Stefan Reinauer (stefan.reinauer@coreboot.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/2651
-gerrit
commit 9f939937defc6d2fbb8ea82850454995d9e85fd0 Author: Julius Werner jwerner@chromium.org Date: Fri Jan 11 16:25:52 2013 -0800
libpayload: Split EHCI bulk transfers on packet boundaries over qTDs
EHCI controllers see transfers as a queue of transfer descriptors (qTDs), each of which can represent an aligned area of up to 20KB. Each qTD is processed separately, which means that a single USB packet cannot span multiple qTDs.
While this should not be a problem according to the specification, some USB storage devices seem to get confused when a packet in the middle of a transfer is smaller than the maximum packet size (512 bytes) due to falling on a qTD boundary. This patch aligns the total transfer length per qTD to 512 bytes to avoid that problem (any excess bytes will simply roll over to the next qTD).
Change-Id: I0b5db07507699a3861b30c1a5ee774c45dda7fdd Signed-off-by: Julius Werner jwerner@chromium.org --- payloads/libpayload/drivers/usb/ehci.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/payloads/libpayload/drivers/usb/ehci.c b/payloads/libpayload/drivers/usb/ehci.c index d33fec5..972962c 100644 --- a/payloads/libpayload/drivers/usb/ehci.c +++ b/payloads/libpayload/drivers/usb/ehci.c @@ -241,6 +241,10 @@ static int fill_td(qtd_t *td, void* data, int datalen) } datalen -= 4096; total_len += 4096; + + /* end TD at a packet boundary if transfer not complete */ + if (page_no == 5) + total_len &= ~511; } } td->token |= total_len << QTD_TOTAL_LEN_SHIFT;