Re: [Intel-gfx] [PATCH v2 3/6] drm/i915: Replace the VLV/CHV eDP reboot notifier with the .shutdown() hook

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Oct 06, 2020 at 12:29:22PM +0300, Jani Nikula wrote:
> On Thu, 01 Oct 2020, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Currently VLV/CHV use a reboot notifier to make sure the panel
> > power cycle delay isn't violated across a system reboot. Replace
> > that with the new encoder .shutdown() hook.
> >
> > And let's also stop overriding the power cycle delay with the
> > max value. No idea why the current code does that. The already
> > programmed delay should be correct.
> 
> I kind of have a little uneasy feeling about conflating these two
> changes together. I think both are objectively good changes, just not
> necessarily at once.
> 
> ISTR setting the max delay was, perhaps, somehow related to the hardware
> losing its marbles after power is cut, effectively not ensuring any of
> the delays at power-on. So it's possible we set the max here to account
> for that. Maybe. ;)
> 
> Anyway,
> 
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
> 
> on the whole.
> 
> I'm leaving it up to you, but personally I'd lean towards switching
> edp_notify_handler() to use wait_panel_power_cycle(intel_dp) first in a
> separate patch, to help with potential bisect results, and then doing
> the rest.

I don't think it would be quite that simple. We'd have to also toss
in some combination of panel_off() and vdd_off_sync() in there,
depending on whether the panel power is currently enabled or not.
Otherwise the bookkeeping needed by wait_panel_power_cycle() isn't
going to be up to date.

> 
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  .../drm/i915/display/intel_display_types.h    |  2 -
> >  drivers/gpu/drm/i915/display/intel_dp.c       | 58 +++++--------------
> >  2 files changed, 14 insertions(+), 46 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> > index 6f3e3d756383..9b9ed1a2f412 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > @@ -1319,8 +1319,6 @@ struct intel_dp {
> >  	unsigned long last_backlight_off;
> >  	ktime_t panel_power_off_time;
> >  
> > -	struct notifier_block edp_notifier;
> > -
> >  	/*
> >  	 * Pipe whose power sequencer is currently locked into
> >  	 * this port. Only relevant on VLV/CHV.
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 70e0b85442f9..e0f2e9236785 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -28,7 +28,6 @@
> >  #include <linux/export.h>
> >  #include <linux/i2c.h>
> >  #include <linux/notifier.h>
> > -#include <linux/reboot.h>
> >  #include <linux/slab.h>
> >  #include <linux/types.h>
> >  
> > @@ -1191,41 +1190,6 @@ _pp_stat_reg(struct intel_dp *intel_dp)
> >  	return regs.pp_stat;
> >  }
> >  
> > -/* Reboot notifier handler to shutdown panel power to guarantee T12 timing
> > -   This function only applicable when panel PM state is not to be tracked */
> > -static int edp_notify_handler(struct notifier_block *this, unsigned long code,
> > -			      void *unused)
> > -{
> > -	struct intel_dp *intel_dp = container_of(this, typeof(* intel_dp),
> > -						 edp_notifier);
> > -	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > -	intel_wakeref_t wakeref;
> > -
> > -	if (!intel_dp_is_edp(intel_dp) || code != SYS_RESTART)
> > -		return 0;
> > -
> > -	with_pps_lock(intel_dp, wakeref) {
> > -		if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
> > -			enum pipe pipe = vlv_power_sequencer_pipe(intel_dp);
> > -			i915_reg_t pp_ctrl_reg, pp_div_reg;
> > -			u32 pp_div;
> > -
> > -			pp_ctrl_reg = PP_CONTROL(pipe);
> > -			pp_div_reg  = PP_DIVISOR(pipe);
> > -			pp_div = intel_de_read(dev_priv, pp_div_reg);
> > -			pp_div &= PP_REFERENCE_DIVIDER_MASK;
> > -
> > -			/* 0x1F write to PP_DIV_REG sets max cycle delay */
> > -			intel_de_write(dev_priv, pp_div_reg, pp_div | 0x1F);
> > -			intel_de_write(dev_priv, pp_ctrl_reg,
> > -				       PANEL_UNLOCK_REGS);
> > -			msleep(intel_dp->panel_power_cycle_delay);
> > -		}
> > -	}
> > -
> > -	return 0;
> > -}
> > -
> >  static bool edp_have_panel_power(struct intel_dp *intel_dp)
> >  {
> >  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > @@ -6690,11 +6654,6 @@ void intel_dp_encoder_flush_work(struct drm_encoder *encoder)
> >  		 */
> >  		with_pps_lock(intel_dp, wakeref)
> >  			edp_panel_vdd_off_sync(intel_dp);
> > -
> > -		if (intel_dp->edp_notifier.notifier_call) {
> > -			unregister_reboot_notifier(&intel_dp->edp_notifier);
> > -			intel_dp->edp_notifier.notifier_call = NULL;
> > -		}
> >  	}
> >  
> >  	intel_dp_aux_fini(intel_dp);
> > @@ -6725,6 +6684,18 @@ void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder)
> >  		edp_panel_vdd_off_sync(intel_dp);
> >  }
> >  
> > +static void intel_dp_encoder_shutdown(struct intel_encoder *intel_encoder)
> > +{
> > +	struct intel_dp *intel_dp = enc_to_intel_dp(intel_encoder);
> > +	intel_wakeref_t wakeref;
> > +
> > +	if (!intel_dp_is_edp(intel_dp))
> > +		return;
> > +
> > +	with_pps_lock(intel_dp, wakeref)
> > +		wait_panel_power_cycle(intel_dp);
> > +}
> > +
> >  static void intel_edp_panel_vdd_sanitize(struct intel_dp *intel_dp)
> >  {
> >  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > @@ -7838,9 +7809,6 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
> >  	mutex_unlock(&dev->mode_config.mutex);
> >  
> >  	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
> > -		intel_dp->edp_notifier.notifier_call = edp_notify_handler;
> > -		register_reboot_notifier(&intel_dp->edp_notifier);
> > -
> >  		/*
> >  		 * Figure out the current pipe for the initial backlight setup.
> >  		 * If the current pipe isn't valid, try the PPS pipe, and if that
> > @@ -8061,6 +8029,8 @@ bool intel_dp_init(struct drm_i915_private *dev_priv,
> >  	intel_encoder->get_config = intel_dp_get_config;
> >  	intel_encoder->update_pipe = intel_panel_update_backlight;
> >  	intel_encoder->suspend = intel_dp_encoder_suspend;
> > +	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> > +		intel_encoder->shutdown = intel_dp_encoder_shutdown;
> >  	if (IS_CHERRYVIEW(dev_priv)) {
> >  		intel_encoder->pre_pll_enable = chv_dp_pre_pll_enable;
> >  		intel_encoder->pre_enable = chv_pre_enable_dp;
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center

-- 
Ville Syrjälä
Intel
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