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authorFurquan Shaikh <furquan@google.com>2014-08-24 23:07:43 -0700
committerPatrick Georgi <pgeorgi@google.com>2015-03-19 23:24:23 +0100
commit5b1c328619ef9fcc533acf8cd1cf21ab4913b50b (patch)
tree83c68bd851c2ae37bb28cb80c70205a74dbfa419 /payloads
parentba87e6cc94f039abeabdf2d9d55eebcf23d77823 (diff)
downloadcoreboot-5b1c328619ef9fcc533acf8cd1cf21ab4913b50b.tar.xz
libpayload EHCI: Add memory barrier to EHCI driver
EHCI driver accesses mmio space using regular struct pointers. In order to avoid any CPU re-ordering, memory barrier is required in async_set_schedule, especially for arm64. Without the memory barrier, there seems to be re-ordering taking place which leads to USB errors with some flash drives as well as transfer errors in netboot. BUG=chrome-os-partner:31533 BRANCH=None TEST=With the memory barrier introduced, netboot for ryu completes transfer without any error and finishes within 6-7 seconds. Change-Id: Ib6d29dc79fd5722c27284478e8da316929e86bff Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: 561bdd746c4d4446ce0a6d21337d354625d85ddc Original-Change-Id: Ic05d47422312a1cddbebe3180f4f159853604440 Original-Signed-off-by: Furquan Shaikh <furquan@google.com> Original-Reviewed-on: https://chromium-review.googlesource.com/213917 Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org> Original-Tested-by: Furquan Shaikh <furquan@chromium.org> Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org> Reviewed-on: http://review.coreboot.org/8732 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Diffstat (limited to 'payloads')
-rw-r--r--payloads/libpayload/drivers/usb/ehci.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/payloads/libpayload/drivers/usb/ehci.c b/payloads/libpayload/drivers/usb/ehci.c
index b83712c463..7002623e49 100644
--- a/payloads/libpayload/drivers/usb/ehci.c
+++ b/payloads/libpayload/drivers/usb/ehci.c
@@ -30,6 +30,7 @@
//#define USB_DEBUG
#include <libpayload.h>
+#include <arch/barrier.h>
#include <arch/cache.h>
#include "ehci.h"
#include "ehci_private.h"
@@ -317,6 +318,14 @@ static int wait_for_tds(qtd_t *head)
static int ehci_set_async_schedule(ehci_t *ehcic, int enable)
{
+
+ /* Memory barrier to ensure that all memory accesses before we set the
+ * async schedule are complete. It was observed especially in the case of
+ * arm64, that netboot and usb stuff resulted in lots of errors possibly
+ * due to CPU reordering. Hence, enforcing strict CPU ordering.
+ */
+ mb();
+
/* Set async schedule status. */
if (enable)
ehcic->operation->usbcmd |= HC_OP_ASYNC_SCHED_EN;