linux-kernel - Re: [PATCH 2/8] Revert "usb: dwc3: qcom: Keep power domain on to retain controller status"

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Date:   Tue, 2 Aug 2022 23:30:34 +0530
From:   Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To:     Johan Hovold <johan+linaro@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <balbi@...nel.org>
CC:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Andy Gross <agross@...nel.org>,
        "Bjorn Andersson" <bjorn.andersson@...aro.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Stephen Boyd <swboyd@...omium.org>,
        "Doug Anderson" <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Pavankumar Kondeti <quic_pkondeti@...cinc.com>,
        <quic_ppratap@...cinc.com>, <quic_vpulyala@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/8] Revert "usb: dwc3: qcom: Keep power domain on to
 retain controller status"


On 8/2/2022 8:43 PM, Johan Hovold wrote:
> This reverts commit d9be8d5c5b032e5383ff5c404ff4155e9c705429.
>
> Generic power-domain flags must be set before the power-domain is
> initialised and must specifically not be modified by drivers for devices
> that happen to be in the domain.
>
> To make sure that USB power-domains are left enabled during system
> suspend when a device in the domain is in the wakeup path, the
> GENPD_FLAG_ACTIVE_WAKEUP flag should instead be set for the domain
> unconditionally when it is registered.
Hi Johan, Thanks for the review and suggestion.

In case we need the genpd framework to set the GENPD_FLAG_ACTIVE_WAKEUP
flag for a particular domain that will be used by a device (which is
wakeup capable) and hasn't been probed yet , can you help me understand if
there any dt-flags we  can add to convey the same the genpd  framework
so that it will set that flag during domain registration ?

Regards,
Krishna,
>
> Note that this also avoids keeping power-domains on during suspend when
> wakeup has not been enabled (e.g. through sysfs).
>
> For the runtime PM case, making sure that the PHYs are not suspended and
> that they are in the same domain as the controller prevents the domain
> from being suspended. If there are cases where this is not possible or
> desirable, the genpd implementation may need to be extended.
>
> Fixes: d9be8d5c5b03 ("usb: dwc3: qcom: Keep power domain on to retain controller status")
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> ---
>   drivers/usb/dwc3/dwc3-qcom.c | 28 +++++++---------------------
>   1 file changed, 7 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index c5e482f53e9d..be2e3dd36440 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -17,7 +17,6 @@
>   #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>
> @@ -757,13 +756,12 @@ 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 generic_pm_domain *genpd;
> +	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;
>   
>   	qcom = devm_kzalloc(&pdev->dev, sizeof(*qcom), GFP_KERNEL);
>   	if (!qcom)
> @@ -772,8 +770,6 @@ 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) {
> @@ -881,17 +877,7 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto interconnect_exit;
>   
> -	if (device_can_wakeup(&qcom->dwc3->dev)) {
> -		/*
> -		 * Setting GENPD_FLAG_ALWAYS_ON flag takes care of keeping
> -		 * genpd on in both runtime suspend and system suspend cases.
> -		 */
> -		genpd->flags |= GENPD_FLAG_ALWAYS_ON;
> -		device_init_wakeup(&pdev->dev, true);
> -	} else {
> -		genpd->flags |= GENPD_FLAG_RPM_ALWAYS_ON;
> -	}
> -
> +	device_init_wakeup(&pdev->dev, 1);
>   	qcom->is_suspended = false;
>   	pm_runtime_set_active(dev);
>   	pm_runtime_enable(dev);