diff options
Diffstat (limited to 'drivers/usb/early/xhci-dbc.h')
| -rw-r--r-- | drivers/usb/early/xhci-dbc.h | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/drivers/usb/early/xhci-dbc.h b/drivers/usb/early/xhci-dbc.h index 673686eeddd7..6e2b7266a695 100644 --- a/drivers/usb/early/xhci-dbc.h +++ b/drivers/usb/early/xhci-dbc.h @@ -120,8 +120,22 @@ struct xdbc_ring { u32 cycle_state; }; -#define XDBC_EPID_OUT 2 -#define XDBC_EPID_IN 3 +/* + * These are the "Endpoint ID" (also known as "Context Index") values for the + * OUT Transfer Ring and the IN Transfer Ring of a Debug Capability Context data + * structure. + * According to the "eXtensible Host Controller Interface for Universal Serial + * Bus (xHCI)" specification, section "7.6.3.2 Endpoint Contexts and Transfer + * Rings", these should be 0 and 1, and those are the values AMD machines give + * you; but Intel machines seem to use the formula from section "4.5.1 Device + * Context Index", which is supposed to be used for the Device Context only. + * Luckily the values from Intel don't overlap with those from AMD, so we can + * just test for both. + */ +#define XDBC_EPID_OUT 0 +#define XDBC_EPID_IN 1 +#define XDBC_EPID_OUT_INTEL 2 +#define XDBC_EPID_IN_INTEL 3 struct xdbc_state { u16 vendor; |