Hi,
On 06.11.2016 11:25, Patrick Rudolph wrote:
Am 06.11.2016 um 09:33 schrieb Charlotte Plusplus:
Also, in romstage I am not sure of : /* Disable unused devices (board specific) */ RCBA32(FD) = 0x1ee51fe3;
You can dump the value stock lenovo bios sets at boot using the inteltool, that ships in coreboot's utils folder.
The W520 is a bit different from a t420 and I think it may not be the same. How do I compute this number?
The function disable (FD) register is publicly documented [1, p.407]. As most times, the documentation isn't comprehensive. There are some more bits explained in src/southbridge/intel/bd82x6x/pch.h:442, bit 27 is for the xHCI controller, bit 26 should always be set. Bits 5:12 btw. don't apply to your PCH, they used to be for UHCI controllers. The only bit in the number above I can't figure out is bit 28.
The FD register is actually configured dynamically based on the device- tree (see src/southbridge/intel/bd82x6x/pch.c). So you don't need an ugly constant there. You should only make sure that PCH_DISABLE_ALWAYS is set. Some boards also disable the PCI bridge early so that this one doesn't get probed (just an optimization). I'm not sure, why disabling the bridge in the devicetree wouldn't suffice.
Nico
[1] http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/6-chi...