unstable refresh rate

unstable refresh rate

[James]

I have a Gigabyte GeForce 1050 connected by DVI to a monitor (1920x1200 
resolution @ 59.9502 Hz) and a TV via HDMI (3840x2160 @30 Hz).
The problem is the TV used  to work at 59.9685 Hz but then it started 
showing "No signal" on the TV.
I was changing settings trying to get it to work again and I happened to 
change it to 30Hz and it worked.
The specs are here:
https://www.gigabyte.com/Graphics-Card/GV-N1050OC-2GD/sp#sp
 >Digital max resolution: 7680x4320
I should be ok resolution wise.
Could it be a poor cable?
kernel: 5.0.0-23-generic

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Re: unstable refresh rate

[Ilia Mirkin]

Hi James,

I semi-recently added support for HDMI 2.0 (in 4.20+, so you're good),
which is why you got 60Hz in the first place. In order for the high
rates to work, something called "scrambling" must be enabled. This is
done by 2-party agreement between the sink and the source. The sink
will inform the source that it's about to use scrambling (by writing
to the SCDC register on the display over i2c).

In my personal experiments, on a LG C6 series TV, I found that while
EDID works while the TV is off, the SCDC write does not. So you can
actually "turn on" the display on the computer while the TV itself is
off, and the scrambling setting will not have been propagated. Then
when you turn the TV on, it doesn't work. In order to remedy this, you
need to disable the display linux-side, and re-enable it.

The indicator for this sort of issue would be something about SCDC
reads/writes failing in dmesg -- do you see anything of the sort?
(Something like "Failure to write SCDC_TMDS_CONFIG")

If not, it's probably something else. But this seems like a likely candidate.

On Tue, Aug 6, 2019 at 12:14 PM James <bjlockie@lockie.ca> wrote:
>
> I have a Gigabyte GeForce 1050 connected by DVI to a monitor (1920x1200
> resolution @ 59.9502 Hz) and a TV via HDMI (3840x2160 @30 Hz).
> The problem is the TV used  to work at 59.9685 Hz but then it started
> showing "No signal" on the TV.
> I was changing settings trying to get it to work again and I happened to
> change it to 30Hz and it worked.
> The specs are here:
> https://www.gigabyte.com/Graphics-Card/GV-N1050OC-2GD/sp#sp
>  >Digital max resolution: 7680x4320
> I should be ok resolution wise.
> Could it be a poor cable?
> kernel: 5.0.0-23-generic
>
> _______________________________________________
> Nouveau mailing list
> Nouveau@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/nouveau
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Re: unstable refresh rate

[James]

On 2019-08-06 12:32 p.m., Ilia Mirkin wrote:
> Hi James,
> 
> I semi-recently added support for HDMI 2.0 (in 4.20+, so you're good),
> which is why you got 60Hz in the first place. In order for the high
> rates to work, something called "scrambling" must be enabled. This is
> done by 2-party agreement between the sink and the source. The sink
> will inform the source that it's about to use scrambling (by writing
> to the SCDC register on the display over i2c).
> 
> In my personal experiments, on a LG C6 series TV, I found that while
> EDID works while the TV is off, the SCDC write does not. So you can
> actually "turn on" the display on the computer while the TV itself is
> off, and the scrambling setting will not have been propagated. Then
> when you turn the TV on, it doesn't work. In order to remedy this, you
> need to disable the display linux-side, and re-enable it.
> 
> The indicator for this sort of issue would be something about SCDC
> reads/writes failing in dmesg -- do you see anything of the sort?
> (Something like "Failure to write SCDC_TMDS_CONFIG")
> 
> If not, it's probably something else. But this seems like a likely candidate.
There is nothing in dmesg.
Maybe nouveau needs a module parameter for debug logging?
I'm going to try a different cable anyways.
Is there something in /proc to check if "scrambling" is on?
I do have a 4k LG tv.
> 
> On Tue, Aug 6, 2019 at 12:14 PM James <bjlockie@lockie.ca> wrote:
>>
>> I have a Gigabyte GeForce 1050 connected by DVI to a monitor (1920x1200
>> resolution @ 59.9502 Hz) and a TV via HDMI (3840x2160 @30 Hz).
>> The problem is the TV used  to work at 59.9685 Hz but then it started
>> showing "No signal" on the TV.
>> I was changing settings trying to get it to work again and I happened to
>> change it to 30Hz and it worked.
>> The specs are here:
>> https://www.gigabyte.com/Graphics-Card/GV-N1050OC-2GD/sp#sp
>>   >Digital max resolution: 7680x4320
>> I should be ok resolution wise.
>> Could it be a poor cable?
>> kernel: 5.0.0-23-generic


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Re: unstable refresh rate

[James]

I was going to buy a new cable and I came across this description:
 >Category 2 Certified HDMI wire supports resolutions up to 4Kx2K (UHD) 
@30 Hz

https://www.cnet.com/how-to/what-is-hdmi-2-0b/
> HDMI versions compared
> HDMI Version 	Max Resolution 	Max 4K Frame rate 	HDCP 2.2 	HDR 	WCG 	Hybrid Log Gamma 	Dynamic Metadata
> 1.4 	4K 	30Hz 	No 	No 	No 	No 	No
> 2.0 	4K 	60Hz 	Yes 	No 	No 	No 	No
> 2.0a 	4K 	60Hz 	Yes 	Yes 	Yes 	No 	No
> 2.0b 	4K 	60Hz 	Yes 	Yes 	Yes 	Yes 	No
> 2.1 	10K 	120Hz 	Yes 	Yes 	Yes 	Yes 	Yes 

"Category 2" implies HDMI 2 but the "Max 4K Frame rate" of 30Hz says it 
is HDMI-1.4.

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Re: unstable refresh rate

[Ilia Mirkin]

Can you try something very simple - unplug the cable, and plug it back
in, while the TV is on, and set to the HDMI input? That should ensure
that the SCDC write can go through at modeset time.

You can also force nouveau to avoid any modes that require scrambling
by booting with nouveau.hdmimhz=340.

Cheers,

  -ilia

On Tue, Aug 6, 2019 at 1:15 PM James <bjlockie@lockie.ca> wrote:
>
> I was going to buy a new cable and I came across this description:
>  >Category 2 Certified HDMI wire supports resolutions up to 4Kx2K (UHD)
> @30 Hz
>
> https://www.cnet.com/how-to/what-is-hdmi-2-0b/
> > HDMI versions compared
> > HDMI Version  Max Resolution  Max 4K Frame rate       HDCP 2.2        HDR     WCG     Hybrid Log Gamma        Dynamic Metadata
> > 1.4   4K      30Hz    No      No      No      No      No
> > 2.0   4K      60Hz    Yes     No      No      No      No
> > 2.0a  4K      60Hz    Yes     Yes     Yes     No      No
> > 2.0b  4K      60Hz    Yes     Yes     Yes     Yes     No
> > 2.1   10K     120Hz   Yes     Yes     Yes     Yes     Yes
>
> "Category 2" implies HDMI 2 but the "Max 4K Frame rate" of 30Hz says it
> is HDMI-1.4.
>
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Re: unstable refresh rate

[James Lockie]

On August 6, 2019 1:36:09 p.m. Ilia Mirkin <imirkin@alum.mit.edu> wrote:

> Can you try something very simple - unplug the cable, and plug it back
> in, while the TV is on, and set to the HDMI input?
I still only get 30Hz.
I did just update the tv firmware s9 maybe that is why I can't get it 60Hz 
anymore.
I wish I kept better track of the timeline.

With the new HDMI 2 cable I get 4096x2160@30Hz (there is no 60Hz option).
3840x2160@59.9685Hz gives me no signal.


> That should ensure
> that the SCDC write can go through at modeset time.
>
> You can also force nouveau to avoid any modes that require scrambling
> by booting with nouveau.hdmimhz=340.
>
> Cheers,
>
>  -ilia
>
> On Tue, Aug 6, 2019 at 1:15 PM James <bjlockie@lockie.ca> wrote:
>>
>> I was going to buy a new cable and I came across this description:
>>> Category 2 Certified HDMI wire supports resolutions up to 4Kx2K (UHD)
>> @30 Hz
>>
>> https://www.cnet.com/how-to/what-is-hdmi-2-0b/
>>> HDMI versions compared
>>> HDMI Version  Max Resolution  Max 4K Frame rate       HDCP 2.2        HDR   
>>>   WCG     Hybrid Log Gamma        Dynamic Metadata
>>> 1.4   4K      30Hz    No      No      No      No      No
>>> 2.0   4K      60Hz    Yes     No      No      No      No
>>> 2.0a  4K      60Hz    Yes     Yes     Yes     No      No
>>> 2.0b  4K      60Hz    Yes     Yes     Yes     Yes     No
>>> 2.1   10K     120Hz   Yes     Yes     Yes     Yes     Yes
>>
>> "Category 2" implies HDMI 2 but the "Max 4K Frame rate" of 30Hz says it
>> is HDMI-1.4.
>>
>> _______________________________________________
>> Nouveau mailing list
>> Nouveau@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/nouveau



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Re: unstable refresh rate

[James]

I think I may have updated the tv firmware between when it worked and 
when it didn't.
I wonder it it has to do with bit depth.
I use lubuntu and it doesn't let me pick the bit depth so I don't know 
what it using.

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Re: unstable refresh rate

[Ilia Mirkin]

That's OK - nouveau doesn't let you pick bit depth either (yet). It's
all 8bpc - higher bpc mode support will come ... eventually.

On Tue, Aug 6, 2019 at 5:25 PM James <bjlockie@lockie.ca> wrote:
>
> I think I may have updated the tv firmware between when it worked and
> when it didn't.
> I wonder it it has to do with bit depth.
> I use lubuntu and it doesn't let me pick the bit depth so I don't know
> what it using.
>
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> Nouveau@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/nouveau
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Re: unstable refresh rate

[James]

Do you know why xrandr rounds up to "3840x2160     59.97" but the 
lubuntu GUI says "3840x2160     59.9685"?

I thought it might be the TV only does 30Hz or 60Hz but it does 
fractional rates at lower resolutions.
I don't know.
Maybe it is the colour depth.
Why is my first monitor 1920x1200 for :Width" and "Height"?

$ xwininfo
   Absolute upper-left X:  2
   Absolute upper-left Y:  62
   Relative upper-left X:  2
   Relative upper-left Y:  30
   Width: 1912
   Height: 1136
   Depth: 24
   Visual: 0x3e9
   Visual Class: TrueColor
   Border width: 0
   Class: InputOutput
   Colormap: 0x2c00002 (not installed)
   Bit Gravity State: NorthWestGravity
   Window Gravity State: NorthWestGravity
   Backing Store State: NotUseful
   Save Under State: no
   Map State: IsViewable
   Override Redirect State: no
   Corners:  +2+62  -3846+62  -3846-962  +2-962
   -geometry 1912x1136+0+32


$ xwininfo
   Absolute upper-left X:  0
   Absolute upper-left Y:  0
   Relative upper-left X:  0
   Relative upper-left Y:  0
   Width: 5760
   Height: 2160
   Depth: 24
   Visual: 0x3e9
   Visual Class: TrueColor
   Border width: 0
   Class: InputOutput
   Colormap: 0xa00005 (not installed)
   Bit Gravity State: NorthWestGravity
   Window Gravity State: NorthWestGravity
   Backing Store State: NotUseful
   Save Under State: no
   Map State: IsViewable
   Override Redirect State: no
   Corners:  +0+0  -0+0  -0-0  +0-0
   -geometry 5760x2160+0+0


$ xrandr
Screen 0: minimum 320 x 200, current 5760 x 2160, maximum 16384 x 16384
DVI-D-1 connected primary 1920x1200+0+0 (normal left inverted right x 
axis y axis) 518mm x 324mm
    1920x1200     59.95*+
    1920x1080     59.96    60.00    50.00    59.94    59.93
    1920x1080i    60.00    50.00    59.94
    1600x1200     65.00    60.00
    1680x1050     69.88    59.95    59.88
    1600x1024     60.17
    1400x1050     74.76    70.00    59.98
    1600x900      59.95    59.82
    1280x1024     75.02    60.02
    1440x900      59.89
    1400x900      59.96    59.88
    1280x960      60.00
    1440x810      59.97
    1368x768      59.88    59.85
    1360x768      59.80    59.96
    1280x800      59.99    59.97    59.81    59.91
    1152x864      75.00    75.00    70.00    60.00
    1280x720      60.00    59.99    59.86    60.00    50.00    59.94 59.74
    1024x768      75.05    60.04    75.03    70.07    60.00
    960x720       75.00    60.00
    928x696       75.00    60.05
    896x672       75.05    60.01
    1024x576      59.95    59.96    59.90    59.82
    960x600       59.93    60.00
    832x624       74.55
    960x540       59.96    59.99    59.63    59.82
    800x600       75.00    70.00    65.00    60.00    72.19    75.00 
60.32    56.25
    840x525       74.96    69.88    60.01    59.88
    864x486       59.92    59.57
    800x512       60.17
    700x525       74.76    70.06    59.98
    800x450       59.95    59.82
    640x512       75.02    60.02
    720x450       59.89
    700x450       59.96    59.88
    640x480       60.00    75.00    72.81    75.00    66.67    60.00 59.94
    720x405       59.51    58.99
    720x400       70.08
    684x384       59.88    59.85
    680x384       59.80    59.96
    640x400       59.88    59.98
    576x432       75.00    75.00    70.00    60.06
    640x360       59.86    59.83    59.84    59.32
    512x384       75.03    70.07    60.00
    512x288       60.00    59.92
    416x312       74.66
    480x270       59.63    59.82
    400x300       72.19    75.12    60.32    56.34
    432x243       59.92    59.57
    320x240       72.81    75.00    60.05
    360x202       59.51    59.13
    320x180       59.84    59.32
HDMI-1 connected 3840x2160+1920+0 (normal left inverted right x axis y 
axis) 1600mm x 900mm
    4096x2160     30.00    25.00    24.00    29.97    23.98
    3840x2160     59.97    30.00*   25.00    24.00    29.97    23.98
    3200x1800     59.96    59.94
    2880x1620     59.96    59.97
    2560x1600     59.99    59.97
    2560x1440     59.99    59.96    59.95
    2048x1536     85.00    75.00    60.00
    1920x1440     85.00    75.00    60.00
    1856x1392     75.00    60.01
    1792x1344     75.00    60.01
    2048x1152     59.99    59.98    59.90    59.91
    1920x1200     59.88    59.95
    1920x1080     60.01   120.00   100.00   119.88    59.97    59.96 
60.00    50.00    59.94    59.93    30.00    25.00    24.00    29.97 23.98
    1920x1080i    60.00    50.00    59.94
    1600x1200     85.00    75.00    70.00    65.00    60.00
    1680x1050     84.94    74.89    69.88    59.95    59.88
    1600x1024     60.17
    1400x1050     85.00    74.76    70.00    59.98
    1600x900      59.99    59.94    59.95    59.82
    1280x1024     85.02    75.02    60.02
    1440x900      59.89
    1400x900      59.96    59.88
    1280x960      85.00    60.00
    1440x810      60.00    59.97
    1368x768      59.88    59.85
    1360x768      60.02    59.80    59.96
    1280x800      59.99    59.97    59.81    59.91
    1152x864     100.00    85.06    85.00    75.00    75.00    70.00 
60.00    59.97
    1280x720      60.00    59.99    59.86    60.00    50.00    59.94 59.74
    1024x768      85.00    75.05    60.04    85.00    75.03    70.07 60.00
    1024x768i     86.96
    960x720       85.00    75.00    60.00
    928x696       75.00    60.05
    896x672       75.05    60.01
    1024x576      59.95    59.96    59.90    59.82
    960x600       59.93    60.00
    832x624       74.55
    960x540       59.96    59.99    59.63    59.82
    800x600       85.00    75.00    70.00    65.00    60.00    85.14 
72.19    75.00    60.32    56.25
    840x525       85.02    74.96    69.88    60.01    59.88
    864x486       59.92    59.57
    720x576       50.00
    800x512       60.17
    700x525       85.08    74.76    70.06    59.98
    800x450       59.95    59.82
    720x480       60.00    59.94
    640x512       85.02    75.02    60.02
    720x450       59.89
    700x450       59.96    59.88
    640x480       85.09    60.00    85.01    72.81    75.00    60.00 59.94
    720x405       59.51    58.99
    720x400       85.04    70.08
    684x384       59.88    59.85
    680x384       59.80    59.96
    640x400       59.88    59.98    85.08
    576x432      100.11    85.15    85.09    75.00    75.00    70.00 60.06
    640x360       59.86    59.83    59.84    59.32
    640x350       85.08
    512x384       85.00    75.03    70.07    60.00
    512x384i      87.06
    512x288       60.00    59.92
    416x312       74.66
    480x270       59.63    59.82
    400x300       85.27    72.19    75.12    60.32    56.34
    432x243       59.92    59.57
    320x240       85.18    72.81    75.00    60.05
    360x202       59.51    59.13
    360x200       85.04
    320x200       85.27
    320x180       59.84    59.32
    320x175       85.27
DP-1 disconnected (normal left inverted right x axis y axis)


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