[Intel-gfx] [PATCH v2] drm/i915/display: Increase AUX timeout for Type-C

[Kandpal, Suraj]

> -----Original Message-----
> From: Jani Nikula <jani.nikula at linux.intel.com>
> Sent: Monday, April 17, 2023 4:04 PM
> To: Kandpal, Suraj <suraj.kandpal at intel.com>; intel-
> gfx at lists.freedesktop.org
> Subject: RE: [Intel-gfx] [PATCH v2] drm/i915/display: Increase AUX timeout
> for Type-C
> 
> On Mon, 17 Apr 2023, "Kandpal, Suraj" <suraj.kandpal at intel.com> wrote:
> >> On Wed, 05 Apr 2023, Suraj Kandpal <suraj.kandpal at intel.com> wrote:
> >> > Type-C PHYs are taking longer than expected for Aux IO Power Enabling.
> >> > Workaround: Increase the timeout.
> >> >
> >> > WA_14017248603: adlp
> >> > Bspec: 55480
> >> >
> >> > ---v2
> >> > -change style on how we mention WA [Ankit] -fix bat error
> >> >
> >> > Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> >> > ---
> >> >  .../i915/display/intel_display_power_well.c   | 30 ++++++++++++++++++-
> >> >  1 file changed, 29 insertions(+), 1 deletion(-)
> >> >
> >> > diff --git
> >> > a/drivers/gpu/drm/i915/display/intel_display_power_well.c
> >> > b/drivers/gpu/drm/i915/display/intel_display_power_well.c
> >> > index 62bafcbc7937..52f595929a18 100644
> >> > --- a/drivers/gpu/drm/i915/display/intel_display_power_well.c
> >> > +++ b/drivers/gpu/drm/i915/display/intel_display_power_well.c
> >> > @@ -489,6 +489,34 @@ static void icl_tc_cold_exit(struct
> >> drm_i915_private *i915)
> >> >  		    "succeeded");
> >> >  }
> >> >
> >> > +static void
> >> > +adl_aux_wait_for_power_well_enable(struct drm_i915_private *i915,
> >> > +				   struct i915_power_well *power_well,
> >> > +				   bool timeout_expected)
> >> > +{
> >> > +	const struct i915_power_well_regs *regs = power_well->desc->ops-
> >> >regs;
> >> > +	enum phy phy = icl_aux_pw_to_phy(i915, power_well);
> >> > +	int pw_idx = i915_power_well_instance(power_well)->hsw.idx;
> >> > +
> >> > +	/*
> >> > +	 * WA_14017248603: adlp
> >> > +	 * Type-C Phy are taking longer than expected for AUX IO Power
> >> Enabling.
> >> > +	 * Increase timeout to 500ms.
> >> > +	 */
> >> > +	if (IS_ALDERLAKE_P(i915) && intel_phy_is_tc(i915, phy)) {
> >> > +		if (intel_de_wait_for_set(i915, regs->driver,
> >> > +
> >> HSW_PWR_WELL_CTL_STATE(pw_idx), 500)) {
> >> > +			drm_dbg_kms(&i915->drm, "%s power well enable
> >> timeout\n",
> >> > +				    intel_power_well_name(power_well));
> >> > +
> >> > +			drm_WARN_ON(&i915->drm, !timeout_expected);
> >> > +		}
> >> > +		return;
> >> > +	}
> >> > +
> >> > +	hsw_wait_for_power_well_enable(i915, power_well,
> >> timeout_expected);
> >> > +}
> >>
> >> Please don't duplicate the function and the wait like this.
> >>
> >> Something like this is sufficient:
> >>
> >>
> >> @@ -252,7 +252,9 @@ static void
> hsw_wait_for_power_well_enable(struct
> >> drm_i915_private *dev_priv,
> >>  					   bool timeout_expected)
> >>  {
> >>  	const struct i915_power_well_regs *regs = power_well->desc->ops-
> >> >regs;
> >> +	enum phy phy = icl_aux_pw_to_phy(i915, power_well);
> >>  	int pw_idx = i915_power_well_instance(power_well)->hsw.idx;
> >> +	int timeout = 1;
> >>
> >>  	/*
> >>  	 * For some power wells we're not supposed to watch the status bit
> >> for @@ -264,9 +266,13 @@ static void
> >> hsw_wait_for_power_well_enable(struct drm_i915_private *dev_priv,
> >>  		return;
> >>  	}
> >>
> >> +	/* WA_14017248603: adlp */
> >> +	if (IS_ALDERLAKE_P(i915) && intel_phy_is_tc(i915, phy))
> >
> > I did try this but it ends up throwing a kernel null pointer error at
> > intel_phy_is_tc which made me float the version of code I did.
> 
> Please explain what causes it, and how your version avoids it.
> 

icl_aux_pw_to_phy is called is hsw_wait_for_power_well is called everywhere where its not possible for aux_pw to phy
conversion is not possible with this change we only get the phy for adls version.
Will address this is next version.

Regards,
Suraj Kandpal
> BR,
> Jani.
> 
> 
> >
> > Regards,
> > Suraj Kandpal
> >> +		timeout = 500;
> >> +
> >>  	/* Timeout for PW1:10 us, AUX:not specified, other PWs:20 us. */
> >>  	if (intel_de_wait_for_set(dev_priv, regs->driver,
> >> -				  HSW_PWR_WELL_CTL_STATE(pw_idx), 1)) {
> >> +				  HSW_PWR_WELL_CTL_STATE(pw_idx),
> >> timeout)) {
> >>  		drm_dbg_kms(&dev_priv->drm, "%s power well enable
> timeout\n",
> >>  			    intel_power_well_name(power_well));
> >>
> >>
> >> > +
> >
> >> >  static void
> >> >  icl_tc_phy_aux_power_well_enable(struct drm_i915_private *dev_priv,
> >> >  				 struct i915_power_well *power_well) @@ -
> >> 517,7 +545,7 @@
> >> > icl_tc_phy_aux_power_well_enable(struct drm_i915_private *dev_priv,
> >> >  	if (DISPLAY_VER(dev_priv) == 11 &&
> >> intel_tc_cold_requires_aux_pw(dig_port))
> >> >  		icl_tc_cold_exit(dev_priv);
> >> >
> >> > -	hsw_wait_for_power_well_enable(dev_priv, power_well,
> >> timeout_expected);
> >> > +	adl_aux_wait_for_power_well_enable(dev_priv, power_well,
> >> > +timeout_expected);
> >>
> >> A function prefixed adl_ should indicate it's only needed for adl+.
> >> This change is misleading.
> >>
> >> BR,
> >> Jani.
> >>
> >>
> >> >
> >> >  	if (DISPLAY_VER(dev_priv) >= 12 && !is_tbt) {
> >> >  		enum tc_port tc_port;
> >>
> >> --
> >> Jani Nikula, Intel Open Source Graphics Center
> 
> --
> Jani Nikula, Intel Open Source Graphics Center