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

[Martin Peres]

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

Because of this, I am a little uneasy and cannot say for sure that my 
patch for -modesetting is correct. I am hoping that Manasi will get a 
good testing rig to validate everything from end-to-end. At the very 
least, -modesetting seems to do a reasonable job.

Sorry for keeping you out of the loop, but I was hoping to have a more 
clear-cut GOOD/BAD, but I seem to be mostly at a road block. Manasi told 
me it would help if I described it here, so here I am. I will continue 
assisting Manasi in her validation work!

Martin

PS: My kernel tree is here: https://cgit.freedesktop.org/~mperes/linux