[Bug 70331] Incorrect resolution reported for monitor

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=70331

--- Comment #8 from Jani Nikula <jani.nikula at intel.com> ---
On a hunch I'd say this is caused by

commit 7d148ef51a657fd04036c3ed7803da600dd0d451
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Mon Jul 22 18:02:39 2013 +0200

    drm/i915: fix hdmi portclock limits

Before the change, the 172.7 MHz clock reported in edid for the 1920x1080 mode
was pruned with MODE_CLOCK_HIGH, but not afterwards.

The problem is, the change is valid for HDMI. You experience the issue because
you're using an HDMI->DVI adapter, and the 172.7 MHz clock exceeds the
single-link DVI maximum of 165 MHz.

Since the monitor reports the mode on DVI, I presume the monitor would support
the mode with dual-link DVI. But it's also possible the monitor reports a bogus
mode... Anyway, simple passive adapters won't work for HDMI->dual-link-DVI.
Active adapters for this are likely hard to come by, and may be problematic.

Ville, I'm wondering if we should check for intel_hdmi->has_hdmi_sink in
hdmi_portclock_limit() and limit to 165 MHz for non-hdmi. Does that sounds sane
to you?

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