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

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

[Daniel Vetter]

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. */
+	if (!intel_dp->lane_count)
 		return;
 
 	/* if link training is requested we should perform it always */
-- 
2.11.0

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

[Linus Torvalds]

On Tue, Dec 13, 2016 at 11:54 AM, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>
> Feel free to apply directly in case it annoys too much and you don't
> want to wait for your presents ;-)

I'll wait for the proper unboxing of presents. Once I've rattled them
and know what to expect, I can be very patient.

             Linus

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

[Ville Syrjälä]

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 Syrj�l� <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.

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 Syrj�l� <ville.syrjala@linux.intel.com>

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

-- 
Ville Syrj�l�
Intel OTC

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

[Daniel Vetter]

On Tue, Dec 13, 2016 at 10:23:05PM +0200, Ville Syrj�l� 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 Syrj�l� <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 Syrj�l� <ville.syrjala@linux.intel.com>

... and merged since CI seems to approve too ;-)
-Daniel

> 

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

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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

[Jani Nikula]

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

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

[Daniel Vetter]

On Wed, Dec 14, 2016 at 04:56:33PM +0200, Jani Nikula wrote:
> On Wed, 14 Dec 2016, Daniel Vetter <daniel@ffwll.ch> wrote:
> > On Tue, Dec 13, 2016 at 10:23:05PM +0200, Ville Syrj�l� 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 Syrj�l� <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 Syrj�l� <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. :(

I've made a JIRA internally to fix this and assigned it to Paul Parenteau
for handling with his DP folks. But I'm happy to also r-b stamp a patch
that adds some debug output here if you want that too. At least I thought
the problem is fairly well-understood, so didn't think this was needed.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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

[Jani Nikula]

On Thu, 15 Dec 2016, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Wed, Dec 14, 2016 at 04:56:33PM +0200, Jani Nikula wrote:
>> 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. :(
>
> I've made a JIRA internally to fix this and assigned it to Paul Parenteau
> for handling with his DP folks. But I'm happy to also r-b stamp a patch
> that adds some debug output here if you want that too. At least I thought
> the problem is fairly well-understood, so didn't think this was needed.

Oh, okay. Then it's just that *I* didn't understand the problem well. :(

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Technology Center