diff options
Diffstat (limited to 'drivers/usb/host/xhci-ring.c')
| -rw-r--r-- | drivers/usb/host/xhci-ring.c | 41 |
1 files changed, 40 insertions, 1 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index cc59632..396f8d2 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -3144,6 +3144,42 @@ static unsigned int xhci_get_burst_count(struct xhci_hcd *xhci, return roundup(total_packet_count, max_burst + 1) - 1; } +/* + * Returns the number of packets in the last "burst" of packets. This field is + * valid for all speeds of devices. USB 2.0 devices can only do one "burst", so + * the last burst packet count is equal to the total number of packets in the + * TD. SuperSpeed endpoints can have up to 3 bursts. All but the last burst + * must contain (bMaxBurst + 1) number of packets, but the last burst can + * contain 1 to (bMaxBurst + 1) packets. + */ +static unsigned int xhci_get_last_burst_packet_count(struct xhci_hcd *xhci, + struct usb_device *udev, + struct urb *urb, unsigned int total_packet_count) +{ + unsigned int max_burst; + unsigned int residue; + + if (xhci->hci_version < 0x100) + return 0; + + switch (udev->speed) { + case USB_SPEED_SUPER: + /* bMaxBurst is zero based: 0 means 1 packet per burst */ + max_burst = urb->ep->ss_ep_comp.bMaxBurst; + residue = total_packet_count % (max_burst + 1); + /* If residue is zero, the last burst contains (max_burst + 1) + * number of packets, but the TLBPC field is zero-based. + */ + if (residue == 0) + return max_burst; + return residue - 1; + default: + if (total_packet_count == 0) + return 0; + return total_packet_count - 1; + } +} + /* This is for isoc transfer */ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags, struct urb *urb, int slot_id, unsigned int ep_index) @@ -3186,6 +3222,7 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags, for (i = 0; i < num_tds; i++) { unsigned int total_packet_count; unsigned int burst_count; + unsigned int residue; first_trb = true; running_total = 0; @@ -3197,6 +3234,8 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags, le16_to_cpu(urb->ep->desc.wMaxPacketSize)); burst_count = xhci_get_burst_count(xhci, urb->dev, urb, total_packet_count); + residue = xhci_get_last_burst_packet_count(xhci, + urb->dev, urb, total_packet_count); trbs_per_td = count_isoc_trbs_needed(xhci, urb, i); @@ -3210,7 +3249,7 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags, for (j = 0; j < trbs_per_td; j++) { u32 remainder = 0; - field = TRB_TBC(burst_count); + field = TRB_TBC(burst_count) | TRB_TLBPC(residue); if (first_trb) { /* Queue the isoc TRB */ |