linux-kernel - [PATCH 4.9 057/164] ohci-pci: add qemu quirk

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Date:   Tue, 23 May 2017 22:07:54 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Gerd Hoffmann <kraxel@...hat.com>,
        Alan Stern <stern@...land.harvard.edu>
Subject: [PATCH 4.9 057/164] ohci-pci: add qemu quirk

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gerd Hoffmann <kraxel@...hat.com>

commit 21a60f6e65181cad64fd66ccc8080d413721ba27 upstream.

On a loaded virtualization host (dozen guests booting at the same time)
it may happen that the ohci controller emulation doesn't manage to do
timely frame processing, with the result that the io watchdog fires and
considers the controller being dead, even though it's only the emulation
being unusual slow due to the load peak.

So, add a quirk for qemu and don't use the watchdog in case we figure we
are running on emulated ohci.  The virtual ohci controller masquerades
as apple ohci controller, but we can identify it by subsystem id.

Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
Signed-off-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/host/ohci-hcd.c |    3 ++-
 drivers/usb/host/ohci-pci.c |   16 ++++++++++++++++
 drivers/usb/host/ohci.h     |    1 +
 3 files changed, 19 insertions(+), 1 deletion(-)

--- a/drivers/usb/host/ohci-hcd.c
+++ b/drivers/usb/host/ohci-hcd.c
@@ -231,7 +231,8 @@ static int ohci_urb_enqueue (
 
 		/* Start up the I/O watchdog timer, if it's not running */
 		if (!timer_pending(&ohci->io_watchdog) &&
-				list_empty(&ohci->eds_in_use)) {
+				list_empty(&ohci->eds_in_use) &&
+				!(ohci->flags & OHCI_QUIRK_QEMU)) {
 			ohci->prev_frame_no = ohci_frame_no(ohci);
 			mod_timer(&ohci->io_watchdog,
 					jiffies + IO_WATCHDOG_DELAY);
--- a/drivers/usb/host/ohci-pci.c
+++ b/drivers/usb/host/ohci-pci.c
@@ -164,6 +164,15 @@ static int ohci_quirk_amd700(struct usb_
 	return 0;
 }
 
+static int ohci_quirk_qemu(struct usb_hcd *hcd)
+{
+	struct ohci_hcd *ohci = hcd_to_ohci(hcd);
+
+	ohci->flags |= OHCI_QUIRK_QEMU;
+	ohci_dbg(ohci, "enabled qemu quirk\n");
+	return 0;
+}
+
 /* List of quirks for OHCI */
 static const struct pci_device_id ohci_pci_quirks[] = {
 	{
@@ -214,6 +223,13 @@ static const struct pci_device_id ohci_p
 		PCI_DEVICE(PCI_VENDOR_ID_ATI, 0x4399),
 		.driver_data = (unsigned long)ohci_quirk_amd700,
 	},
+	{
+		.vendor		= PCI_VENDOR_ID_APPLE,
+		.device		= 0x003f,
+		.subvendor	= PCI_SUBVENDOR_ID_REDHAT_QUMRANET,
+		.subdevice	= PCI_SUBDEVICE_ID_QEMU,
+		.driver_data	= (unsigned long)ohci_quirk_qemu,
+	},
 
 	/* FIXME for some of the early AMD 760 southbridges, OHCI
 	 * won't work at all.  blacklist them.
--- a/drivers/usb/host/ohci.h
+++ b/drivers/usb/host/ohci.h
@@ -418,6 +418,7 @@ struct ohci_hcd {
 #define	OHCI_QUIRK_AMD_PLL	0x200			/* AMD PLL quirk*/
 #define	OHCI_QUIRK_AMD_PREFETCH	0x400			/* pre-fetch for ISO transfer */
 #define	OHCI_QUIRK_GLOBAL_SUSPEND	0x800		/* must suspend ports */
+#define	OHCI_QUIRK_QEMU		0x1000			/* relax timing expectations */
 
 	// there are also chip quirks/bugs in init logic