diff options
| author | Julius Werner <jwerner@chromium.org> | 2013-01-11 16:25:52 -0800 |
|---|---|---|
| committer | Ronald G. Minnich <rminnich@gmail.com> | 2013-03-13 23:08:11 +0100 |
| commit | 69eea7c01af0ce095aa7618eadae72e86f6eebbe (patch) | |
| tree | aa8da537c37121dc0817462e5a78417ede0d6728 /payloads/libpayload | |
| parent | 716375dd3ee8ec695c38b2ab25e714a0cc116fb0 (diff) | |
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>
Reviewed-on: http://review.coreboot.org/2651
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Diffstat (limited to 'payloads/libpayload')
| -rw-r--r-- | payloads/libpayload/drivers/usb/ehci.c | 4 |
1 files changed, 4 insertions, 0 deletions
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; |