Nico Huber has posted comments on this change. ( https://review.coreboot.org/28935 )
Change subject: nb/i945: Check if IGD is enabled before R/W to dev(0, 2) ......................................................................
Patch Set 1:
(3 comments)
I do not have a datasheet, but, if I'm not wrong, using r2 on vendor bios of d945gclf (supported board), it seems making a test before writing : MEMORY[0xFED14F08] |= 0x6000u; MEMORY[0xFED14F0A] |= 0x6000u; MEMORY[0xFED14F0C] |= 0x6000u;
What does it test? CAPID[38] maybe? or DEVEN?
https://review.coreboot.org/#/c/28935/1/src/northbridge/intel/i945/raminit.c File src/northbridge/intel/i945/raminit.c:
https://review.coreboot.org/#/c/28935/1/src/northbridge/intel/i945/raminit.c... PS1, Line 2151:
here by default, IGD is "enabled" even if it is not (case we use an external GPU for example)
Again, AFAICS, this code runs before the external GPU decision is made. It can't be disabled yet.
https://review.coreboot.org/#/c/28935/1/src/northbridge/intel/i945/raminit.c... PS1, Line 2306: : : :
as we have : "int integrated_graphics = 1;" […]
But it shows us what to do if.
https://review.coreboot.org/#/c/28935/1/src/northbridge/intel/i945/raminit.c... PS1, Line 2764: pci_read_config8(PCI_DEV(0, 0x0, 0), DEVEN) & : (DEVEN_D2F0 | DEVEN_D2F1) Always true?