diff options
| -rw-r--r-- | drivers/usb/host/xhci.h | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 439767d242fa..71588e4db0e3 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1748,11 +1748,20 @@ static inline void xhci_write_64(struct xhci_hcd *xhci, } -/* Link TRB chain should always be set on 0.95 hosts, and AMD 0.96 ISOC rings */ +/* + * Reportedly, some chapters of v0.95 spec said that Link TRB always has its chain bit set. + * Other chapters and later specs say that it should only be set if the link is inside a TD + * which continues from the end of one segment to the next segment. + * + * Some 0.95 hardware was found to misbehave if any link TRB doesn't have the chain bit set. + * + * 0.96 hardware from AMD and NEC was found to ignore unchained isochronous link TRBs when + * "resynchronizing the pipe" after a Missed Service Error. + */ static inline bool xhci_link_chain_quirk(struct xhci_hcd *xhci, enum xhci_ring_type type) { return (xhci->quirks & XHCI_LINK_TRB_QUIRK) || - (type == TYPE_ISOC && (xhci->quirks & XHCI_AMD_0x96_HOST)); + (type == TYPE_ISOC && (xhci->quirks & (XHCI_AMD_0x96_HOST | XHCI_NEC_HOST))); } /* xHCI debugging */ |