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From: cinap_lenrek@felloff.net
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Subject: Re: [9front] aux/vga -p intermittent edid reporting
Reply-To: 9front@9front.org
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> It looks to me like the edid fetching is not very stable in igfx.c, so
> might be giving some wrong values, or misapplying the values provided.
> I've concluded this because I've used the returned edid values in
> /lib/vgadb, and it produces a scrambled (illegible) screen.

that is not possible. the edid structure is checksummed. so even if
theres a problem on transmission it is unlikely to contain conconsitent
values.

it is more likely that theres some problem with your specific controller
version that hasnt been addressed (wrong clock calculation, wrong
reference frequency used). you have to read the documentation
from 01.org and verify.

> I have no idea how to do that.  I see auxctl and auxdat in
> /sys/src/cmd/aux/vga/igfx.c so assume that's where I should start, and
> refer to the manuals to figure things out.

yeah, pretty much.

also, you have to be more specific what "garbled" means. the controller
might just work fine producing a clean signal (the image is stable),
but theres some issue with the video memory mapping in the GTT so it
renders garbage?

> #
> # Apple MacBook Pro early 2011
> #
> mbp2011=1280x800
>	clock=72.5
>	shb=1328 ehb=1360 ht=1423
>	vrs=803 vre=809 vt=846
>	hsync=- vsync=-

you should add lcd=1 attribute here too.

--
cinap