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usb: host: xhci-ring: don't need to clear interrupt pending for MSI enabled hcd

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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>
This commit is contained in:
Peter Chen
2017-05-17 18:32:02 +03:00
committed by Greg Kroah-Hartman
parent 7480d912d5
commit 6a29beef9d
3 changed files with 5 additions and 6 deletions
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1
include/linux/usb/hcd.h
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@@ -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