Re: [9front] aux/vga -p intermittent edid reporting

[unobe@cpan.org]

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Quoth cinap_lenrek@felloff.net:
> > But back to the main issue: is edid supposed to be consistently
> > reported, or is this expected?
> 
> no, this is not expected. this hints at some issue with the i2c
> controller code that is supposed to read the edid over the aux
> channel.
> 

Thanks cinap.

> the fix would be to fix that code so it read edid consistently.

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.  I see things like:

	/* hack: slow down a bit */

in /sys/src/cmd/aux/vga/igfx.c:/^dpauxio .

> on some intel cards, the i2c stuff doesnt work at all. in this
> case, you can copy the monitor information into vgadb and tell
> it to use that info directly, skipping the i2c part.

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.

cpu% tail /lib/vgadb
	lcd=1

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

cpu% cat /dev/vgactl
type igfx
size 1280x800x32 x8r8g8b8
tilt none
hwgc soft
hwaccel off
hwblank on
addr p 0x90000000 v 0xffffff0090000000 size 0x4000000
softscreen on
cpu% aux/vga -m mbp2011 -l 1280x800
aux/vga: main: mbp2011@1280x800 not in /lib/vgadb
cpu% aux/vga -m mbp2011 -l 1280x800
aux/vga: main: mbp2011@1280x800 not in /lib/vgadb
cpu% ""
	 cpu% aux/vga -m mbp2011 -l 1280x800
aux/vga: main: mbp2011@1280x800 not in /lib/vgadb
cpu% ""
	 cpu% aux/vga -m mbp2011 -l 1280x800
aux/vga: main: mbp2011@1280x800 not in /lib/vgadb
cpu% ""
	 cpu% aux/vga -m mbp2011 -l 1280x800
aux/vga: main: mbp2011@1280x800 not in /lib/vgadb
cpu% ""
	 cpu% aux/vga -m mbp2011 -l 1280x800
aux/vga: main: mbp2011@1280x800 not in /lib/vgadb
cpu% ""
	 cpu% aux/vga -m mbp2011 -l 1280x800
cpu% ss

As seen above, when the info is finally loaded from /lib/vgadb (1 in
19 odds, or so), there is no error from aux/vga.  Ss is just a
screenshot command:
cpu% cat /bin/ss
#!/bin/rc
cat /dev/screen | topng > /tmp/screenshot.png

It does not reflect the visual scrambing of the screen: the screenshot
looks as my screen *should* look, but does not.

Regardless, I've read enough of the aux/vga/igfx.c code to realize I
need to learn more before I try to address the issues I'm
experiencing.

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