap@...cinc.com>, <quic_vpulyala@...cinc.com>,
        Sandeep Maheswaram <quic_c_sanm@...cinc.com>
Subject: Re: [PATCH v17 5/5] usb: dwc3: qcom: Keep power domain on to retain
 controller status

On Tue, May 24, 2022 at 03:43:48PM +0530, Krishna Kurapati wrote:
> From: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
> 
> If dwc3 is wakeup capable, keep the power domain always ON so that
> wakeup from system suspend can be supported. Otherwise, keep the
> power domain ON only during runtime suspend to support wakeup from
> runtime suspend.
> 
> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
> Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index 5d5db62..7bffb31 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>
> @@ -760,12 +761,13 @@ dwc3_qcom_create_urs_usb_platdev(struct device *dev)
>  
>  static int dwc3_qcom_probe(struct platform_device *pdev)
>  {
> -	struct device_node	*np = pdev->dev.of_node;
> -	struct device		*dev = &pdev->dev;
> -	struct dwc3_qcom	*qcom;
> -	struct resource		*res, *parent_res = NULL;
> -	int			ret, i;
> -	bool			ignore_pipe_clk;
> +	struct device_node *np = pdev->dev.of_node;
> +	struct device *dev = &pdev->dev;
> +	struct dwc3_qcom *qcom;
> +	struct resource	*res, *parent_res = NULL;
> +	int ret, i;
> +	bool ignore_pipe_clk;
> +	struct generic_pm_domain *genpd;
>  
>  	qcom = devm_kzalloc(&pdev->dev, sizeof(*qcom), GFP_KERNEL);
>  	if (!qcom)
> @@ -774,6 +776,8 @@ 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) {
> @@ -881,7 +885,13 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto interconnect_exit;
>  
> -	device_init_wakeup(&pdev->dev, 1);
> +	if (device_can_wakeup(&qcom->dwc3->dev)) {
> +		genpd->flags |= GENPD_FLAG_ALWAYS_ON;
> +		device_init_wakeup(&pdev->dev, true);
> +	} else {
> +		genpd->flags |= GENPD_FLAG_RPM_ALWAYS_ON;
> +	}
> +

Can you please write a comment here explaining why we do this?
commit description has some details already.

Thanks,
Pavan