diff options
| author | Anton Staaf <robotboy@chromium.org> | 2015-02-11 15:34:52 -0800 |
|---|---|---|
| committer | ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> | 2015-02-17 18:19:14 +0000 |
| commit | 6c83a4d3a560c84e4f7030d3dcad583e92781f8b (patch) | |
| tree | b575a9c5b03d838f11be5731b746e84a61edead9 | |
| parent | 2e6bee5642be6d863c8a87b8bf60643b99c64f62 (diff) | |
| download | chrome-ec-6c83a4d3a560c84e4f7030d3dcad583e92781f8b.tar.gz | |
USB: fix memcpy_to_usbram
A change to the toolchain or environment surfaced an issue where the writes to
packet RAM were being split into two 16-bit writes. This was interacting
poorly with the AHB2APB bridge.
Marking the packet RAM destination pointer volatile forces the compiler to use
full 32-bit writes.
Signed-off-by: Anton Staaf <robotboy@chromium.org>
BRANCH=None
BUG=None
TEST=make buildall -j
Check that Ryu's console is accessible over USB
Change-Id: I0c3db08c704389a627570b90ef97bce81ab553fa
Reviewed-on: https://chromium-review.googlesource.com/248840
Trybot-Ready: Anton Staaf <robotboy@chromium.org>
Tested-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Vic Yang <victoryang@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Queue: Anton Staaf <robotboy@chromium.org>
| -rw-r--r-- | chip/stm32/usb.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/chip/stm32/usb.c b/chip/stm32/usb.c index 631dc8a19d..ff71b4e582 100644 --- a/chip/stm32/usb.c +++ b/chip/stm32/usb.c @@ -346,9 +346,15 @@ int usb_is_enabled(void) void *memcpy_to_usbram(void *dest, const void *src, size_t n) { - int i; - uint8_t *s = (uint8_t *) src; - usb_uint *d = (usb_uint *)((uintptr_t) dest & ~1); + /* + * The d pointer needs to be volatile to prevent GCC from possibly + * breaking writes to the USB packet RAM into multiple 16-bit writes, + * which, due to the way the AHB2APB bridge works would clobber what + * we write with 32-bit extensions of the 16-bit writes. + */ + int i; + uint8_t *s = (uint8_t *) src; + usb_uint volatile *d = (usb_uint volatile *)((uintptr_t) dest & ~1); if ((((uintptr_t) dest) & 1) && n) { /* |