Stefan Reinauer (stefan.reina...@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 <jwer...@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 <jwer...@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;
--
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