[PATCH resent] Option to use DPI calculated from EDID

[Michal Suchanek]

Hello,

On 4 January 2016 at 00:26, Guillem Jover <guillem at hadrons.org> wrote:
> Hi!
>
> On Mon, 2011-10-31 at 13:16:21 +0100, Michal Suchanek wrote:
>> It adds back functionality lost a few years ago which makes X
>> needlessly hard to use on devices that report correct DPI and aren't
>> 96 DPI which is the value unconditionally set since commit fff00d
>
> This affected me recently too when setting up a new laptop, quite
> annoying. Here's a quick review.

This seems to be no longer the case on recent Debian systems:

xdpyinfo | grep resol
  resolution:    100x100 dots per inch

Screen 0: minimum 320 x 200, current 2560 x 1440, maximum 8192 x 8192
DisplayPort-0 connected primary 2560x1440+0+0 (normal left inverted
right x axis y axis) 597mm x 336mm

I am not sure where this comes from since the actual DPI seems to be
more like 109 rather than 100:

2560*25.4/597
108.91792
1440*25.4/336
108.85714

xdpyinfo | grep resol
  resolution:    94x94 dots per inch

Screen 0: minimum 320 x 200, current 2400 x 1600, maximum 8192 x 8192
DVI-I-1 connected primary 1200x1600+1200+0 (normal left inverted right
x axis y axis) 324mm x 432mm
   1200x1600     59.96*+
HDMI-1 connected 1200x1600+0+0 left (normal left inverted right x axis
y axis) 408mm x 306mm
   1600x1200     60.00*+

Here 94 DPI is precise for the first display and the second 100 DPI
display is not taken into account:

1200*25.4/306
99.60784
1600*25.4/408
99.60784
1200*25.4/324
94.07407
1600*25.4/432
94.07407

Linux 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1+deb8u4
xserver-xorg-core             2:1.17.3-2
xserver-xorg-video-radeon     1:7.5.0-1+b1
xserver-xorg-video-nouveau    1:1.0.12-1

Thanks

Michal