Commit be982038 authored May 08, 2014 by Sarah Sharp Committed by Greg Kroah-Hartman May 20, 2014

xhci: Report max device limit when Enable Slot command fails.



xHCI host controllers may only support a limited number of device slot
IDs, which is usually far less than the theoretical maximum number of
devices (255) that the USB specifications advertise.  This is
frustrating to consumers that expect to be able to plug in a large
number of devices.

Add a print statement when the Enable Slot command fails to show how
many devices the host supports.  We can't change hardware manufacturer's
design decisions, but hopefully we can save customers a little bit of
time trying to debug why their host mysteriously fails when too many
devices are plugged in.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Reported-by: Amund Hov <Amund.Hov@silabs.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent a62445ae

drivers/usb/host/xhci.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -3696,6 +3696,9 @@ int xhci_alloc_dev(struct usb_hcd hcd, struct usb_device udev)

		if (!xhci->slot_id) {
		xhci_err(xhci, "Error while assigning device slot ID\n");
		xhci_err(xhci, "Max number of devices this xHCI host supports is %u.\n",
		HCS_MAX_SLOTS(
		readl(&xhci->cap_regs->hcs_params1)));
		return 0;
		}

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