diff options
| author | Furquan Shaikh <furquan@google.com> | 2014-08-24 23:07:43 -0700 |
|---|---|---|
| committer | Patrick Georgi <pgeorgi@google.com> | 2015-03-19 23:24:23 +0100 |
| commit | 5b1c328619ef9fcc533acf8cd1cf21ab4913b50b (patch) | |
| tree | 83c68bd851c2ae37bb28cb80c70205a74dbfa419 /payloads/libpayload/drivers | |
| parent | ba87e6cc94f039abeabdf2d9d55eebcf23d77823 (diff) | |
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/libpayload/drivers')
| -rw-r--r-- | payloads/libpayload/drivers/usb/ehci.c | 9 |
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; |