linux-kernel - [PATCH v2] usb: dwc3: support continuous runtime PM with dual role

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Message-Id: <20200319084902.24747-1-martin.kepplinger@puri.sm>
Date:   Thu, 19 Mar 2020 09:49:02 +0100
From:   Martin Kepplinger <martin.kepplinger@...i.sm>
To:     balbi@...nel.org
Cc:     gregkh@...uxfoundation.org, rogerq@...com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Martin Kepplinger <martin.kepplinger@...i.sm>
Subject: [PATCH v2] usb: dwc3: support continuous runtime PM with dual role

The DRD module calls dwc3_set_mode() on role switches, i.e. when a device is
being pugged in. In order to support continuous runtime power management when
plugging in / unplugging a cable, we need to call pm_runtime_get() in this path.

Signed-off-by: Martin Kepplinger <martin.kepplinger@...i.sm>
---

revision history
----------------
v2: move pm_rumtime calls into workqueue (thanks Roger)
    remove unrelated documentation patch
v1: https://lore.kernel.org/linux-usb/ef22f8de-9bfd-c1d5-111c-696f1336dbda@puri.sm/T/


 drivers/usb/dwc3/core.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 1d85c42b9c67..0c058b2ac21d 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -121,17 +121,19 @@ static void __dwc3_set_mode(struct work_struct *work)
 	if (dwc->dr_mode != USB_DR_MODE_OTG)
 		return;
 
+	pm_runtime_get(dwc->dev);
+
 	if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_OTG)
 		dwc3_otg_update(dwc, 0);
 
 	if (!dwc->desired_dr_role)
-		return;
+		goto out;
 
 	if (dwc->desired_dr_role == dwc->current_dr_role)
-		return;
+		goto out;
 
 	if (dwc->desired_dr_role == DWC3_GCTL_PRTCAP_OTG && dwc->edev)
-		return;
+		goto out;
 
 	switch (dwc->current_dr_role) {
 	case DWC3_GCTL_PRTCAP_HOST:
@@ -190,6 +192,9 @@ static void __dwc3_set_mode(struct work_struct *work)
 		break;
 	}
 
+out:
+	pm_runtime_mark_last_busy(dwc->dev);
+	pm_runtime_put_autosuspend(dwc->dev);
 }
 
 void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
-- 
2.20.1