USB: add flag for HCDs that can't receive wakeup requests (isp1760-hcd)

commit 074f9dd5 upstream.

Currently the USB stack assumes that all host controller drivers are
capable of receiving wakeup requests from downstream devices.
However, this isn't true for the isp1760-hcd driver, which means that
it isn't safe to do a runtime suspend of any device attached to a
root-hub port if the device requires wakeup.

This patch adds a "cant_recv_wakeups" flag to the usb_hcd structure
and sets the flag in isp1760-hcd.  The core is modified to prevent a
direct child of the root hub from being put into runtime suspend with
wakeup enabled if the flag is set.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/usb/core/driver.c

@@ -1800,6 +1800,18 @@ static int autosuspend_check(struct usb_device *udev)
 		dev_dbg(&udev->dev, "remote wakeup needed for autosuspend\n");
 		return -EOPNOTSUPP;
 	}
+
+	/*
+	 * If the device is a direct child of the root hub and the HCD
+	 * doesn't handle wakeup requests, don't allow autosuspend when
+	 * wakeup is needed.
+	 */
+	if (w && udev->parent == udev->bus->root_hub &&
+			bus_to_hcd(udev->bus)->cant_recv_wakeups) {
+		dev_dbg(&udev->dev, "HCD doesn't handle wakeup requests\n");
+		return -EOPNOTSUPP;
+	}
+
 	udev->do_remote_wakeup = w;
 	return 0;
 }

drivers/usb/host/isp1760-hcd.c

@@ -2247,6 +2247,9 @@ struct usb_hcd *isp1760_register(phys_addr_t res_start, resource_size_t res_len,
 	hcd->rsrc_start = res_start;
 	hcd->rsrc_len = res_len;
 
+	/* This driver doesn't support wakeup requests */
+	hcd->cant_recv_wakeups = 1;
+
 	ret = usb_add_hcd(hcd, irq, irqflags);
 	if (ret)
 		goto err_unmap;

include/linux/usb/hcd.h

@@ -144,6 +144,8 @@ struct usb_hcd {
 	unsigned		has_tt:1;	/* Integrated TT in root hub */
 	unsigned		amd_resume_bug:1; /* AMD remote wakeup quirk */
 	unsigned		can_do_streams:1; /* HC supports streams */
+	unsigned		cant_recv_wakeups:1;
+			/* wakeup requests from downstream aren't received */
 
 	unsigned int		irq;		/* irq allocated */
 	void __iomem		*regs;		/* device memory/io */