From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: limiting modes on 4k monitors on Haswell ULT Date: Thu, 2 Oct 2014 10:00:50 +0200 Message-ID: <20141002080050.GU12343@phenom.ffwll.local> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com [209.85.212.182]) by gabe.freedesktop.org (Postfix) with ESMTP id EA25B6E49C for ; Thu, 2 Oct 2014 01:00:54 -0700 (PDT) Received: by mail-wi0-f182.google.com with SMTP id n3so3096484wiv.15 for ; Thu, 02 Oct 2014 01:00:53 -0700 (PDT) Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Dave Airlie Cc: "intel-gfx@lists.freedesktop.org" List-Id: intel-gfx@lists.freedesktop.org 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