[Bug 16033] New: [Randr12] DPI calculation ludicrously incorrect

[Bug 16033] New: [Randr12] DPI calculation ludicrously incorrect

[bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ]

http://bugs.freedesktop.org/show_bug.cgi?id=16033

           Summary: [Randr12] DPI calculation ludicrously incorrect
           Product: xorg
           Version: git
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/nouveau
        AssignedTo: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
        ReportedBy: chalserogers-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
         QAContact: xorg-team-go0+a7rfsptAfugRpC6u6w@public.gmane.org


Created an attachment (id=16646)
 --> (http://bugs.freedesktop.org/attachment.cgi?id=16646)
Xorg log, showing DPI set to (230, 254)

It seems that the DPI calculation is using the Virtual line to calculate the
DPI.  Since this is substantially larger than my laptop's screen resolution
this results in a DPI value slightly under double the true DPI!

This may well not be a nouveau bug; I've had a grep through the source and it
seems that nouveau is just setting the DPI received from the server.


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[Bug 16033] [Randr12] DPI calculation ludicrously incorrect

[bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ]

http://bugs.freedesktop.org/show_bug.cgi?id=16033


Frans Pop <elendil-EIBgga6/0yRmR6Xm/wNWPw@public.gmane.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |elendil-EIBgga6/0yRmR6Xm/wNWPw@public.gmane.org




--- Comment #1 from Frans Pop <elendil-EIBgga6/0yRmR6Xm/wNWPw@public.gmane.org>  2008-08-15 14:48:40 PST ---
I'm seeing the same issue on my new laptop (HP 1510p running Debian Lenny).
Initially DPI was getting set to (96, 96), which is too low for my laptop's LCD
screen. Apparently because the laptop's display does not provide size info.

From the Xorg log:
(II) intel(0): Output VGA disconnected
(II) intel(0): Output LVDS connected
(II) intel(0): Output TV disconnected
(II) intel(0): Output LVDS using initial mode 1280x800
(II) intel(0): Monitoring connected displays enabled
(II) intel(0): detected 512 kB GTT.
(II) intel(0): detected 7676 kB stolen memory.
(==) intel(0): video overlay key set to 0x101fe
(==) intel(0): Will not try to enable page flipping
(==) intel(0): Triple buffering disabled
(==) intel(0): Intel XvMC decoder disabled
(==) intel(0): Using gamma correction (1.0, 1.0, 1.0)
(==) intel(0): DPI set to (96, 96)


I had already been playing with a second monitor connected for which I needed
the "Virtual" option. Using info from the Debian wiki I added the correct
display size setting for LVDS, after which my xorg.conf had:

Section "Device"
        Identifier      "Intel GM965 Video Controller"
        Option          "Monitor-LVDS"  "Internal Panel"
        Option          "Monitor-VGA"   "External VGA Monitor"
EndSection

Section "Monitor"
        Identifier      "Internal Panel"
        DisplaySize     261 163         # 10.2x6.3"
EndSection

Section "Monitor"
        Identifier      "External VGA Monitor"
EndSection

Section "Screen"
        Identifier      "Default Screen"
        Monitor         "Internal Panel"

        Subsection "Display"
                Virtual         3000 2000
        EndSubSection
EndSection

After restarting the X server this resulted in:
(II) intel(0): Output VGA disconnected
(II) intel(0): Output LVDS connected
(II) intel(0): Output TV disconnected
(II) intel(0): Output LVDS using initial mode 1280x800
(II) intel(0): Monitoring connected displays enabled
(II) intel(0): detected 512 kB GTT.
(II) intel(0): detected 7676 kB stolen memory.
(==) intel(0): video overlay key set to 0x101fe
(==) intel(0): Will not try to enable page flipping
(==) intel(0): Triple buffering disabled
(==) intel(0): Intel XvMC decoder disabled
(==) intel(0): Using gamma correction (1.0, 1.0, 1.0)
(**) intel(0): Display dimensions: (261, 163) mm
(**) intel(0): DPI set to (291, 311)

Given that only the LVDS is connected the DPI should be (125, 126) based on the
LVDS mode and the display dimensions. The actual DPI is way too high and can be
shown to be calculated from the (dummy) Virtual mode (for example: 3000 / (261
/ 10 / 2.54) = 291).

Even if multiple displays are connected the Virtual setting is not a useful
value as it only defines the _maximum_ area that can be used by combining
monitors and not the _actual_ area.

Note that if I also add the external VGA monitor in the Screen section, the DPI
will default to (96, 96) again. But if I list them in reverse order (external
VGA first and LVDS second), I get the above values again.
Seems like the display dimensions of the last monitor are used, regardless of
what is actually connected.

Cheers,
FJP


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[Bug 16033] [Randr12] DPI calculation ludicrously incorrect

[bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ]

http://bugs.freedesktop.org/show_bug.cgi?id=16033





--- Comment #2 from Pekka Paalanen <pq-X3B1VOXEql0@public.gmane.org>  2009-09-23 05:12:14 PST ---
Does this problem still occur with the latest released xorg-server?

If it does, maybe this bug should be re-targeted to xorg-server?


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[Bug 16033] [Randr12] DPI calculation ludicrously incorrect

[bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ]

http://bugs.freedesktop.org/show_bug.cgi?id=16033


Elvis Pranskevichus <elprans-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |elprans-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org




--- Comment #3 from Elvis Pranskevichus <elprans-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>  2010-01-11 11:16:08 PST ---
I can confirm this happening on xorg-server-1.7.4 on my system.  I use external
monitor in a randr setup and the physical dimensions reported in xdpyinfo are
totally wrong:

dimensions: 4000x1600 pixels (331x207 millimeters)
resolution: 307x196 dots per inch

I have DisplaySize set for both monitors and apparently the server takes only
the first one.

Now, I've hit this trying to remedy a regression from xorg-server-1.6. 
Previously, physical dimensions were detected correctly and a correct DPI was
set.  Now (with 1.7.4) it just uses 96x96.  xrandr reports correct dimensions
in all cases.

Oh, and I'm on xf86-video-intel, so this is almost definitely not
nouveau-specific.


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[Bug 16033] [Randr12] DPI calculation ludicrously incorrect

[bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ]

https://bugs.freedesktop.org/show_bug.cgi?id=16033

Marcin Slusarz <marcin.slusarz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|Driver/nouveau              |Server/general
         AssignedTo|nouveau-PD4FTy7X32lNgt0PjOBp93rCq3LdnpKM@public.gmane.org |xorg-team-go0+a7rfsptAfugRpC6u6w@public.gmane.org
                   |rg                          |

--- Comment #4 from Marcin Slusarz <marcin.slusarz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2010-07-23 16:37:32 PDT ---
probably not nouveau bug, changing component to Server/general

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