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

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 17 Apr 2023, "Kandpal, Suraj" <suraj.kandpal@intel.com> wrote:
>> -----Original Message-----
>> From: Jani Nikula <jani.nikula@linux.intel.com>
>> Sent: Monday, April 17, 2023 4:04 PM
>> To: Kandpal, Suraj <suraj.kandpal@intel.com>; intel-
>> gfx@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@intel.com> wrote:
>> >> On Wed, 05 Apr 2023, Suraj Kandpal <suraj.kandpal@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@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.

Cc: Imre for input

Maybe pass the timeout to hsw_wait_for_power_well_enable() as parameter?
Other ideas?

BR,
Jani.

>
> 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

-- 
Jani Nikula, Intel Open Source Graphics Center