# gentoo-sources-2.6.36, radeon KMS and underscan [solved]

## Tariella

I recently updated from gentoo-sources-2.6.34 to 2.6.36, KMS with radeon enabled (radeon 3200 cipset). My screen is a 1920x1080 LCD TV. 

Booting the new kernel gives me no full screen output (like I had with 2.6.34) but a broad black border around the console/output.

Since my kernel config stayed the same, I guess the issue lies in the kernel version.

Is this a bug or are there some new options I must use to get the output resolution with KMS rigt?

If this is a bug is it gentoo-sources related?

Anyone else having this issue?Last edited by Tariella on Wed Nov 03, 2010 3:59 pm; edited 1 time in total

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## kingfame_147

Could you please post your xorg.conf, your Xorg.0.log, a dmesg output and the output of 

```
xrandr --verbose
```

.

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## Tariella

I'm using xorg-server-1.8.2 without config files except a xorg.conf.d/01-keyboard.conf file for my german keyboard.

Here is my dmesg: http://pastebin.com/2DK1Ahib

and my Xorg.0.log: http://pastebin.com/4r1mGN91

xrandr --verbose gives: http://pastebin.com/tSmiFaEG

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## chithanh

In the new kernel, the radeon driver defaults to enable underscan. This is to compensate for overscan setting in the TV. Unfortunately, the driver has no way of determining whether the TV has overscan enabled. So it uses a heuristic based on connector type.

To check the underscan setting, run from X:

```
$ xrandr --prop
```

To enable or disable underscan, use

```
$ xrandr --output <outputname> --set underscan <on|off>
```

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## Tariella

Great! It works!   :Very Happy: 

I never knew there was something like underscan. As soon as I knew what to search for google gave me lots of results.   :Embarassed: 

I guess I'll have to wait a while until there will be a kernel option for switching underscan off at boot time.

Thanks a lot and sorry for bothering you!

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## kingfame_147

You should be able to set that setting in the xorg.conf

I think you can use all the xrandr options also in the xorg.conf. I'll post later if I'm at my linux machine. Have to work now :/

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## Tariella

Thanks, that would help until there is a boot option for the kernel line in grub.  :Smile: 

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## kingfame_147

Sorry I was busy yesterday.

I'll take a look after work and post it here.

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## kingfame_147

Hi,

you should be able to do something like:

```

Section "Device"

    Identifier  "Radeon HD 5700 Series"

    Driver      "radeon"

    VendorName  "ATI Technologies Inc Juniper"

    Option      "Randr12"           "true"

    Option      "underscan"        "true"

EndSection

```

ofc. you have to change the Identifier.

I'm not 100% sure if all xrandr options can be set with the xorg.conf, but it's worth a try :)

Regards,

fame

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