linux-kernel - [PATCH] usb: xhci: Workaround for erratum-A010129

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Date:   Fri, 21 Oct 2016 19:41:49 +0530
From:   Sriram Dash <sriram.dash@....com>
To:     <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>
CC:     <mathias.nyman@...el.com>, <gregkh@...uxfoundation.org>,
        <suresh.gupta@....com>, <felipe.balbi@...ux.intel.com>,
        Sriram Dash <sriram.dash@....com>,
        Rajat Srivastava <rajat.srivastava@....com>,
        Rajesh Bhagat <rajesh.bhagat@....com>
Subject: [PATCH] usb: xhci: Workaround for erratum-A010129

For the USB3.0 controller, USB 2.0 reset not driven while
port is in Resume state. So, do not program the USB 2.0 reset
(PORTSC[PR]=1) while in Resume state.

Signed-off-by: Rajat Srivastava <rajat.srivastava@....com>
Signed-off-by: Sriram Dash <sriram.dash@....com>
Signed-off-by: Rajesh Bhagat <rajesh.bhagat@....com>
---
 drivers/usb/host/xhci-hub.c | 28 +++++++++++++++++++++++++++-
 drivers/usb/host/xhci.h     |  1 +
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 730b9fd..3def0dd 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -878,7 +878,7 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
 	int max_ports;
 	unsigned long flags;
-	u32 temp, status;
+	u32 temp, status, tmp_status = 0;
 	int retval = 0;
 	__le32 __iomem **port_array;
 	int slot_id;
@@ -1098,6 +1098,32 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 			spin_lock_irqsave(&xhci->lock, flags);
 			break;
 		case USB_PORT_FEAT_RESET:
+			/*
+			 * Erratum : A010129
+			 * Synopsys STAR 9000962562.
+			 * USB 2.0 Reset Not Driven While Port in Resume
+			 * While in USB 2.0 resume state (the PORTSC.PLS
+			 * register bit is set to 4'd15), if the xHCI driver
+			 * programs the PORTSC.PR register bit to 1, the
+			 * controller does not drive a USB 2.0 reset
+			 * and it does not generate a PORTSC.PRC=1 interrupt.
+			 * So, The xHCI driver should not program a USB
+			 * 2.0 reset (PORTSC.PR=1) while in resume
+			 * (PORTSC.PLS=4'd15).
+			 */
+			if (xhci->quirks & XHCI_PORT_RST_ON_RESUME) {
+				tmp_status = readl(port_array[wIndex]);
+				spin_unlock_irqrestore(&xhci->lock, flags);
+				if (!DEV_SUPERSPEED(tmp_status)
+					&& (tmp_status & PORT_PLS_MASK)
+					== XDEV_RESUME) {
+					xhci_err(xhci, "skip port reset\n");
+					spin_lock_irqsave(&xhci->lock, flags);
+					break;
+				}
+				spin_lock_irqsave(&xhci->lock, flags);
+			}
+
 			temp = (temp | PORT_RESET);
 			writel(temp, port_array[wIndex]);
 
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index b2c1dc5..c07e267 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1653,6 +1653,7 @@ struct xhci_hcd {
 #define XHCI_MTK_HOST		(1 << 21)
 #define XHCI_SSIC_PORT_UNUSED	(1 << 22)
 #define XHCI_NO_64BIT_SUPPORT	(1 << 23)
+#define XHCI_PORT_RST_ON_RESUME	(1 << 24)
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;
 	/* There are two roothubs to keep track of bus suspend info for */
-- 
2.1.0