fbdev video modes

Investigation into how Linux on the PS3 might lead to homebrew development.

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ouasse
Posts: 80
Joined: Mon Jul 30, 2007 5:58 am
Location: Paris, France

fbdev video modes

Post by ouasse »

Hi everybody,

I can't get correct standard HD resolutions using the ps3 framebuffer device. I have two screens (a HD Ready Sony 32" TV and a IIyama 24" WUXGA flat screen), and the problem is the same whatever the screen I use.

"normal" 720p or 1080p modes have black borders around the screen. These black borders can be removed using the "-f" flag when calling ps3videomode. Unfortunately, full screen modes can't fully display on my screens : some kind of upscaling occurs, and about 5-10% of each screen border pixels are hidden.

Only VESA modes are correctly displayed, even though the WXGA mode is only 1280x768 with left and right black borders instead of 1366x768 in 16:9 format. But at least, no upscaling is done and the full screen is displayed.

I have tried to change the screen modes in linux's ps3fb.c file, changing the dotclocks to reduce the upscaling. This only results in undisplayable modes, or worse, kernel panics.

Do you people here have the same problems with your screen setups ? Is it due to some hypervisor restriction, or is there a way to display real 720p and 1080p modes ?

of course, these modes are correctly displayed on both screens when in GameOS.

thank you all for your help.
jonathan
Posts: 23
Joined: Fri Sep 21, 2007 12:18 pm
Location: Tasmania, Australia

Post by jonathan »

It is quite likely that your screens are actually not displaying the 5-10% of missing pixels - it's a common problem, and tends to not be detectable in general within the GameOS or HD movies.

Some screens have a "dot for dot" or similar setting which can, in some circumstances, help get full screen resolutions appearing correctly.
jimparis
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Joined: Fri Jun 10, 2005 4:21 am
Location: Boston

Post by jimparis »

You can't change the modes at this time, unfortunately.
See http://ozlabs.org/pipermail/cbe-oss-dev ... 04249.html for more info.
ouasse
Posts: 80
Joined: Mon Jul 30, 2007 5:58 am
Location: Paris, France

Post by ouasse »

jonathan wrote:It is quite likely that your screens are actually not displaying the 5-10% of missing pixels - it's a common problem, and tends to not be detectable in general within the GameOS or HD movies.
This is definitely not the case. All 720p / 1080i / 1080p screen modes are fully displayed in GameOS, on both screens (indeed the HD ready screen supports 1080p even though it's a WXGA display).
jimparis wrote:You can't change the modes at this time, unfortunately.
See http://ozlabs.org/pipermail/cbe-oss-dev ... 04249.html for more info.
The message you are quoting was about WSXGA+ modes (1680x1050), which are not supported at all by hypervisor. They don't talk about upscaling problems in standard HD modes. But this helps me understand now, why I can't change the screen modes in the Linux kernel source.
jonathan
Posts: 23
Joined: Fri Sep 21, 2007 12:18 pm
Location: Tasmania, Australia

Post by jonathan »

ouasse wrote:
jonathan wrote:It is quite likely that your screens are actually not displaying the 5-10% of missing pixels - it's a common problem, and tends to not be detectable in general within the GameOS or HD movies.
This is definitely not the case. All 720p / 1080i / 1080p screen modes are fully displayed in GameOS, on both screens (indeed the HD ready screen supports 1080p even though it's a WXGA display).
A simple test - get either the Pixel Junk Monsters or Racing demos and see if you can scale the game screen larger than the visible area of your display.
jimparis
Posts: 1145
Joined: Fri Jun 10, 2005 4:21 am
Location: Boston

Post by jimparis »

Actually Pixeljunk Monsters lets you scale the screen above 100% so it's not a good test.

If you run it at 1080p and view an image like this: http://jim.sh/~jim/tmp/1080test.png
then you should be able to tell pretty quickly whether you're viewing full pixels (it has a white border).
ouasse
Posts: 80
Joined: Mon Jul 30, 2007 5:58 am
Location: Paris, France

Post by ouasse »

jonathan wrote:It is quite likely that your screens are actually not displaying the 5-10% of missing pixels - it's a common problem, and tends to not be detectable in general within the GameOS or HD movies.
Actually you were right. I have copied the sample picture from jimparis to a USB stick, and indeed, I can't see the full picture in 1080p mode in GameOS.

The full picture can be displayed in WUXGA mode (1920x1200), which is the native resolution of my monitor.

I really don't understand why VESA modes are working perfectly, while HD modes have these missing pixels problems.
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