[Bug 93361] 12bpc hdmi causes wrong real refresh rate (swapbuffers return time)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=93361

--- Comment #14 from Tomeu Vizoso <tomeu at tomeuvizoso.net> ---
(In reply to Kevin Mitchell from comment #0)
> Created attachment 120472 [details]
> Samsung un40eh5000 edid reported by xrandr --prop
> 
> I have a Samsung un40eh5000 tv that I connect to my Ivy Bridge Lenovo T530
> laptop via mini display-port to hdmi. I have attached the raw and decoded
> EDID. 
> 
> As of 7a0baa6234468aa387f9b8a1a79dc2a4b4821f67, it seems 12bpc gets enabled
> on this setup (though I can't imagine that my machine or my TV actually
> support that in real life).

Why do you think that? The EDID says that DC_36bit is supported, and from sandy
bridge up, 12bpc is supported by the graphics hw.

> Unfortunately, this seems to change the
> effective refresh rate as measured between returns from opengl swapbuffers
> calls for example in glxgears.
> 
>        | glxgears fps   |
>        +----------------+
> xrandr | before | after |
> -------+--------+-------+
> 23.98  | 24.00  | 23.85 |
> 24.00  | 24.00  | 24.13 |
> 29.97  | 30.00  | 29.81 |
> 30.00  | 30.00  | 30.17 |
> 59.94  | 60.00  | 60.12 |
> 60.00  | 60.00  | 60.12 |
> 
> This is problematic for displaying video at native frame rates. For example
> when the actual refresh rate of 24.00 hz could be achieved, 23.98fps video
> would only have to repeat a frame every 50 seconds. Now it must either drop
> or repeat one every 7 seconds which is much more noticeable.

So you want a mechanism for disabling deep color even if it could be used?

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20170217/85c97a34/attachment.html>