linux-kernel - RE: [PATCH] usb/core: skip unnecessary line IRQ request for USB3

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Date:	Thu, 15 Mar 2012 14:37:47 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	"Xu, Andiry" <Andiry.Xu@....com>
Cc:	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	gregkh <gregkh@...uxfoundation.org>,
	"sarah.a.sharp@...ux.intel.com" <sarah.a.sharp@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-usb <linux-usb@...r.kernel.org>
Subject: RE: [PATCH] usb/core: skip unnecessary line IRQ request for USB3


> 
> You may also remove the unregister the legacy interrupt part in
> xhci_try_enable_msi().

Sure, thanks!

>>From 6ae16651ae33ea1841984f3a5eb4a691ed730a19 Mon Sep 17 00:00:00 2001
From: Alex Shi <alex.shi@...el.com>
Date: Thu, 15 Mar 2012 08:12:47 +0800
Subject: [PATCH] usb/core: skip unnecessary line IRQ request for USB3

USB3(only xhci driver) requests line IRQ here but will disable it
in later driver->start function and try MSI first:

xhci_hcd 0000:02:00.0: irq 18, io mem 0xfe500000
xhci_hcd 0000:02:00.0: irq 45 for MSI/MSI-X
xhci_hcd 0000:02:00.0: irq 46 for MSI/MSI-X

So it is better to remove the redundant request here.

Signed-off-by: Alex Shi <alex.shi@...el.com>
---
 drivers/usb/core/hcd.c  |    3 ++-
 drivers/usb/host/xhci.c |    3 ---
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index e128232..5b09825 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2450,7 +2450,8 @@ int usb_add_hcd(struct usb_hcd *hcd,
 	/* enable irqs just before we start the controller,
 	 * if the BIOS provides legacy PCI irqs.
 	 */
-	if (usb_hcd_is_primary_hcd(hcd) && irqnum) {
+	if (usb_hcd_is_primary_hcd(hcd) && irqnum
+		&& (hcd->driver->flags & HCD_MASK) != HCD_USB3) {
 		retval = usb_hcd_request_irqs(hcd, irqnum, irqflags);
 		if (retval)
 			goto err_request_irq;
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index c939f5f..64979c2 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -338,9 +338,6 @@ static int xhci_try_enable_msi(struct usb_hcd *hcd)
 	if (xhci->quirks & XHCI_BROKEN_MSI)
 		return 0;
 
-	/* unregister the legacy interrupt */
-	if (hcd->irq)
-		free_irq(hcd->irq, hcd);
 	hcd->irq = -1;
 
 	ret = xhci_setup_msix(xhci);
-- 
1.6.3.3


> 
> In fact, I think all the MSI related codes should be moved to xhci-pci.c,
> Since MSI is PCI-only.

A patch moving MSI from xhci to USB core is in reviewing. That walks
far. :) https://lkml.org/lkml/2012/2/20/76 


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