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Date:   Tue, 29 Dec 2020 15:05:36 -0800
From:   Wesley Cheng <wcheng@...eaurora.org>
To:     balbi@...nel.org, gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        Wesley Cheng <wcheng@...eaurora.org>
Subject: [PATCH v2 2/2] usb: dwc3: gadget: Preserve UDC max speed setting

The USB gadget/UDC driver can restrict the DWC3 controller speed using
dwc3_gadget_set_speed().  Store this setting into a variable, in order for
this setting to persist across controller resets due to runtime PM.

Signed-off-by: Wesley Cheng <wcheng@...eaurora.org>
---
 drivers/usb/dwc3/core.h   |   1 +
 drivers/usb/dwc3/gadget.c | 108 ++++++++++++++++++++------------------
 2 files changed, 58 insertions(+), 51 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 2f04b3e42bf1..390d3deef0ba 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1119,6 +1119,7 @@ struct dwc3 {
 	u32			nr_scratch;
 	u32			u1u2;
 	u32			maximum_speed;
+	u32			gadget_max_speed;
 
 	u32			ip;
 
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index babf977cadc0..c145da1d8ba5 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1941,6 +1941,61 @@ static void dwc3_stop_active_transfers(struct dwc3 *dwc)
 	}
 }
 
+static void __dwc3_gadget_set_speed(struct dwc3 *dwc)
+{
+	u32			reg;
+
+	reg = dwc3_readl(dwc->regs, DWC3_DCFG);
+	reg &= ~(DWC3_DCFG_SPEED_MASK);
+
+	/*
+	 * WORKAROUND: DWC3 revision < 2.20a have an issue
+	 * which would cause metastability state on Run/Stop
+	 * bit if we try to force the IP to USB2-only mode.
+	 *
+	 * Because of that, we cannot configure the IP to any
+	 * speed other than the SuperSpeed
+	 *
+	 * Refers to:
+	 *
+	 * STAR#9000525659: Clock Domain Crossing on DCTL in
+	 * USB 2.0 Mode
+	 */
+	if (DWC3_VER_IS_PRIOR(DWC3, 220A) &&
+	    !dwc->dis_metastability_quirk) {
+		reg |= DWC3_DCFG_SUPERSPEED;
+	} else {
+		switch (dwc->gadget_max_speed) {
+		case USB_SPEED_LOW:
+			reg |= DWC3_DCFG_LOWSPEED;
+			break;
+		case USB_SPEED_FULL:
+			reg |= DWC3_DCFG_FULLSPEED;
+			break;
+		case USB_SPEED_HIGH:
+			reg |= DWC3_DCFG_HIGHSPEED;
+			break;
+		case USB_SPEED_SUPER:
+			reg |= DWC3_DCFG_SUPERSPEED;
+			break;
+		case USB_SPEED_SUPER_PLUS:
+			if (DWC3_IP_IS(DWC3))
+				reg |= DWC3_DCFG_SUPERSPEED;
+			else
+				reg |= DWC3_DCFG_SUPERSPEED_PLUS;
+			break;
+		default:
+			dev_err(dwc->dev, "invalid speed (%d)\n", dwc->gadget_max_speed);
+
+			if (DWC3_IP_IS(DWC3))
+				reg |= DWC3_DCFG_SUPERSPEED;
+			else
+				reg |= DWC3_DCFG_SUPERSPEED_PLUS;
+		}
+	}
+	dwc3_writel(dwc->regs, DWC3_DCFG, reg);
+}
+
 static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
 {
 	u32			reg;
@@ -1963,6 +2018,7 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
 		if (dwc->has_hibernation)
 			reg |= DWC3_DCTL_KEEP_CONNECT;
 
+		__dwc3_gadget_set_speed(dwc);
 		dwc->pullups_connected = true;
 	} else {
 		reg &= ~DWC3_DCTL_RUN_STOP;
@@ -2325,59 +2381,9 @@ static void dwc3_gadget_set_speed(struct usb_gadget *g,
 {
 	struct dwc3		*dwc = gadget_to_dwc(g);
 	unsigned long		flags;
-	u32			reg;
 
 	spin_lock_irqsave(&dwc->lock, flags);
-	reg = dwc3_readl(dwc->regs, DWC3_DCFG);
-	reg &= ~(DWC3_DCFG_SPEED_MASK);
-
-	/*
-	 * WORKAROUND: DWC3 revision < 2.20a have an issue
-	 * which would cause metastability state on Run/Stop
-	 * bit if we try to force the IP to USB2-only mode.
-	 *
-	 * Because of that, we cannot configure the IP to any
-	 * speed other than the SuperSpeed
-	 *
-	 * Refers to:
-	 *
-	 * STAR#9000525659: Clock Domain Crossing on DCTL in
-	 * USB 2.0 Mode
-	 */
-	if (DWC3_VER_IS_PRIOR(DWC3, 220A) &&
-	    !dwc->dis_metastability_quirk) {
-		reg |= DWC3_DCFG_SUPERSPEED;
-	} else {
-		switch (speed) {
-		case USB_SPEED_LOW:
-			reg |= DWC3_DCFG_LOWSPEED;
-			break;
-		case USB_SPEED_FULL:
-			reg |= DWC3_DCFG_FULLSPEED;
-			break;
-		case USB_SPEED_HIGH:
-			reg |= DWC3_DCFG_HIGHSPEED;
-			break;
-		case USB_SPEED_SUPER:
-			reg |= DWC3_DCFG_SUPERSPEED;
-			break;
-		case USB_SPEED_SUPER_PLUS:
-			if (DWC3_IP_IS(DWC3))
-				reg |= DWC3_DCFG_SUPERSPEED;
-			else
-				reg |= DWC3_DCFG_SUPERSPEED_PLUS;
-			break;
-		default:
-			dev_err(dwc->dev, "invalid speed (%d)\n", speed);
-
-			if (DWC3_IP_IS(DWC3))
-				reg |= DWC3_DCFG_SUPERSPEED;
-			else
-				reg |= DWC3_DCFG_SUPERSPEED_PLUS;
-		}
-	}
-	dwc3_writel(dwc->regs, DWC3_DCFG, reg);
-
+	dwc->gadget_max_speed = speed;
 	spin_unlock_irqrestore(&dwc->lock, flags);
 }
 
-- 
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