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author | Nico Huber <nico.h@gmx.de> | 2020-07-18 20:49:38 +0200 |
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committer | Nico Huber <nico.h@gmx.de> | 2020-07-21 15:14:48 +0000 |
commit | 3c7888bf293ad6c5d879dd0ef1ddc1a6bad7470c (patch) | |
tree | ef13a75e5fe06712ec4fd19b3ca81fffa9b164fb /util/spdtool | |
parent | 767467dc67f4eb3c6b24e7cd6b548d0bdc0c2658 (diff) |
libpayload/xhci: Try harder to read 32-bit caps at once
With commit 287cf6c7d1 (lp/drivers/usb: Work around QEMU XHCI
register issue) we restructured our capability register accesses
because the compiler used the wrong access size. While we do use
only 32-bit types now, a compiler may still try to be clever and
optimize things in unexpected ways. So we add an explicit read32()
now.
For instance for the 8-bit MaxPorts field, in the most significant
bits of `capreg + 4`, our read + mask + shift
((cap)->hciparams1 & 0xff000000) >> 24
was turned into a single 8-bit read instruction by GCC on x86:
31: 0f b6 52 07 movzbl 0x7(%edx),%edx
Change-Id: I76accd0ef718e70ca46807eb06a9177c3afd99f1
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43575
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Diffstat (limited to 'util/spdtool')
0 files changed, 0 insertions, 0 deletions