From 69eea7c01af0ce095aa7618eadae72e86f6eebbe Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Fri, 11 Jan 2013 16:25:52 -0800 Subject: [PATCH] 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 Reviewed-on: http://review.coreboot.org/2651 Tested-by: build bot (Jenkins) Reviewed-by: Patrick Georgi Reviewed-by: Paul Menzel Reviewed-by: Ronald G. Minnich --- 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 d33fec57b6..972962cf51 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; -- 2.11.4.GIT