[Openchrome-devel] openchrome 0.6.0 regressions on VX900 laptop

[Bartosz]

Hi.
I have the same L740 laptop and under Windows XP it report 1366x768
resolution.

Do you know how to get dump of registers under Windows?
I would like to VGA or HDMI and check how registers are looks like.

Maybe Luc have some experience with dumping registers under Windows.

Best Regards
Bartosz

2017-03-18 23:37 GMT+01:00 Xavier Bachelot <xavier at bachelot.org>:

> Hi Kevin,
>
> On 18/03/2017 22:32, Kevin Brace wrote:
> > Hi Xavier,
> >
> > Sorry for missing the reply for several days, but I have been
> > thinking about this issue for the past few days.
>
> No worries.
>
> > I have several possible explanations as to why things are not
> > working. Of course, it is not proven so you will need to test it
> > yourself. Xavier, since you mentioned pitch, I noticed that when
> > reading the Xorg.0.log, I noticed that the screen resolution is 1368
> > x 768. I believe the correct resolution is 1366 x 768. I know that
> > sounds strange, but VIA EPIA-M830 user manual lists the panel index,
> > and it assigns 1366 x 768 for panel index 10. Yes, 1366 is a number
> > that is not dividable by 8, but for some reason, the flat panel
> > industry uses this odd resolution for some FPs.
>
> That doesn't surprise me that much, iirc the (now mostly defunct)
> Samsung NC20 I own used 1366x768 too. I'd really need to fix it someday...
>
> > You might be wondering why this causes the old code which allowed
> > IGA1 to work fine with 1366 x 768 flat panel, but not with IGA2. Due
> > to the way IBM developed VGA (and probably this goes back to EGA and
> > even Motorola MC6845 I suppose), when IGA1 horizontal display period
> > is set, the value being set has to be shifted by 3 bit positions (8
> > pixel boundary). IGA1 pretty much drags the original VGA way of
> > setting the horizontal display period since it is a superset of VGA,
> > but IGA2 is implemented without such restriction since it is a clean
> > sheet design. IGA2 horizontal resolution can be set at 1 pixel
> > boundary. Since you were using 1368 instead of 1366, this means that
> > all other display parameters get messed up like blank period and sync
> > period as well.
>
> Just gave it a try with 1366x768 instead of 1368x768, but that doesn't
> help. The screen is still distorted, not the same, but similarly. Also,
> the part of the screen displaying a picture is now bigger, it's covering
> half the height of the screen, rather than one third with 1368x768.
>
> > I know that the screen can easily get messed up if these numbers are
> > off even slightly, so this might be why you are seeing a distorted
> > picture with V2 and V3 patches I sent to you. That being said, you
> > said you are seeing a cursor with the V2 and V3 patches that
> > previously did not display.
>
> The only condition I was not sure there was a cursor is when using 0.6.0
> + panel id fix (1368x768) + via_regs_dump -w 3d5.99 0x11
> I just checked and the cursor is there too.
> Both v2 and v3 also have the cursor.
> Oh, and not sure I mentioned it, the cursor looks fine. it's not
> distorted in any way.
>
> > This probably means that not specifying IGA2 for LVDS1 was one of the
> > reason why the screen regression happened, but also 1366 vs. 1368
> > issue came into play, and I also speculate IGA2 itself is far more
> > sensitive to the display period being off by even 2 pixels.
> >
> Let's assume the Epia M830 manual is correct.
> I can't get my hands on the manual for this laptop to make sure of the
> expected resolution (assuming the manual specify it and is correct
> indeed) at the moment, I will need to dig deeper, I'm not even sure
> there was one in the first place. Can't find it on the net either, this
> is a noname computer, likely a reference design for VIA, who sent it to
> me for testing purposes back in the days.
> dmidecode says :
>         Manufacturer: iDOT Computers, Inc.
>         Product Name: L740
>
> Any other idea ?
>
> Regards,
> Xavier
>
>
> > Regards,
> >
> > Kevin Brace The OpenChrome Project maintainer / developer
> >
> >
> >> Sent: Thursday, March 16, 2017 at 11:17 AM From: "Xavier Bachelot"
> >> <xavier at bachelot.org> To: "Kevin Brace" <kevinbrace at gmx.com> Cc:
> >> openchrome-devel at lists.freedesktop.org Subject: Re:
> >> [Openchrome-devel] openchrome 0.6.0 regressions on VX900 laptop
> >>
> >> Hi Kevin,
> >>
> >> On 15/03/2017 23:33, Kevin Brace wrote:
> >>> Try this third version of the patch. I changed the FP power on /
> >>> off code to use software controlled method already proven with
> >>> CX700 / VX700 and VX800 chipsets.
> >>>
> >> No improvement over patch v2 with patch v3. I haven't collected
> >> neither log nor regs dump though.
> >>
> >> I started to poke at register manually after applying v2 the other
> >> day, but no luck. Is there any specific range of registers that are
> >> more likely than others to help ?
> >>
> >> Would a picture of the distorted screen, together with a picture of
> >> how it should look like, help ? I don't know how to describe the
> >> distortion, a picture is worth a thousand word :-) The display is
> >> compressed in the top third or half of the screen, and diagonally
> >> stretched to the right. The remaining bottom part of the screen
> >> seems like uninitialized memory. It seems like the framebuffer is
> >> using a different horizontal resolution than the display. Could it
> >> be something like wrong "pitch" ?
> >>
> >> Regards, Xavier
> >>
>
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