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From: Daniel Vetter <daniel@ffwll.ch>
To: Dave Airlie <airlied@gmail.com>
Cc: "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>
Subject: Re: limiting modes on 4k monitors on Haswell ULT
Date: Thu, 2 Oct 2014 10:00:50 +0200	[thread overview]
Message-ID: <20141002080050.GU12343@phenom.ffwll.local> (raw)
In-Reply-To: <CAPM=9tye0vGi1999_XXh1u6P49uqvMr=-qVQENJXk4Y0U49Q-A@mail.gmail.com>

On Thu, Oct 02, 2014 at 01:30:48PM +1000, Dave Airlie wrote:
> Hey guys,
> 
> so I have a haswell ULT laptop (lenovo t440s), and got access to a
> Samsung single panel 4k monitor (no MST).
> 
> Now we detect the monitor fine, but unfortunately the ULT hsw can't
> run it over DP, as it has clock limits in place. However we still
> offer the 60hz mode and we pick it by default, ensuing black screens.
> 
> I've tested the same monitor with a haswell in a t540p and it works
> fine due to having the higher limits in place.

We have the IS_HSW_ULX check in intel_dp_max_link_bw, and that's used by
both compute_config and mode_valid. So it should work, and from a quick
look I don't see any bugs. But obviously something is busted.

Can you please printk-augment intel_dp_mode_valid and check what's going
wrong there?

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

  reply	other threads:[~2014-10-02  8:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-02  3:30 limiting modes on 4k monitors on Haswell ULT Dave Airlie
2014-10-02  8:00 ` Daniel Vetter [this message]
2014-10-02  8:40   ` Ville Syrjälä
2014-10-02 10:56     ` Dave Airlie
2014-10-07 13:07       ` Ville Syrjälä
2014-10-02 11:15   ` Damien Lespiau

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