linux-kernel - Re: [v15 3/6] usb: dwc3: core: Host wake up support from system suspend

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Date:   Thu, 5 May 2022 15:48:31 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
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>,
        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: [v15 3/6] usb: dwc3: core: Host wake up support from system
 suspend

On Thu, May 05, 2022 at 02:26:10PM +0530, Krishna Kurapati wrote:
> From: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
> 
> During suspend read the status of all port and set hs phy mode
> based on current speed. Use this hs phy mode to configure wakeup
> interrupts in qcom glue driver.
> 
> Check wakeup-source property for dwc3 core node to set the
> wakeup capability. Drop the device_init_wakeup call from
> runtime suspend and resume.
> 
> Also check during suspend if any wakeup capable devices are
> connected to the controller (directly or through hubs), if there
> are none set a flag to indicate that the PHY is powered
> down during suspend.
> 
> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
> Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
> ---
>  drivers/usb/dwc3/core.c | 33 ++++++++++++++++++++-------------
>  drivers/usb/dwc3/core.h |  4 ++++
>  drivers/usb/dwc3/host.c | 24 ++++++++++++++++++++++++
>  3 files changed, 48 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 950e238..cf377f5 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -33,6 +33,7 @@
>  #include <linux/usb/gadget.h>
>  #include <linux/usb/of.h>
>  #include <linux/usb/otg.h>
> +#include <linux/usb/hcd.h>

This is not needed anymore

>  
>  #include "core.h"
>  #include "gadget.h"
> @@ -1787,6 +1788,7 @@ 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);
> @@ -1936,6 +1938,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  {
>  	unsigned long	flags;
>  	u32 reg;
> +	struct usb_hcd  *hcd = platform_get_drvdata(dwc->xhci);

This isn't used anymore, delete it

>  
>  	switch (dwc->current_dr_role) {
>  	case DWC3_GCTL_PRTCAP_DEVICE:
> @@ -1948,10 +1951,7 @@ 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;
> -		}
> +		dwc3_check_phy_speed_mode(dwc);
>  
>  		/* Let controller to suspend HSPHY before PHY driver suspends */
>  		if (dwc->dis_u2_susphy_quirk ||
> @@ -1967,6 +1967,16 @@ 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_may_wakeup(dwc->dev) &&
> +					device_wakeup_path(dwc->dev)) {

nit: the indentation is odd, align it with device_may_wakeup()?

> +				dwc->phy_power_off = false;
> +			} else {
> +				dwc->phy_power_off = true;
> +				dwc3_core_exit(dwc);

As commented earlier, taking the controller and PHYs completely down causes a
significant power draw in some USB clients. Let's clarify what the specific
benefits are of doing dwc3_core_exit() vs. entering a low power mode.