How to refresh the list of outputs detected by xrandr?

[Hacksign]

emm ....
sorry about the title.
I forgot to change it as I do a' reply to list' operation ;(
Just read the history email ~~ thanks ~

On 11/19/2015 09:27 PM, Chris Wilson wrote:
> On Thu, Nov 19, 2015 at 02:19:25PM +0100, Łukasz Maśko wrote:
>> Hello.
>> I have a Dell E7250 laptop. I'm using it with docking stations with external
>> monitors connected. I have one dock at home and another one at work. The
>> monitors connected to them differ, both in models and connectors (and
>> therefore are recognized as different xrandr outputs).
>>
>> At home it looks like this:
>> $ xrandr
>> Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
>> eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y
>> axis) 276mm x 156mm
>>     1920x1080     60.02*+  48.03
>>     1400x1050     59.98
>>     1280x1024     60.02
>>     1280x960      60.00
>>     1024x768      60.00
>>     800x600       60.32    56.25
>>     640x480       59.94
>> DP1 disconnected (normal left inverted right x axis y axis)
>> DP1-1 disconnected (normal left inverted right x axis y axis)
>> DP1-2 disconnected (normal left inverted right x axis y axis)
>> DP1-3 connected (normal left inverted right x axis y axis)
>>     1440x900      59.89 +
>>     1280x1024     75.02    60.02
>>     1280x960      60.00
>>     1152x864      75.00
>>     1152x720      59.97
>>     1024x768      75.08    60.00
>>     832x624       74.55
>>     800x600       75.00    60.32    56.25
>>     848x480       60.00
>>     640x480       75.00    60.00    59.94
>>     720x400       70.08
>> DP2 disconnected (normal left inverted right x axis y axis)
>> HDMI1 disconnected (normal left inverted right x axis y axis)
>> HDMI2 disconnected (normal left inverted right x axis y axis)
>> VIRTUAL1 disconnected (normal left inverted right x axis y axis)
>>
>> while at work like this:
>> $ xrandr
>> Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
>> eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y
>> axis) 276mm x 156mm
>>     1920x1080     60.02*+  48.03
>>     1400x1050     59.98
>>     1280x1024     60.02
>>     1280x960      60.00
>>     1024x768      60.00
>>     800x600       60.32    56.25
>>     640x480       59.94
>> DP1 disconnected (normal left inverted right x axis y axis)
>> DP1-1 connected (normal left inverted right x axis y axis)
>>     1920x1080     60.00 +  50.00    59.94
>>     1600x1200     60.00
>>     1680x1050     59.88
>>     1280x1024     60.02
>>     1440x900      59.90
>>     1280x960      60.00
>>     1280x800      59.91
>>     1280x720      60.00    50.00    59.94
>>     1024x768      60.00
>>     800x600       60.32    56.25
>>     720x576       50.00
>>     720x480       60.00    59.94
>>     640x480       60.00    59.94
>> DP1-2 disconnected (normal left inverted right x axis y axis)
>> DP1-3 disconnected (normal left inverted right x axis y axis)
>> DP2 disconnected (normal left inverted right x axis y axis)
>> HDMI1 disconnected (normal left inverted right x axis y axis)
>> HDMI2 disconnected (normal left inverted right x axis y axis)
>> VIRTUAL1 disconnected (normal left inverted right x axis y axis)
>>
>>
>> The problem is, that if I suspend my laptop while it is connected to one of
>> the docking stations, it remembers the layout of available monitors and when I
>> dock it onto the other station and resume, it still shows me the old list of
>> outputs and modes. I need to undock it while running and dock it again to make
>> it notify the change in outputs.
>>
>> Is there a software way to force xrandr to refresh its state and notify the
>> change in connected devices?
> The kernel is supposed to send a hotplug notification on resume that
> should result in the list being updated.
> -Chris
>