diff options
| author | Nico Huber <nico.h@gmx.de> | 2020-07-18 20:49:38 +0200 |
|---|---|---|
| committer | Nico Huber <nico.h@gmx.de> | 2020-07-21 15:14:48 +0000 |
| commit | 3c7888bf293ad6c5d879dd0ef1ddc1a6bad7470c (patch) | |
| tree | ef13a75e5fe06712ec4fd19b3ca81fffa9b164fb /payloads/libpayload/drivers | |
| 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 'payloads/libpayload/drivers')
| -rw-r--r-- | payloads/libpayload/drivers/usb/xhci_private.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/payloads/libpayload/drivers/usb/xhci_private.h b/payloads/libpayload/drivers/usb/xhci_private.h index 8e11937ac5..b4c8825dc6 100644 --- a/payloads/libpayload/drivers/usb/xhci_private.h +++ b/payloads/libpayload/drivers/usb/xhci_private.h @@ -363,7 +363,7 @@ typedef struct erst_entry { #define CAP_CSZ_LEN 1 #define CAP_MASK(tok) MASK(CAP_##tok##_START, CAP_##tok##_LEN) -#define CAP_GET(tok, cap) (((cap)->CAP_##tok##_FIELD & CAP_MASK(tok)) \ +#define CAP_GET(tok, cap) ((read32(&(cap)->CAP_##tok##_FIELD) & CAP_MASK(tok)) \ >> CAP_##tok##_START) #define CTXSIZE(xhci) (CAP_GET(CSZ, (xhci)->capreg) ? 64 : 32) |