[Bug 111553] Linux 4.10 and newer limit pixel clock to 165 MHz on Haswell-ULT laptop

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=111553

--- Comment #7 from Michael Hanselmann (hansmi) <public at hansmi.ch> ---
(In reply to Ville Syrjala from comment #6)
> Nope. Looks like the cmdline mode is treated the same as mode coming from
> the EDID, ie. is subject to getting filtered out from the connector's mode
> list.

That filtering is indeed the case. None of my other attempts like writing to
the adapter and EDID via I²C worked (either the transactions were NACKed or
outright ignored). As I'd rather not maintain my own kernel build I ended up
writing a custom kernel module using Kernel probes to override the return value
from "drm_dp_dual_mode_detect":

https://github.com/hansmi/fake-dp-dual-mode

Now, this is obviously a hack, but it's fine for myself. I'd be able to submit
a kernel patch to add a parameter overriding the automatic detection. Do you
think that'd be worth it?

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