patches.renesas/0220-usb-host-xhci-ring-don-t-need-to-clear-interrupt-pen.patch

From 3c19b50440734aca43db7be3feea45aa431b9da4 Mon Sep 17 00:00:00 2001
From: Peter Chen <peter.chen@nxp.com>
Date: Wed, 17 May 2017 18:32:02 +0300
Subject: [PATCH 220/286] usb: host: xhci-ring: don't need to clear interrupt
 pending for MSI enabled hcd

According to xHCI spec Figure 30: Interrupt Throttle Flow Diagram

	If PCI Message Signaled Interrupts (MSI or MSI-X) are enabled,
       	then the assertion of the Interrupt Pending (IP) flag in Figure 30
       	generates a PCI Dword write. The IP flag is automatically cleared
       	by the completion of the PCI write.

the MSI enabled HCs don't need to clear interrupt pending bit, but
hcd->irq = 0 doesn't equal to MSI enabled HCD. At some Dual-role
controller software designs, it sets hcd->irq as 0 to avoid HCD
requesting interrupt, and they want to decide when to call usb_hcd_irq
by software.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 6a29beef9d1b16c762e469d77e28c3de3f5c3dbb)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
---
 drivers/usb/host/xhci-ring.c |    5 +----
 drivers/usb/host/xhci.c      |    5 +++--
 include/linux/usb/hcd.h      |    1 +
 3 files changed, 5 insertions(+), 6 deletions(-)

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2710,12 +2710,9 @@ irqreturn_t xhci_irq(struct usb_hcd *hcd
 	 */
 	status |= STS_EINT;
 	writel(status, &xhci->op_regs->status);
-	/* FIXME when MSI-X is supported and there are multiple vectors */
-	/* Clear the MSI-X event interrupt status */
 
-	if (hcd->irq) {
+	if (!hcd->msi_enabled) {
 		u32 irq_pending;
-		/* Acknowledge the PCI interrupt */
 		irq_pending = readl(&xhci->ir_set->irq_pending);
 		irq_pending |= IMAN_IP;
 		writel(irq_pending, &xhci->ir_set->irq_pending);
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -401,9 +401,10 @@ static int xhci_try_enable_msi(struct us
 		/* fall back to msi*/
 		ret = xhci_setup_msi(xhci);
 
-	if (!ret)
-		/* hcd->irq is 0, we have MSI */
+	if (!ret) {
+		hcd->msi_enabled = 1;
 		return 0;
+	}
 
 	if (!pdev->irq) {
 		xhci_err(xhci, "No msi-x/msi found and no IRQ in BIOS\n");
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -148,6 +148,7 @@ struct usb_hcd {
 	unsigned		rh_registered:1;/* is root hub registered? */
 	unsigned		rh_pollable:1;	/* may we poll the root hub? */
 	unsigned		msix_enabled:1;	/* driver has MSI-X enabled? */
+	unsigned		msi_enabled:1;	/* driver has MSI enabled? */
 	unsigned		remove_phy:1;	/* auto-remove USB phy */
 
 	/* The next flag is a stopgap, to be removed when all the HCDs