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>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index a469999a106d..50398b69ca44 100644
--- 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