Re: [PATCH] drm/i915: tune down the fast link training vs boot fail

From: Jani Nikula <jani.nikula@linux.intel.com>
To: "Daniel Vetter" <daniel@ffwll.ch>,
	"Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	stable@vger.kernel.org, Daniel Vetter <daniel.vetter@intel.com>
Subject: Re: [PATCH] drm/i915: tune down the fast link training	vs boot fail
Date: Wed, 14 Dec 2016 16:56:33 +0200	[thread overview]
Message-ID: <87bmwer23i.fsf@intel.com> (raw)
In-Reply-To: <20161213223722.xxgheqytlrvsi36d@phenom.ffwll.local>

On Wed, 14 Dec 2016, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Tue, Dec 13, 2016 at 10:23:05PM +0200, Ville Syrjälä wrote:
>> On Tue, Dec 13, 2016 at 08:54:14PM +0100, Daniel Vetter wrote:
>> > It's been unfixed since a while and no one is immediately working on
>> > this. And we have the FIXME already. And now also a task in the DP
>> > team's backlog.
>> > 
>> > Cc: Linus Torvalds <torvalds@linux-foundation.org>
>> > Cc: stable@vger.kernel.org
>> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> > References: https://lists.freedesktop.org/archives/intel-gfx/2016-July/101951.html
>> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
>> > ---
>> > Hi Linus,
>> > 
>> > Feel free to apply directly in case it annoys too much and you don't
>> > want to wait for your presents ;-)
>> > 
>> > Cheers, Daniel
>> > ---
>> >  drivers/gpu/drm/i915/intel_dp.c | 4 ++--
>> >  1 file changed, 2 insertions(+), 2 deletions(-)
>> > 
>> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> > index db75bb924e48..6e875d42642a 100644
>> > --- a/drivers/gpu/drm/i915/intel_dp.c
>> > +++ b/drivers/gpu/drm/i915/intel_dp.c
>> > @@ -4014,8 +4014,8 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
>> >  		return;
>> >  
>> >  	/* FIXME: we need to synchronize this sort of stuff with hardware
>> > -	 * readout */
>> > -	if (WARN_ON_ONCE(!intel_dp->lane_count))
>> > +	 * readout. Currently fast link training doesn't work on boot-up. */
>> 
>> s/fast link training/link retraining/ is what I'd put there.
>
> Adjusted ...
>> 
>> I'm a bit sad to hide it but doesn't look like the proper solution is
>> going to happen any time soon.
>> 
>> Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> ... and merged since CI seems to approve too ;-)

*sigh* you could've added debug logging at least. Now it's pretty much
guaranteed nobody will look at this. It's not right to end up here
without link params. :(

BR,
Jani.

> -Daniel
>
>> 
>
>> > +	if (!intel_dp->lane_count)
>> >  		return;
>> >  
>> >  	/* if link training is requested we should perform it always */
>> > -- 
>> > 2.11.0
>> 
>> -- 
>> Ville Syrjälä
>> Intel OTC

-- 
Jani Nikula, Intel Open Source Technology Center
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