diff options
| author | Kevin O'Connor <kevin@koconnor.net> | 2010-09-08 11:00:25 +0000 |
|---|---|---|
| committer | Patrick Georgi <patrick.georgi@coresystems.de> | 2010-09-08 11:00:25 +0000 |
| commit | c3c9b01efb50c691bacc4a9acc7abf69d5640eae (patch) | |
| tree | 9cd80d2ff5680d6bebf2f3fd701ecc29ebb237a1 /src/southbridge/via/vt8237r/vt8237r_early_smbus.c | |
| parent | a4c0a1d6e6669736e101ada54b81d529f7c84cde (diff) | |
Code must not access the smbus registers before the RTC power well is
ready (PSON gating). Some boards boot faster than this power well
stabilization, and thus see bad data when accessing the smbus
registers.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Acked-by: Peter Stuge <peter@stuge.se>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5788 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
Diffstat (limited to 'src/southbridge/via/vt8237r/vt8237r_early_smbus.c')
| -rw-r--r-- | src/southbridge/via/vt8237r/vt8237r_early_smbus.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/southbridge/via/vt8237r/vt8237r_early_smbus.c b/src/southbridge/via/vt8237r/vt8237r_early_smbus.c index 357ad819c0..4372a4a89d 100644 --- a/src/southbridge/via/vt8237r/vt8237r_early_smbus.c +++ b/src/southbridge/via/vt8237r/vt8237r_early_smbus.c @@ -132,12 +132,15 @@ u8 smbus_read_byte(u8 dimm, u8 offset) return val; } +#define PSONREADY_TIMEOUT 0x7fffffff + /** * Enable the SMBus on VT8237R-based systems. */ void enable_smbus(void) { device_t dev; + int loops; /* Power management controller */ dev = pci_locate_device(PCI_ID(PCI_VENDOR_ID_VIA, @@ -150,6 +153,12 @@ void enable_smbus(void) die("Power management controller not found\n"); } + /* Make sure the RTC power well is up before touching smbus. */ + loops = 0; + while (!(pci_read_config8(dev, VT8237R_PSON) & (1<<6)) + && loops < PSONREADY_TIMEOUT) + ++loops; + /* * 7 = SMBus Clock from RTC 32.768KHz * 5 = Internal PLL reset from susp |