I suggest a subject like this:
PCI: Prevent xHCI driver from claiming AMD Nolan USB3 DRD device
On Tue, Oct 28, 2014 at 5:54 AM, Huang Rui <ray.huang@xxxxxxx> wrote:
> The AMD Nolan (NL) SoC contains a DesignWare USB3 Dual-Role Device that can
> be operated either as a USB Host or a USB Device. In the AMD NL platform,
> this device ([1022:7912]) has a class code of PCI_CLASS_SERIAL_USB_XHCI
> (0x0c0330), which means the xhci driver will claim it.
>
> But the dwc3 driver is a more specific driver for this device, and we'd
> prefer to use it instead of xhci. To prevent xhci from claiming the
> device, change the class code to 0x0c03fe, which the PCI r3.0 spec defines
> as "USB device (not host controller)". The dwc3 driver can then claim it
> based on its Vendor and Device ID.
>
> Suggested-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Please merge along with the rest of your series.
> Cc: Jason Chang <jason.chang@xxxxxxx>
> Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
> ---
> drivers/pci/quirks.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 90acb32..1152bef 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -379,6 +379,26 @@ static void quirk_ati_exploding_mce(struct pci_dev *dev)
> DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_RS100, quirk_ati_exploding_mce);
>
> /*
> + * In the AMD NL platform, this device ([1022:7912]) has a class code of
> + * PCI_CLASS_SERIAL_USB_XHCI (0x0c0330), which means the xhci driver will
> + * claim it.
> + * But the dwc3 driver is a more specific driver for this device, and we'd
> + * prefer to use it instead of xhci. To prevent xhci from claiming the
> + * device, change the class code to 0x0c03fe, which the PCI r3.0 spec
> + * defines as "USB device (not host controller)". The dwc3 driver can then
> + * claim it based on its Vendor and Device ID.
> + */
> +static void quirk_amd_nl_class(struct pci_dev *pdev)
> +{
> + /*
> + * Use 'USB Device' (0x0x03fe) instead of PCI header provided
> + */
> + pdev->class = 0x0c03fe;
> +}
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_NL_USB,
> + quirk_amd_nl_class);
> +
> +/*
> * Let's make the southbridge information explicit instead
> * of having to worry about people probing the ACPI areas,
> * for example.. (Yes, it happens, and if you read the wrong
> --
> 1.9.1
>
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