[Bug 102820] [bisected][DC] commit ebbf7337e2daacacef3e01114e6be68a2a4f11b4 prevents X11 from starting

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=102820

--- Comment #9 from Alex Deucher <alexdeucher at gmail.com> ---
(In reply to dwagner from comment #8)
> (In reply to Alex Deucher from comment #7)
> > I think it blocks modes that require 6Ghz timings if the platform isn't
> > validated for them.
> What does "platform isn't validated for 6Ghz timings" mean?
> 
> Both the RX 460 and the 4k TV I use are officially advertised as supporting
> 4k @ 60Hz, and indeed they work just fine in that mode if commit
> ebbf7337e2daacacef3e01114e6be68a2a4f11b4 is not part of the kernel.
> 

Harry or Jordan can verify, but I think it means the board maker did not
validate the HDMI connector for 6Ghz timings.  The asic may support it, but the
board has to be validated to make sure the physical connector supports it and
the traces are not too long, etc.  Some boards only support 4k at 60 over DP.

> > Does everything work correctly if you remove the modes
> > from your monitor section?
> Removing the (not really used) ModeLine statements from the X11 config does
> in fact change the symptoms when commit
> ebbf7337e2daacacef3e01114e6be68a2a4f11b4 is present: X11 will start then,
> but only to use what xrandr says to be a "3840x2160 @ 30Hz" mode, but which
> the display picks up as some not-really-filling-the-whole-screen signal,
> with black borders on both sides (so an image is shown but compressed
> horizontally - in the usually active "just scan" mode and also even if the
> display is manually forced to a 16:9 aspect ratio).

The driver drops the higher bandwidth modes for HDMI connectors if the board
does not support them.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/dri-devel/attachments/20171016/c60178ce/attachment.html>