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

[Jani Nikula]

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?

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