[Intel-gfx] [PATCH 0/2] drm: link status property and DP link training failure handling

[Ville Syrjälä]

On Wed, Jan 18, 2017 at 11:05:18PM +0200, Martin Peres wrote:
> On 16/12/16 15:48, Daniel Vetter wrote:
> > On Fri, Dec 16, 2016 at 12:29:05PM +0200, Jani Nikula wrote:
> >> The two remaining patches from [1], rebased.
> >>
> >> BR,
> >> Jani.
> >>
> >>
> >> [1] http://mid.mail-archive.com/1480984058-552-1-git-send-email-manasi.d.navare@intel.com
> >
> > Just for the record, I think the only thing missing here is the Xorg
> > review on the -modesetting patch. As soon as we have that I can vacuum
> > this up (probably best through drm-misc, but not sure).
> 
> Hey Daniel,
> 
> I tested again on Monday -modesetting with the patch from Jani to inject 
> faults and did manage to get both the link-status BAD and a lower 
> resolution got select dynamically when running KDE. For the latter, I 
> however needed the following patch: 
> https://patchwork.kernel.org/patch/9491869/
> 
> Now, that being said, Jani's patch just prevents a new modeset to work, 
> it does not tear down the current mode. This may be the reason why I do 
> not manage to get a black screen after > 3 failures (and already a 
> 1024x768 resolution).
> 
> I however need to do more testing when running without a DE (straight X 
> + twm and xterm). Indeed, when I hotplug my DP screen, it gets to the 
> native resolution automatically without me asking for it using xrandr. 
> Also, the mode that is set does not seem to go through 
> intel_dp_start_link_train (what the heck?), so I do not get any failure 
> and I cannot induce one :s

Presumably you're already pushing pixels out at the same resolution and
the monitor just syncs up to it. I think depending on the monitor that
might happen w/ or w/o link retraining.

-- 
Ville Syrjälä
Intel OTC