From: Dan Williams <dan.j.williams@xxxxxxxxx> Add a command line switch for disabling ehci port switchover. Useful for working around / debugging xhci incompatibilities where ehci operation is available. Reference: http://marc.info/?l=linux-usb&m=138920063001509&w=2 Cc: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx> Cc: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Cc: Holger Hans Peter Freyther <holger@xxxxxxxxxxxxxxxx> Suggested-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> --- Documentation/kernel-parameters.txt | 3 +++ drivers/usb/host/pci-quirks.c | 15 +++++++++++++-- 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 4384217..fc3403114 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2251,6 +2251,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. nox2apic [X86-64,APIC] Do not enable x2APIC mode. + noxhci_port_switch + [USB] Use EHCI instead of XHCI where available + cpu0_hotplug [X86] Turn on CPU0 hotplug feature when CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. Some features depend on CPU0. Known dependencies are: diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c index 00661d3..38bfe3d 100644 --- a/drivers/usb/host/pci-quirks.c +++ b/drivers/usb/host/pci-quirks.c @@ -823,6 +823,15 @@ static int handshake(void __iomem *ptr, u32 mask, u32 done, return -ETIMEDOUT; } +static int noxhci_port_switch; + +static int __init noxhci_port_switch_setup(char *str) +{ + noxhci_port_switch = 1; + return 0; +} +early_param("noxhci_port_switch", noxhci_port_switch_setup); + /* * Intel's Panther Point chipset has two host controllers (EHCI and xHCI) that * share some number of ports. These ports can be switched between either @@ -860,8 +869,7 @@ void usb_enable_intel_xhci_ports(struct pci_dev *xhci_pdev) return; /* Don't switchover the ports if the user hasn't compiled the xHCI - * driver. Otherwise they will see "dead" USB ports that don't power - * the devices. + * driver or has explicitly disabled switchover */ if (!IS_ENABLED(CONFIG_USB_XHCI_HCD)) { dev_warn(&xhci_pdev->dev, @@ -871,6 +879,9 @@ void usb_enable_intel_xhci_ports(struct pci_dev *xhci_pdev) "USB 3.0 devices will work at USB 2.0 speeds.\n"); usb_disable_xhci_ports(xhci_pdev); return; + } else if (noxhci_port_switch) { + usb_disable_xhci_ports(xhci_pdev); + return; } /* Read USB3PRM, the USB 3.0 Port Routing Mask Register -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
