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

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Date:   Fri, 6 May 2022 10:44:48 +0530
From:   Pavan Kondeti <quic_pkondeti@...cinc.com>
To:     Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
CC:     Matthias Kaehlcke <mka@...omium.org>,
        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 Fri, May 06, 2022 at 10:41:01AM +0530, Krishna Kurapati PSSNV wrote:
> 
> On 5/6/2022 4:18 AM, Matthias Kaehlcke wrote:
> >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
> My bad, Will fix this in next version.
> >>  	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()?
> Sure, Will take care of it.
> >>+				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.
> Sure, once we come to a conclusion on this, I will refresh the patches.

I think, Matthias is asking you to clarify in the commit description. we can
even quote Matthias observations.

Thanks,
Pavan