[Intel-gfx] [PATCH] drm/i915: resume MST after reading back hw state

[Jani Nikula]

On Mon, 08 Dec 2014, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Mon, Dec 08, 2014 at 01:23:37PM +1000, Dave Airlie wrote:
>> From: Dave Airlie <airlied at redhat.com>
>> 
>> Otherwise the MST resume paths can hit DPMS paths
>> which hit state checker paths, which hit WARN_ON,
>> because the state checker is inconsistent with the
>> hw.
>> 
>> This fixes a bunch of WARN_ON's on resume after
>> undocking.
>> 
>> Signed-off-by: Dave Airlie <airlied at redhat.com>
>
> Makes sense, so Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Pushed to drm-intel-next-fixes, thanks for the patch and review.

BR,
Jani.

>
> And Cc: stable at vger.kernel.org when Jani picks it up.
>
> While reading around I've noticed though that we might miss dp mst changes
> after resume:
> - intel_dp_mst_resume checks for can_mst, so will skip if we didn't plug
>   in an mst thing before suspend.
> - drm_helper_hpd_irq_event only does the locked detect dance and doesn't
>   do the unlocked mst dance we do before calling down into ->detect
>   callbacks.
>
> So I think if we plug in an mst dock while suspended and then resume
> we'll miss the hotplug in the kernel. Or do I miss something?
> -Daniel
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch

-- 
Jani Nikula, Intel Open Source Technology Center