Re: [Intel-gfx] [PATCH 1/7] drm/i915/display: Wait PSR2 get out of deep sleep to update pipe

["Souza, Jose" <jose.souza@intel.com>]

On Fri, 2021-09-24 at 17:35 +0300, Ville Syrjälä wrote:
> On Thu, Sep 23, 2021 at 12:46:11PM -0700, José Roberto de Souza wrote:
> > Alderlake-P was getting 'max time under evasion' messages when PSR2
> > was enabled, this is due PIPE_SCANLINE/PIPEDSL returning 0 over a
> > period of time longer than VBLANK_EVASION_TIME_US.
> > 
> > For PSR1 we had the same issue so intel_psr_wait_for_idle() was
> > implemented to wait for PSR1 to get into idle state but nothing was
> > done for PSR2.
> > 
> > For PSR2 we can't only wait for idle state as PSR2 tends to keep
> > into sleep state that means it is ready to send selective updates.
> > 
> > To do so it was necessary to add intel_wait_for_condition(), this
> > takes as parameter a function that will return true when the desidered
> > condition is meet.
> > 
> > Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> > Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> > ---
> >  .../drm/i915/display/intel_display_debugfs.c  |  3 +-
> >  drivers/gpu/drm/i915/display/intel_psr.c      | 64 ++++++++++++-------
> >  drivers/gpu/drm/i915/i915_reg.h               |  5 +-
> >  drivers/gpu/drm/i915/intel_uncore.c           | 47 ++++++++++++++
> >  drivers/gpu/drm/i915/intel_uncore.h           |  7 ++
> >  5 files changed, 100 insertions(+), 26 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > index 68f4ba8c46e75..662596adb1da6 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > @@ -303,8 +303,7 @@ psr_source_status(struct intel_dp *intel_dp, struct seq_file *m)
> >  		};
> >  		val = intel_de_read(dev_priv,
> >  				    EDP_PSR2_STATUS(intel_dp->psr.transcoder));
> > -		status_val = (val & EDP_PSR2_STATUS_STATE_MASK) >>
> > -			      EDP_PSR2_STATUS_STATE_SHIFT;
> > +		status_val = REG_FIELD_GET(EDP_PSR2_STATUS_STATE_MASK, val);
> >  		if (status_val < ARRAY_SIZE(live_status))
> >  			status = live_status[status_val];
> >  	} else {
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> > index 19a96d3c4acf4..a2e4ef42be60a 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -1796,15 +1796,33 @@ void intel_psr_post_plane_update(const struct intel_atomic_state *state)
> >  		_intel_psr_post_plane_update(state, crtc_state);
> >  }
> >  
> > -/**
> > - * psr_wait_for_idle - wait for PSR1 to idle
> > - * @intel_dp: Intel DP
> > - * @out_value: PSR status in case of failure
> > - *
> > - * Returns: 0 on success or -ETIMEOUT if PSR status does not idle.
> > - *
> > - */
> > -static int psr_wait_for_idle(struct intel_dp *intel_dp, u32 *out_value)
> > +static bool _is_psr2_read_for_pipe_update(void *data)
> > +{
> > +	struct intel_dp *intel_dp = data;
> > +	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > +	u32 val;
> > +
> > +	val = intel_uncore_read_fw(&dev_priv->uncore,
> > +				   EDP_PSR2_STATUS(intel_dp->psr.transcoder));
> > +	val &= EDP_PSR2_STATUS_STATE_MASK;
> > +
> > +	return val == EDP_PSR2_STATUS_STATE_SLEEP || val == EDP_PSR2_STATUS_STATE_IDLE;
> > +}
> > +
> > +static int _psr2_ready_for_pipe_update_locked(struct intel_dp *intel_dp)
> > +{
> > +	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > +	unsigned int fw;
> > +
> > +	fw = intel_uncore_forcewake_for_reg(&dev_priv->uncore,
> > +					    EDP_PSR2_STATUS(intel_dp->psr.transcoder),
> > +					    FW_REG_READ);
> > +	return intel_wait_for_condition(&dev_priv->uncore,
> > +					_is_psr2_read_for_pipe_update,
> > +					intel_dp, fw, 50);
> > +}
> > +
> > +static int _psr1_ready_for_pipe_update_locked(struct intel_dp *intel_dp)
> >  {
> >  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> >  
> > @@ -1814,15 +1832,13 @@ static int psr_wait_for_idle(struct intel_dp *intel_dp, u32 *out_value)
> >  	 * exit training time + 1.5 ms of aux channel handshake. 50 ms is
> >  	 * defensive enough to cover everything.
> >  	 */
> > -	return __intel_wait_for_register(&dev_priv->uncore,
> > -					 EDP_PSR_STATUS(intel_dp->psr.transcoder),
> > -					 EDP_PSR_STATUS_STATE_MASK,
> > -					 EDP_PSR_STATUS_STATE_IDLE, 2, 50,
> > -					 out_value);
> > +	return intel_de_wait_for_clear(dev_priv,
> > +				       EDP_PSR_STATUS(intel_dp->psr.transcoder),
> > +				       EDP_PSR_STATUS_STATE_MASK, 50);
> >  }
> >  
> >  /**
> > - * intel_psr_wait_for_idle - wait for PSR1 to idle
> > + * intel_psr_wait_for_idle - wait for PSR be ready for a pipe update
> >   * @new_crtc_state: new CRTC state
> >   *
> >   * This function is expected to be called from pipe_update_start() where it is
> > @@ -1839,19 +1855,23 @@ void intel_psr_wait_for_idle(const struct intel_crtc_state *new_crtc_state)
> >  	for_each_intel_encoder_mask_with_psr(&dev_priv->drm, encoder,
> >  					     new_crtc_state->uapi.encoder_mask) {
> >  		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > -		u32 psr_status;
> > +		int ret;
> >  
> >  		mutex_lock(&intel_dp->psr.lock);
> > -		if (!intel_dp->psr.enabled || intel_dp->psr.psr2_enabled) {
> > +
> > +		if (!intel_dp->psr.enabled) {
> >  			mutex_unlock(&intel_dp->psr.lock);
> >  			continue;
> >  		}
> >  
> > -		/* when the PSR1 is enabled */
> > -		if (psr_wait_for_idle(intel_dp, &psr_status))
> > -			drm_err(&dev_priv->drm,
> > -				"PSR idle timed out 0x%x, atomic update may fail\n",
> > -				psr_status);
> > +		if (intel_dp->psr.psr2_enabled)
> > +			ret = _psr2_ready_for_pipe_update_locked(intel_dp);
> > +		else
> > +			ret = _psr1_ready_for_pipe_update_locked(intel_dp);
> > +
> > +		if (ret)
> > +			drm_err(&dev_priv->drm, "PSR wait timed out, atomic update may fail\n");
> > +
> >  		mutex_unlock(&intel_dp->psr.lock);
> >  	}
> >  }
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index cad84c3b864bf..a827f5bf973cb 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -4698,8 +4698,9 @@ enum {
> >  #define _PSR2_STATUS_A			0x60940
> >  #define _PSR2_STATUS_EDP		0x6f940
> >  #define EDP_PSR2_STATUS(tran)		_MMIO_TRANS2(tran, _PSR2_STATUS_A)
> > -#define EDP_PSR2_STATUS_STATE_MASK     (0xf << 28)
> > -#define EDP_PSR2_STATUS_STATE_SHIFT    28
> > +#define EDP_PSR2_STATUS_STATE_MASK     REG_GENMASK(31, 28)
> > +#define EDP_PSR2_STATUS_STATE_SLEEP    REG_FIELD_PREP(EDP_PSR2_STATUS_STATE_MASK, 0x3)
> > +#define EDP_PSR2_STATUS_STATE_IDLE     REG_FIELD_PREP(EDP_PSR2_STATUS_STATE_MASK, 0x0)
> >  
> >  #define _PSR2_SU_STATUS_A		0x60914
> >  #define _PSR2_SU_STATUS_EDP		0x6f914
> > diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> > index 678a99de07fee..1b3ea7318c2d5 100644
> > --- a/drivers/gpu/drm/i915/intel_uncore.c
> > +++ b/drivers/gpu/drm/i915/intel_uncore.c
> > @@ -2383,6 +2383,28 @@ int __intel_wait_for_register_fw(struct intel_uncore *uncore,
> >  #undef done
> >  }
> >  
> > +static int __intel_wait_for_condition_fw(bool (*func)(void *data), void *data,
> > +					 unsigned int fast_timeout_us,
> > +					 unsigned int slow_timeout_ms)
> > +{
> > +#define done (func(data))
> > +	int ret;
> > +
> > +	/* Catch any overuse of this function */
> > +	might_sleep_if(slow_timeout_ms);
> > +	GEM_BUG_ON(fast_timeout_us > 20000);
> > +	GEM_BUG_ON(!fast_timeout_us && !slow_timeout_ms);
> > +
> > +	ret = -ETIMEDOUT;
> > +	if (fast_timeout_us && fast_timeout_us <= 20000)
> > +		ret = _wait_for_atomic(done, fast_timeout_us, 0);
> > +	if (ret && slow_timeout_ms)
> > +		ret = wait_for(done, slow_timeout_ms);
> 
> Is there a particular reason for these complicated wrappers
> instead of just using wait_for() directly?

Just replicated what __intel_wait_for_register_fw() do.
I guess the first one sleep less for cases that condition is meet in a few usecs.

> 
> > +
> > +	return ret;
> > +#undef done
> > +}
> > +
> >  /**
> >   * __intel_wait_for_register - wait until register matches expected state
> >   * @uncore: the struct intel_uncore
> > @@ -2442,6 +2464,31 @@ int __intel_wait_for_register(struct intel_uncore *uncore,
> >  	return ret;
> >  }
> >  
> > +int intel_wait_for_condition(struct intel_uncore *uncore,
> > +			     bool (*func)(void *data),
> > +			     void *data,
> > +			     unsigned int fw,
> > +			     unsigned int slow_timeout_ms)
> > +{
> > +	unsigned int fast_timeout_us = 2;
> > +	int ret;
> > +
> > +	might_sleep_if(slow_timeout_ms);
> > +
> > +	spin_lock_irq(&uncore->lock);
> > +	intel_uncore_forcewake_get__locked(uncore, fw);
> > +
> > +	ret = __intel_wait_for_condition_fw(func, data, fast_timeout_us, 0);
> > +
> > +	intel_uncore_forcewake_put__locked(uncore, fw);
> > +	spin_unlock_irq(&uncore->lock);
> > +
> > +	if (ret && slow_timeout_ms)
> > +		ret = __wait_for(, (func(data)), slow_timeout_ms * 1000, 10, 1000);
> > +
> > +	return ret;
> > +}
> > +
> >  bool intel_uncore_unclaimed_mmio(struct intel_uncore *uncore)
> >  {
> >  	bool ret;
> > diff --git a/drivers/gpu/drm/i915/intel_uncore.h b/drivers/gpu/drm/i915/intel_uncore.h
> > index 2f31c50eeae24..d6455824cbc56 100644
> > --- a/drivers/gpu/drm/i915/intel_uncore.h
> > +++ b/drivers/gpu/drm/i915/intel_uncore.h
> > @@ -282,6 +282,7 @@ int __intel_wait_for_register_fw(struct intel_uncore *uncore,
> >  				 unsigned int fast_timeout_us,
> >  				 unsigned int slow_timeout_ms,
> >  				 u32 *out_value);
> > +
> >  static inline int
> >  intel_wait_for_register_fw(struct intel_uncore *uncore,
> >  			   i915_reg_t reg,
> > @@ -293,6 +294,12 @@ intel_wait_for_register_fw(struct intel_uncore *uncore,
> >  					    2, timeout_ms, NULL);
> >  }
> >  
> > +int intel_wait_for_condition(struct intel_uncore *uncore,
> > +			     bool (*func)(void *data),
> > +			     void *data,
> > +			     unsigned int fw,
> > +			     unsigned int timeout_ms);
> > +
> >  /* register access functions */
> >  #define __raw_read(x__, s__) \
> >  static inline u##x__ __raw_uncore_read##x__(const struct intel_uncore *uncore, \
> > -- 
> > 2.33.0
>