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Old 11-10-10, 07:38 AM   #1
thecapsaicinkid
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Default Is this a bug? GPU scaling option results in a different refresh

Code:
xrandr -r 60 
nvidia-settings -q RefreshRate | grep -o "[0-9][0-9].*Hz"
With GPU scaling enabled this would report 50.0Hz (DynamicTwinView is disabled)

This seems like a bug to me, the driver seems to be scaling to my 'nvidia-auto-select' mode (1920x1080_50) regardless of what the current refresh is. Hardware scaling seems to be enabled by default so I can see most people with PAL screens will just lose the ability to use 60Hz output at all which causes lots of problems playing back 60fps content.

I'd assume the desired behaviour is to look at the resolution of nvidia-select (your screen's native) and try and locate a mode which matches this plus the current refresh. So in my case, something running at say 480p60 would scale to 1080p60 and not 1080p50. Am I missing something here? I don't remember seeing an option to choose the desired scaling resolution.

My mode pool

Code:
 --- Modes in ModePool for SONY TV (DFP-0) ---
 "nvidia-auto-select" : 1920 x 1080 @  50.0 Hz  (from: EDID)
 "1920x1080"          : 1920 x 1080 @  50.0 Hz  (from: EDID)
 "1920x1080_50"       : 1920 x 1080 @  50.0 Hz  (from: EDID)
 "1920x1080_60"       : 1920 x 1080 @ 59.94/60 Hz (CEA-861B Format 16) (from: EDID)
 "1920x1080_60i"      : 1920 x 1080 @  60.1 Hz Interlace  (from: EDID)
 "1920x1080_60i_0"    : 1920 x 1080 @ 59.94/60 Hz (CEA-861B Format 5) (from: EDID)
 "1920x1080_50i"      : 1920 x 1080 @ 50 Hz Interlace (CEA-861B Format 20) (from: EDID)
 "1280x720"           : 1280 x  720 @  60.0 Hz  (from: EDID)
 "1280x720_60"        : 1280 x  720 @  60.0 Hz  (from: EDID)
 "1280x720_60_0"      : 1280 x  720 @ 59.94/60 Hz (CEA-861B Format 4) (from: EDID)
 "1280x720_50"        : 1280 x  720 @  50.0 Hz  (from: EDID)
 "720x576"            :  720 x  576 @  50.0 Hz  (from: EDID)
 "720x576_50"         :  720 x  576 @  50.0 Hz  (from: EDID)
 "720x576_50i"        : (1440)x 576 @ 50 Hz Interlace (CEA-861B Format 22) (from: EDID)
 "720x480"            :  720 x  480 @  59.9 Hz  (from: EDID)
 "720x480_60"         :  720 x  480 @  59.9 Hz  (from: EDID)
 "720x480_60i"        : (1440)x 480 @ 59.94/60 Hz Interlace (CEA-861B Format 7) (from: EDID)
 "640x480"            :  640 x  480 @ 59.94/60 Hz Interlace (CEA-861B Format 1) (from: EDID)
 "640x480_60"         :  640 x  480 @ 59.94/60 Hz Interlace (CEA-861B Format 1) (from: EDID)
 --- End of ModePool for SONY TV (DFP-0): ---
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Old 11-10-10, 10:18 AM   #2
AaronP
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Default Re: Is this a bug? GPU scaling option results in a different refresh

I know it's confusing, but that's what the GPU scaling option does: it drives the panel at its native mode (including its native refresh rate) and scales the requested mode to that. In particular, that means that the requested mode's refresh rate is ignored and only its dimensions are used.

We've considered adding code to do like you suggest: try to find an EDID supported mode with a matching refresh rate and switch to that, but it hasn't been implemented yet. For now I would suggest just disabling the scaling option.
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Old 11-11-10, 07:53 AM   #3
thecapsaicinkid
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Default Re: Is this a bug? GPU scaling option results in a different refresh

A clean install of the nvidia driver on the latest Ubuntu seems to end up with gpu scaling enabled, it's not enabled in xorg.conf so nvidia-settings must turn it on when run on boot.

Is it possible for package maintainers to set scaling to disabled on install of the nvidia driver/nvidia-settings?
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Old 11-11-10, 12:20 PM   #4
AaronP
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Default Re: Is this a bug? GPU scaling option results in a different refresh

Quote:
Originally Posted by thecapsaicinkid View Post
A clean install of the nvidia driver on the latest Ubuntu seems to end up with gpu scaling enabled, it's not enabled in xorg.conf so nvidia-settings must turn it on when run on boot.

Is it possible for package maintainers to set scaling to disabled on install of the nvidia driver/nvidia-settings?
It's enabled by default. You can disable it in xorg.conf by setting an option:
Code:
   Option "FlatPanelProperties" "Scaling = Native"
It's enabled by default because most flat panels have really poor scaling hardware and most people prefer the GPU's scaling.
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