Change in coreboot[master]: nb/i945: Check if IGD is enabled before R/W to dev(0, 2)

[Nico Huber (Code Review)]

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)
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Patch Set 1:
> > I don't see a way IGD could be disabled at this stage. But what about
> > SKUs that don't have it at all? are there any (on supported boards)?
>
> 1 - In case we use an external GPU, the IGD is disabled at
> arly_init.c (line #686).

Which is run after raminit.
> (BTW: line +949 should be commented)

It doesn't work without that line. You probably mean 950 should
be implemented for the desktop version. Please, go ahead.
> 2 - there some desktop's version that do not have IGD at all.

That's why I was asking. Are the DEVEN bits hard-wired to 0 for them?
> 3 - at function "sdram_power_management", we set integrated_graphics
> = 1 and use it for test in raminit.c line #2305 .... this do not
> make sense.

It documents for the human reader that it should only be executed
when integrated graphics are present (or maybe only when enabled;
that's not clear). This can be useful, for instance, when somebody
wants to implement it for system without IGD.