ThinkWiki - User contributions [en]

Problem with DVI throughput

2005-06-18T20:55:00Z

69.138.185.170:

Information about the DVI throughput problem on port replicators and docks with Thinkpads from approximately 2000-2004.

==Problem description==

All Thinkpad port replicators and docking stations support a maximum resolution of 1280x1024 on the replicators/docks DVI port.
Resolutions above are not supported in standard drivers at all and lead to random screen corruption if used with modified or alternative drivers.

Random screen corruption means that approximately 1 out of 5 times you will have a lot ot flickering blue and green pixels (roughly gathered to vertical stripes) on your DVI driven display.

I also discovered the phenomena of an unsharp picture when having automatic picture expansion enabled on my 1600x1200px display. Switching this off recovers the picture quality.

It is not entirely clear so far if the screen corruption problems are a driver or hardware problem.

==Affected Models==

*ThinkPad {{A Series}}
*ThinkPad {{R Series}}
*ThinkPad {{T Series}}
*ThinkPad {{X Series}}
*all port replicators and docking stations for these models, namely

==Affected Operating Systems==

*Linux, all flavours
*Windows, all flavours

==Status==

IBM knows about this and has included this limitation into the specs of all these docking solutions.

It is possible to run higher resolutions on the DVI port. Linux supports this natively. With Windows you need to install an alternative driver for the ATI graphics card since the IBM driver doesn't support higher resolutions than 1280x1024 on DVI. Also one can do some registry hacking to make the higher resolutions available in the Presentation Manager.

However, on both displays still remains the phenoma of random screen corruption.

==Solutions==

===Linux===

Under Linux, you can in theory make use of higher resolutions. (This is currently limited by the unability of drivers to use the DVI port.) If screen corruption should occur, you can try fixing it by changing from X to the console and back. Doing this often helps.

===Windows===
The solution to the Windows driver problem can be found in patched ATI driver sets like [http://www.dna-drivers.nl/ DNA-ATI] or [http://www.omegadrivers.net OMEGA] drivers.

Another option is to download the latest drivers from www.ati.com and patch them with Patje's Mobility Modding tool found here http://www.driverheaven.net/patje/. The tool solves the problem indeed, but introduces the new problem, that you can't use resolutions of 1400x1050 px anymore, since this is a notebook only resolution which is not supported by the standard Catalyst drivers. All resolutions should work with version 5.6 Catalyst drivers.

The remaining problem with Windows is that IBMs practical Presentation Director utility still doesn't support the higher resolution.
This issue is solvable by doing some manual modifications to Presentation Directors registry entries. If you don't want to tweak your registry you can use multi-res (packaged with the OMEGA drivers) instead of Presentation Director.

If you want to use Presentation Director, follow this procedure:
* Add a profile with VGA output and set it to 1600x1200.
* Then you also add a profile with DVI output and set it to 1280x1024.
* After finishing the wizard you open regedit.
* Look for the Presentation directors key structure (HKEY_CURRENT_USER/Software/IBM/NPdirect/Data/Common/Presentation/Schemes) and
* copy the resolution value from the VGA profile to the DVI profile. (So if your VGA profiles name is VGAprof and the DVI profiles is DVIprof, you copy the Resolution keys value from HKEY_CURRENT_USER/Software/IBM/NPdirect/Data/Common/Presentation Schemes/VGAprof/01 to ....../DVIprof/01.)
* Close regedit (and eventually reboot) and restart Presentation Director.
* You should be have the wanted resolution in the properties of your DVI profile.

You can also have Presentation Director automatically call a batch file that calls mult-res application. The batch file will use multi-res to switch to one of the higher resolutions not supported by the Presentation Director.

Batch file example:
multires.exe /1920,1200,32,60 /exit

[[Category:Windows]]

Talk:Problem with DVI throughput

2005-06-18T20:52:47Z

69.138.185.170: /* No problmes here */

Here's some information I found:

Most DVI devices today use single-link DVI which supports a maximum bandwidth of 165 MHz [http://www.ddwg.org/dvi.html]. I suppose that ThinkPads provide a single-link DVI signal.

To calculate the bandwidth of your signal, in theory you just need to multiply the resolution with the vertical frequency. For example: 1600x1200 @ 85 Hz => 1600*1200*85 Hz = 163 MHz. This looks good, but it is outside the specs - because you need to take into account some extra time. CRTs need a so-called ''blanking time'' between the data for two display lines. This time is needed for something similar to a carriage return on a typewriter: The electron beam needs to be returned to the start of the next line. Additionally, some extra time is needed to transmit information about the border area around the real picture. About 25% of the bandwidth is used for these additional data. [http://graphics.tomshardware.com/graphic/20041129/tft_connection-04.html]

This means, that there is no specific ThinkPad problem with the throughput - you are just trying to transfer video data at a rate that is outside the specs of DVI. Maybe the DVI transmitter inside the ThinkPad even works at this data rate. But the DVI receiver inside the monitor might be "overclocked".

TFTs don't really need extra time. So there is a chance of writing a display driver with a reduced blanking time. This might explain, why some people were successful with other drivers.

The effective maximum resolution for single link DVI should be around 1600x1200 @ 65 Hz, or @ 60 Hz to be on the sure side. Has anyone solved his problems by lowering the vertical frequency?

--[[User:137.226.40.2|137.226.40.2]] 14:23, 1 Mar 2005 (CET)

== No problem on T41p ==

I have a T41p with 1400x1040 LCD and a Samsung SyncMaster 213T connected through the Port Replicator II with DVI<br>
After some windows registry hacks I can run the Samsung in 1600x1200 in single, clone display and extend display mode.<br>
Linux requires no such hacks and will happily run at 1600x1200

The picture through DVI is perfect with either desktop applications or running DVD video.

----
This is good news.
Do you run Linux in DualHead, MergedFB or CloneMode?
In Windows you have a clear video overlay all the time (like after every boot)?
Which drivers are you using in Linux and Windows, please list the with version numbers.

[[User:217.230.177.126|217.230.177.126]] 01:31, 10 Mar 2005 (CET)
----

==Question about DVI/LCD switching on T4x / Radeon M9 / Linux==
Has anyone been able to successfully switch back and forth between the LCD output and the Port Replicator II DVI output on Linux? How do you do it? My problem is described below:

[[http://forums.gentoo.org/viewtopic-t-320973-highlight-.html]]

== No problems here ==

I installed the new catalyst drivers 5.6 using Patje's Mobility Moddingand it works for all resolutions. My laptop runs at 1400x1060 and my dvi screen at 1920x1200.
No problems that I can tell. The omega drivers (based on older catalyst drivers) blue screened my windows xp on boot.

Talk:Problem with DVI throughput

2005-06-18T20:52:24Z

69.138.185.170: No problmes here

Here's some information I found:

Most DVI devices today use single-link DVI which supports a maximum bandwidth of 165 MHz [http://www.ddwg.org/dvi.html]. I suppose that ThinkPads provide a single-link DVI signal.

To calculate the bandwidth of your signal, in theory you just need to multiply the resolution with the vertical frequency. For example: 1600x1200 @ 85 Hz => 1600*1200*85 Hz = 163 MHz. This looks good, but it is outside the specs - because you need to take into account some extra time. CRTs need a so-called ''blanking time'' between the data for two display lines. This time is needed for something similar to a carriage return on a typewriter: The electron beam needs to be returned to the start of the next line. Additionally, some extra time is needed to transmit information about the border area around the real picture. About 25% of the bandwidth is used for these additional data. [http://graphics.tomshardware.com/graphic/20041129/tft_connection-04.html]

This means, that there is no specific ThinkPad problem with the throughput - you are just trying to transfer video data at a rate that is outside the specs of DVI. Maybe the DVI transmitter inside the ThinkPad even works at this data rate. But the DVI receiver inside the monitor might be "overclocked".

TFTs don't really need extra time. So there is a chance of writing a display driver with a reduced blanking time. This might explain, why some people were successful with other drivers.

The effective maximum resolution for single link DVI should be around 1600x1200 @ 65 Hz, or @ 60 Hz to be on the sure side. Has anyone solved his problems by lowering the vertical frequency?

--[[User:137.226.40.2|137.226.40.2]] 14:23, 1 Mar 2005 (CET)

== No problem on T41p ==

I have a T41p with 1400x1040 LCD and a Samsung SyncMaster 213T connected through the Port Replicator II with DVI<br>
After some windows registry hacks I can run the Samsung in 1600x1200 in single, clone display and extend display mode.<br>
Linux requires no such hacks and will happily run at 1600x1200

The picture through DVI is perfect with either desktop applications or running DVD video.

----
This is good news.
Do you run Linux in DualHead, MergedFB or CloneMode?
In Windows you have a clear video overlay all the time (like after every boot)?
Which drivers are you using in Linux and Windows, please list the with version numbers.

[[User:217.230.177.126|217.230.177.126]] 01:31, 10 Mar 2005 (CET)
----

==Question about DVI/LCD switching on T4x / Radeon M9 / Linux==
Has anyone been able to successfully switch back and forth between the LCD output and the Port Replicator II DVI output on Linux? How do you do it? My problem is described below:

[[http://forums.gentoo.org/viewtopic-t-320973-highlight-.html]]

== No problmes here ==

I installed the new catalyst drivers 5.6 using Patje's Mobility Moddingand it works for all resolutions. My laptop runs at 1400x1060 and my dvi screen at 1920x1200.
No problems that I can tell. The omega drivers (based on older catalyst drivers) blue screened my windows xp on boot.

Problem with DVI throughput

2005-06-18T16:41:08Z

69.138.185.170:

Information about the DVI throughput problem on port replicators and docks with Thinkpads from approximately 2000-2004.

==Problem description==

All Thinkpad port replicators and docking stations support a maximum resolution of 1280x1024 on the replicators/docks DVI port.
Resolutions above are not supported in standard drivers at all and lead to random screen corruption if used with modified or alternative drivers.

Random screen corruption means that approximately 1 out of 5 times you will have a lot ot flickering blue and green pixels (roughly gathered to vertical stripes) on your DVI driven display.

I also discovered the phenomena of an unsharp picture when having automatic picture expansion enabled on my 1600x1200px display. Switching this off recovers the picture quality.

It is not entirely clear so far if the screen corruption problems are a driver or hardware problem.

==Affected Models==

*ThinkPad {{A Series}}
*ThinkPad {{R Series}}
*ThinkPad {{T Series}}
*ThinkPad {{X Series}}
*all port replicators and docking stations for these models, namely

==Affected Operating Systems==

*Linux, all flavours
*Windows, all flavours

==Status==

IBM knows about this and has included this limitation into the specs of all these docking solutions.

It is possible to run higher resolutions on the DVI port. Linux supports this natively. With Windows you need to install an alternative driver for the ATI graphics card since the IBM driver doesn't support higher resolutions than 1280x1024 on DVI. Also one can do some registry hacking to make the higher resolutions available in the Presentation Manager.

However, on both displays still remains the phenoma of random screen corruption.

==Solutions==

===Linux===

Under Linux, you can in theory make use of higher resolutions. (This is currently limited by the unability of drivers to use the DVI port.) If screen corruption should occur, you can try fixing it by changing from X to the console and back. Doing this often helps.

===Windows===
The solution to the Windows driver problem can be found in patched ATI driver sets like [http://www.dna-drivers.nl/ DNA-ATI] or [http://www.omegadrivers.net OMEGA] drivers.
Another option is to download the latest drivers from www.ati.com and patch them with Patje's Mobility Modding tool found here http://www.driverheaven.net/patje/.

Also, Dax Kelson posted [http://mailman.linux-thinkpad.org/pipermail/linux-thinkpad/2004-June/018167.html this mail] in the [[mailinglists#Linux-Thinkpad_Mailinglist | Linux-Thinkpad Mailinglist]]. The tool he recommends solves the problem indeed, but introduces the new problem, that you can't use resolutions of 1400x1050 px anymore, since this is a notebook only resolution which is not supported by the standard Catalyst drivers.

The remaining problem with Windows is that IBMs practical Presentation Director utility still doesn't support the higher resolution.
This issue is solvable by doing some manual modifications to Presentation Directors registry entries. If you don't want to tweak your registry you can use multi-res (packaged with the OMEGA drivers) instead of Presentation Director.

If you want to use Presentation Director, follow this procedure:
* Add a profile with VGA output and set it to 1600x1200.
* Then you also add a profile with DVI output and set it to 1280x1024.
* After finishing the wizard you open regedit.
* Look for the Presentation directors key structure (HKEY_CURRENT_USER/Software/IBM/NPdirect/Data/Common/Presentation/Schemes) and
* copy the resolution value from the VGA profile to the DVI profile. (So if your VGA profiles name is VGAprof and the DVI profiles is DVIprof, you copy the Resolution keys value from HKEY_CURRENT_USER/Software/IBM/NPdirect/Data/Common/Presentation Schemes/VGAprof/01 to ....../DVIprof/01.)
* Close regedit (and eventually reboot) and restart Presentation Director.
* You should be have the wanted resolution in the properties of your DVI profile.

You can also have Presentation Director automatically call a batch file that calls mult-res application. The batch file will use multi-res to switch to one of the higher resolutions not supported by the Presentation Director.

Batch file example:
multires.exe /1920,1200,32,60 /exit

[[Category:Windows]]

Problem with DVI throughput

2005-06-14T20:22:22Z

69.138.185.170:

Information about the DVI throughput problem on port replicators and docks with Thinkpads from approximately 2000-2004.

==Problem description==

All Thinkpad port replicators and docking stations support a maximum resolution of 1280x1024 on the replicators/docks DVI port.
Resolutions above are not supported in standard drivers at all and lead to random screen corruption if used with modified or alternative drivers.

Random screen corruption means that approximately 1 out of 5 times you will have a lot ot flickering blue and green pixels (roughly gathered to vertical stripes) on your DVI driven display.

I also discovered the phenomena of an unsharp picture when having automatic picture expansion enabled on my 1600x1200px display. Switching this off recovers the picture quality.

It is not entirely clear so far if the screen corruption problems are a driver or hardware problem.

==Affected Models==

*ThinkPad {{A Series}}
*ThinkPad {{R Series}}
*ThinkPad {{T Series}}
*ThinkPad {{X Series}}
*all port replicators and docking stations for these models, namely

==Affected Operating Systems==

*Linux, all flavours
*Windows, all flavours

==Status==

IBM knows about this and has included this limitation into the specs of all these docking solutions.

It is possible to run higher resolutions on the DVI port. Linux supports this natively. With Windows you need to install an alternative driver for the ATI graphics card since the IBM driver doesn't support higher resolutions than 1280x1024 on DVI. Also one can do some registry hacking to make the higher resolutions available in the Presentation Manager.

However, on both displays still remains the phenoma of random screen corruption.

==Solutions==

===Linux===

Under Linux, you can in theory make use of higher resolutions. (This is currently limited by the unability of drivers to use the DVI port.) If screen corruption should occur, you can try fixing it by changing from X to the console and back. Doing this often helps.

===Windows===
The solution to the Windows driver problem can be found in patched ATI driver sets like [http://www.dna-drivers.nl/ DNA-ATI] or [http://www.omegadrivers.net OMEGA] drivers.

Also, Dax Kelson posted [http://mailman.linux-thinkpad.org/pipermail/linux-thinkpad/2004-June/018167.html this mail] in the [[mailinglists#Linux-Thinkpad_Mailinglist | Linux-Thinkpad Mailinglist]]. The tool he recommends solves the problem indeed, but introduces the new problem, that you can't use resolutions of 1400x1050 px anymore, since this is a notebook only resolution which is not supported by the standard Catalyst drivers.

The remaining problem with Windows is that IBMs practical Presentation Director utility still doesn't support the higher resolution.
This issue is solvable by doing some manual modifications to Presentation Directors registry entries. If you don't want to tweak your registry you can use multi-res (packaged with the OMEGA drivers) instead of Presentation Director.

If you want to use Presentation Director, follow this procedure:
* Add a profile with VGA output and set it to 1600x1200.
* Then you also add a profile with DVI output and set it to 1280x1024.
* After finishing the wizard you open regedit.
* Look for the Presentation directors key structure (HKEY_CURRENT_USER/Software/IBM/NPdirect/Data/Common/Presentation/Schemes) and
* copy the resolution value from the VGA profile to the DVI profile. (So if your VGA profiles name is VGAprof and the DVI profiles is DVIprof, you copy the Resolution keys value from HKEY_CURRENT_USER/Software/IBM/NPdirect/Data/Common/Presentation Schemes/VGAprof/01 to ....../DVIprof/01.)
* Close regedit (and eventually reboot) and restart Presentation Director.
* You should be have the wanted resolution in the properties of your DVI profile.

You can also have Presentation Director automatically call a batch file that calls mult-res application. The batch file will use multi-res to switch to one of the higher resolutions not supported by the Presentation Director.

Batch file example:
multires.exe /1920,1200,32,60 /exit

[[Category:Windows]]