On Mon, Feb 12, 2018 at 11:55 AM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> Mike Lothian reported that plugging in a USB-C device does not work
> properly in his Dell Alienware system. This system has Intel Alpine
> Ridge Thunderbolt controller providing USB-C functionality. In these
> systems the USB controller (xHCI) is hotplugged whenever a device is
> connected to the port using ACPI based hotplug.
>
> The ACPI description of the root port in question looks as follows:
>
> Device (RP01)
> {
> Name (_ADR, 0x001C0000)
>
> Device (PXSX)
> {
> Name (_ADR, 0x02)
>
> Method (_RMV, 0, NotSerialized)
> {
> // ...
> }
> }
>
> Here _ADR 0x02 means device 0, function 2 on the bus under root port
> (RP1) but that seems to be incorrect because device 0 is the upstream
> port of the Alpine Ridge PCIe switch and it does not have other
> functions than 0 (the bridge itself). When we get ACPI Notify() to the
> root port resulting from connecting a USB-C device, Linux tries to read
> PCI_VENDOR_ID from device 0, function 2 which of course always returns
> 0xffffffff because there is no such function and we never find the
> device.
>
> In Windows this works fine.
>
> Now, since we get ACPI Notify() to the root port and not to the PXSX
> device we should actually start our scan from there as well and not from
> the non-existent PXSX device so fix this by checking presence of the
> slot itself (function 0) if we fail to do that otherwise.
>
> While there use pci_bus_read_dev_vendor_id() in get_slot_status() which
> is the recommended way to read device and vendor ID of device on PCI bus.
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=198557
> Reported-by: Mike Lothian <mike@xxxxxxxxxxxxxx>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/pci/hotplug/acpiphp_glue.c | 23 ++++++++++++++++-------
> 1 file changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index e2198a2feeca..b45b375c0e6c 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -541,6 +541,7 @@ static unsigned int get_slot_status(struct acpiphp_slot *slot)
> {
> unsigned long long sta = 0;
> struct acpiphp_func *func;
> + u32 dvid;
>
> list_for_each_entry(func, &slot->funcs, sibling) {
> if (func->flags & FUNC_HAS_STA) {
> @@ -551,19 +552,27 @@ static unsigned int get_slot_status(struct acpiphp_slot *slot)
> if (ACPI_SUCCESS(status) && sta)
> break;
> } else {
> - u32 dvid;
> -
> - pci_bus_read_config_dword(slot->bus,
> - PCI_DEVFN(slot->device,
> - func->function),
> - PCI_VENDOR_ID, &dvid);
> - if (dvid != 0xffffffff) {
> + if (pci_bus_read_dev_vendor_id(slot->bus,
> + PCI_DEVFN(slot->device, func->function),
> + &dvid, 0)) {
> sta = ACPI_STA_ALL;
> break;
> }
> }
> }
>
> + if (!sta) {
> + /*
> + * Check for the slot itself since it may be that the
> + * ACPI slot is a device below PCIe upstream port so in
> + * that case it may not even be reachable yet.
> + */
> + if (pci_bus_read_dev_vendor_id(slot->bus,
> + PCI_DEVFN(slot->device, 0), &dvid, 0)) {
> + sta = ACPI_STA_ALL;
> + }
> + }
> +
> return (unsigned int)sta;
> }
>
> --
> 2.15.1
>
> --
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