diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2012-10-01 10:32:15 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-10-22 11:10:24 -0700 |
| commit | 6a41b4d3fe8cd4cc95181516fc6fba7b1747a27c (patch) | |
| tree | 2b4dc08f94a67985f595d157c399774cee4e661a /drivers/usb/host/ohci-hcd.c | |
| parent | c44b225077bb1fb25ed5cd5c4f226897b91bedd4 (diff) | |
OHCI: implement new semantics for URB_ISO_ASAP
This patch (as1614) updates the isochronous scheduling in ohci-hcd to
match the new semantics for URB_ISO_ASAP. Testing revealed a hardware
bug in the way my OHCI controller handles expired isochronous TDs;
consequently the patch tries hard to avoid creating them (unlike the
ehci-hcd and uhci-hcd drivers).
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/host/ohci-hcd.c')
| -rw-r--r-- | drivers/usb/host/ohci-hcd.c | 36 |
1 files changed, 32 insertions, 4 deletions
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c index 4a1d64d9233..cfc1da30667 100644 --- a/drivers/usb/host/ohci-hcd.c +++ b/drivers/usb/host/ohci-hcd.c @@ -231,13 +231,41 @@ static int ohci_urb_enqueue ( frame &= ~(ed->interval - 1); frame |= ed->branch; urb->start_frame = frame; + } + } else if (ed->type == PIPE_ISOCHRONOUS) { + u16 next = ohci_frame_no(ohci) + 2; + u16 frame = ed->last_iso + ed->interval; + + /* Behind the scheduling threshold? */ + if (unlikely(tick_before(frame, next))) { - /* yes, only URB_ISO_ASAP is supported, and - * urb->start_frame is never used as input. + /* USB_ISO_ASAP: Round up to the first available slot */ + if (urb->transfer_flags & URB_ISO_ASAP) + frame += (next - frame + ed->interval - 1) & + -ed->interval; + + /* + * Not ASAP: Use the next slot in the stream. If + * the entire URB falls before the threshold, fail. */ + else if (tick_before(frame + ed->interval * + (urb->number_of_packets - 1), next)) { + retval = -EXDEV; + usb_hcd_unlink_urb_from_ep(hcd, urb); + goto fail; + } + + /* + * Some OHCI hardware doesn't handle late TDs + * correctly. After retiring them it proceeds to + * the next ED instead of the next TD. Therefore + * we have to omit the late TDs entirely. + */ + urb_priv->td_cnt = DIV_ROUND_UP(next - frame, + ed->interval); } - } else if (ed->type == PIPE_ISOCHRONOUS) - urb->start_frame = ed->last_iso + ed->interval; + urb->start_frame = frame; + } /* fill the TDs and link them to the ed; and * enable that part of the schedule, if needed |