wrong dpi after update

[Alex Deucher]

On Jan 2, 2008 4:23 PM, Bernd Schubert <bernd-schubert at gmx.de> wrote:
> Alex Deucher wrote:
>
> > On Dec 31, 2007 8:59 PM, Bernd Schubert <bernd-schubert at gmx.de> wrote:
> >> Hi,
> >>
> >> I'm using Debian Sid on my desktop system, but I did the last update some
> >> weeks ago. After updating today several parts of X got updated and now
> >> something goes wrong with display-size detection and hence the display
> >> dpi is wrong (as are all font sizes).
> >>
> >> (II) RADEON(0): Supported additional Video Mode:
> >> (II) RADEON(0): clock: 162.0 MHz   Image Size:  367 x 275 mm
> >>
> >> bernd at bathl ~>xrandr
> >> Screen 0: minimum 320 x 200, current 1600 x 1200, maximum 1600 x 1200
> >> VGA-0 disconnected (normal left inverted right x axis y axis)
> >> DVI-0 connected 1600x1200+0+0 (normal left inverted right x axis y axis)
> >> 367mm x 275mm
> >>    1600x1200      60.0*+   59.9
> >>
> >> But:
> >>
> >> (II) RADEON(0): EDID Version: 1.3
> >> (II) RADEON(0): Digital Display Input
> >> (II) RADEON(0): Max H-Image Size [cm]: horiz.: 41  vert.: 31
> >> (II) RADEON(0): Gamma: 2.20
> >>
> >> 410x310 mm is the correct display size, but somehow by default 367x275 mm
> >> are used. And even though EDID provides correct information?
> >> Setting the correct value with "xrandr --fbdev 410x310" does work, but in
> >> the past this did work automatically?
> >
> > Both numbers are coming from the edid.  We use the size from the
> > detailed timing block (367 x 275 mm).
>
> So my monitor provides 2 different edid information and unfortunately the
> wrong one is used? Well, I guess I can't modify the firmware of my
> display :(
> What about a database of broken displays?

well, most (all) edids have the max image size in cm and the then the
detailed timing blocks can specify the image size in mm.  The xserver
uses the size from the detailed timing block.  Normally the sizes are
pretty close (well, as close as mm -> cm can be).  For your monitor
that does not appear to be the case.

>
> Also, I think randr for some reason seems to overwrite given xorg.conf
> display sizes
>
> after xf86InitialConfiguration
> (**) RADEON(0): Display dimensions: (410, 310) mm
> (**) RADEON(0): DPI set to (99, 98)
> (II) Loading sub module "fb"
> (II) LoadModule: "fb"
> (II) Loading /usr/lib/xorg/modules//libfb.so
>
> And then later on
>
> (II) GLX: Initialized DRI GL provider for screen 0
> (II) RADEON(0): Setting screen physical size to 367 x 275
>
> I think the first is taken from my xorg.conf display section. Bug or
> feature?
>

Ignore the log.  look at the output of xrandr and xdpyinfo.  You can
hard code the display size using the DisplaySize option in a monitor
section linked to the output in question.
DisplaySize     410 310

Alex