[Intel-gfx] [PATCH 3/3] drm/i915/edp: Fix warning as vdd went down without driver knowledge

[Manna, Animesh]

> -----Original Message-----
> From: Nikula, Jani <jani.nikula at intel.com>
> Sent: Wednesday, November 9, 2022 3:26 PM
> To: Manna, Animesh <animesh.manna at intel.com>; intel-
> gfx at lists.freedesktop.org
> Cc: Manna, Animesh <animesh.manna at intel.com>; Ville Syrjälä
> <ville.syrjala at linux.intel.com>; Shankar, Uma <uma.shankar at intel.com>
> Subject: Re: [PATCH 3/3] drm/i915/edp: Fix warning as vdd went down without
> driver knowledge
> 
> On Wed, 09 Nov 2022, Animesh Manna <animesh.manna at intel.com> wrote:
> > Kernel warning triggered as vdd went down after certain time during
> > aux transfer in connector init sequence. To solve the kernel warning
> > adjust power domain and vdd wakeref count.
> > Currently issue seen on ADL so add the above adjustment part of ADL
> > platform check, if needed will extend for future platform.
> 
> Do you understand where the original
> drm_WARN_ON(intel_dp->pps.vdd_wakeref) warning comes from and why?
> 
> What is this one? What are you doing here? Do you have a backtrace of this
> when running patches 1&2?

With the patch series - https://patchwork.freedesktop.org/series/109820/
&
The following log - https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_109820v2/bat-adlp-4/igt@i915_module_load@load.html

We can see the WARN_ON() called after 

<7> [114.864669] i915 0000:00:02.0: [drm:intel_panel_add_edid_fixed_modes [i915]] [CONNECTOR:236:eDP-1] using preferred EDID fixed mode: "1920x1080": 60 138500 1920 1968 2000 2080 1080 1083 1088 1111 0x48 0xa
<7> [114.864784] i915 0000:00:02.0: [drm:intel_panel_add_edid_fixed_modes [i915]] [CONNECTOR:236:eDP-1] using alternate EDID fixed mode: "1920x1080": 30 69320 1920 1968 2000 2080 1080 1083 1088 1111 0x40 0xa
<4> [114.864923] ------------[ cut here ]------------
<4> [114.864927] i915 0000:00:02.0: drm_WARN_ON(intel_dp->pps.vdd_wakeref)
<4> [114.864951] WARNING: CPU: 4 PID: 1281 at drivers/gpu/drm/i915/display/intel_pps.c:603 intel_pps_vdd_on_unlocked+0x2b8/0x2d0 [i915]

My fix also added in intel_pps_vdd_on_unlocked() only.

I have run with the fix and warning is not seen. 
Can you please let me know if this changes looks ok.
Please me know for any additional info.

Regards,
Animesh

> 
> BR,
> Jani.
> 
> >
> > Cc: Jani Nikula <jani.nikula at intel.com>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Cc: Uma Shankar <uma.shankar at intel.com>
> > Signed-off-by: Animesh Manna <animesh.manna at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_pps.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_pps.c
> > b/drivers/gpu/drm/i915/display/intel_pps.c
> > index 0975e49f8d03..1857bbcc6fd4 100644
> > --- a/drivers/gpu/drm/i915/display/intel_pps.c
> > +++ b/drivers/gpu/drm/i915/display/intel_pps.c
> > @@ -587,8 +587,15 @@ bool intel_pps_vdd_on_unlocked(struct intel_dp
> *intel_dp)
> >  	cancel_delayed_work(&intel_dp->pps.panel_vdd_work);
> >  	intel_dp->pps.want_panel_vdd = true;
> >
> > -	if (edp_have_panel_vdd(intel_dp))
> > +	if (edp_have_panel_vdd(intel_dp)) {
> >  		return need_to_disable;
> > +	} else {
> > +		if ((IS_ALDERLAKE_S(dev_priv) || IS_ALDERLAKE_P(dev_priv))
> &&
> > +		    intel_dp->pps.vdd_wakeref)
> > +			intel_display_power_put(dev_priv,
> > +
> 	intel_aux_power_domain(dig_port),
> > +						fetch_and_zero(&intel_dp-
> >pps.vdd_wakeref));
> > +	}
> >
> >  	drm_WARN_ON(&dev_priv->drm, intel_dp->pps.vdd_wakeref);
> >  	intel_dp->pps.vdd_wakeref = intel_display_power_get(dev_priv,
> 
> --
> Jani Nikula, Intel Open Source Graphics Center