USB: EHCI: remove PORT_RWC_BITS when clearing USB_PORT_FEAT_ENABLE

In the ClearPortFeature/USB_PORT_FEAT_ENABLE case, ehci_hub_control()
would read from status_reg, clear PORT_PE, and write the result back to
status_reg. This would clear any bits in PORT_RWC_BITS that were set in
the registers. Fix this by masking these bits off before the write.

Since this masking is common across all ClearPortFeature cases, move it
into a single early location to avoid duplicating it.

Remove the same bugfix from ehci-tegra.c's tegra_ehci_hub_control(), now
that this case is correctly handled by the core.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-hub.c

@@ -704,6 +704,7 @@ static int ehci_hub_control (
 			goto error;
 		wIndex--;
 		temp = ehci_readl(ehci, status_reg);
+		temp &= ~PORT_RWC_BITS;
 
 		/*
 		 * Even if OWNER is set, so the port is owned by the
@@ -717,8 +718,7 @@ static int ehci_hub_control (
 			ehci_writel(ehci, temp & ~PORT_PE, status_reg);
 			break;
 		case USB_PORT_FEAT_C_ENABLE:
-			ehci_writel(ehci, (temp & ~PORT_RWC_BITS) | PORT_PEC,
-					status_reg);
+			ehci_writel(ehci, temp | PORT_PEC, status_reg);
 			break;
 		case USB_PORT_FEAT_SUSPEND:
 			if (temp & PORT_RESET)
@@ -747,7 +747,7 @@ static int ehci_hub_control (
 				spin_lock_irqsave(&ehci->lock, flags);
 			}
 			/* resume signaling for 20 msec */
-			temp &= ~(PORT_RWC_BITS | PORT_WAKE_BITS);
+			temp &= ~PORT_WAKE_BITS;
 			ehci_writel(ehci, temp | PORT_RESUME, status_reg);
 			ehci->reset_done[wIndex] = jiffies
 					+ msecs_to_jiffies(20);
@@ -757,9 +757,8 @@ static int ehci_hub_control (
 			break;
 		case USB_PORT_FEAT_POWER:
 			if (HCS_PPC (ehci->hcs_params))
-				ehci_writel(ehci,
-					  temp & ~(PORT_RWC_BITS | PORT_POWER),
-					  status_reg);
+				ehci_writel(ehci, temp & ~PORT_POWER,
+						status_reg);
 			break;
 		case USB_PORT_FEAT_C_CONNECTION:
 			if (ehci->has_lpm) {
@@ -767,12 +766,10 @@ static int ehci_hub_control (
 				temp &= ~PORT_LPM;
 				temp &= ~PORT_DEV_ADDR;
 			}
-			ehci_writel(ehci, (temp & ~PORT_RWC_BITS) | PORT_CSC,
-					status_reg);
+			ehci_writel(ehci, temp | PORT_CSC, status_reg);
 			break;
 		case USB_PORT_FEAT_C_OVER_CURRENT:
-			ehci_writel(ehci, (temp & ~PORT_RWC_BITS) | PORT_OCC,
-					status_reg);
+			ehci_writel(ehci, temp | PORT_OCC, status_reg);
 			break;
 		case USB_PORT_FEAT_C_RESET:
 			/* GetPortStatus clears reset */

drivers/usb/host/ehci-tegra.c

@@ -148,18 +148,7 @@ static int tegra_ehci_hub_control(
 
 	spin_lock_irqsave(&ehci->lock, flags);
 
-	/*
-	 * In ehci_hub_control() for USB_PORT_FEAT_ENABLE clears the other bits
-	 * that are write on clear, by writing back the register read value, so
-	 * USB_PORT_FEAT_ENABLE is handled by masking the set on clear bits
-	 */
-	if (typeReq == ClearPortFeature && wValue == USB_PORT_FEAT_ENABLE) {
-		temp = ehci_readl(ehci, status_reg) & ~PORT_RWC_BITS;
-		ehci_writel(ehci, temp & ~PORT_PE, status_reg);
-		goto done;
-	}
-
-	else if (typeReq == GetPortStatus) {
+	if (typeReq == GetPortStatus) {
 		temp = ehci_readl(ehci, status_reg);
 		if (tegra->port_resuming && !(temp & PORT_SUSPEND)) {
 			/* Resume completed, re-enable disconnect detection */