[Intel-gfx] PROBLEM: i915 Haswell KMS wrong maximum resolution

[Kenneth de Mello]

Jani,

Thank you for explaining further.   After checking the manual for my
motherboard, I am mistaken.   It specifies DVI-I and states the maximum
resolution over DVI is 1920x1200 at 60Hz, so it appears all is well.   The
fact it worked before is a happy accident.

I have since switched to use displayport, and it is detecting the native
resolution as expected.


Thank you for your time,

BR,
Kenneth

On Mon, Mar 31, 2014 at 3:43 AM, Jani Nikula <jani.nikula at linux.intel.com>wrote:

> On Sun, 30 Mar 2014, Kenneth de Mello <kdemello1980 at gmail.com> wrote:
> > What about dual-link DVI?   I though the additional link addressed the
> > pixel clock limitation.   Has it only been using a single link this
> entire
> > time, and it's only worked by ignoring the maximum dotclock, so in other
> > words, the fact it works at all is the bug?
> >
> > Also, the commit that rejects mode exceeding 165MHz states:
> >
> >     "Single-link DVI max dotclock is 165MHz. Filter out modes with higher
> >      dotclock when the monitor doesn't support HDMI."
> >
> > Does this mean HDMI in general?   This monitor does support HDMI, but the
> > maximum resolution when using the physical HDMI ports is 1920x1080.
> >
> > What is the solution here, to switch to displayport if I want to use
> kernel
> > 3.13.7 and beyond?   (This is fine, I just need to know so I can buy the
> > cable).
>
> For further details please see the bug report [1].
>
> The reason for the change was that modes with higher than 165 MHz
> dotclock are invalid for single-link DVI. We don't support dual-link DVI
> natively. Thus this is about HDMI->DVI adapters which are either
> dual-link DVI (Ville says highly unlikely) or single-link DVI that allow
> higher than 165 MHz dotclock in the monitor end. I'm not sure how we
> could distinguish that from a regular single-link DVI that *is* bound by
> the maximum dotclock.
>
> Product details for the adapter you're using might be interesting.
>
> BR,
> Jani.
>
>
>
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=72961
>
>
> --
> Jani Nikula, Intel Open Source Technology Center
>
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