Re: [Intel-gfx] [PATCH v2] drm/i915/dsc: abstract helpers to get bigjoiner primary/secondary crtc

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

On Fri, 11 Jun 2021, "Navare, Manasi" <manasi.d.navare@intel.com> wrote:
> On Thu, Jun 10, 2021 at 12:05:28PM +0300, Jani Nikula wrote:
>> Add a single point of truth for figuring out the primary/secondary crtc
>> for bigjoiner instead of duplicating the magic pipe +/- 1 in multiple
>> places.
>> 
>> Also fix the pipe validity checks to properly take non-contiguous pipes
>> into account. The current checks may theoretically overflow
>> i915->pipe_to_crtc_mapping[pipe], albeit with a warning, due to fused
>> off pipes, as INTEL_NUM_PIPES() returns the actual number of pipes on
>> the platform, and the check is for INTEL_NUM_PIPES() == pipe + 1.
>> 
>> Prefer primary/secondary terminology going forward.
>> 
>> v2:
>> - Improved abstractions for pipe validity etc.
>> 
>> Fixes: 8a029c113b17 ("drm/i915/dp: Modify VDSC helpers to configure DSC for Bigjoiner slave")
>> Fixes: d961eb20adb6 ("drm/i915/bigjoiner: atomic commit changes for uncompressed joiner")
>> Cc: Animesh Manna <animesh.manna@intel.com>
>> Cc: Manasi Navare <manasi.d.navare@intel.com>
>> Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> 
>> ---
>> 
>> Dropped patch 2/2 [1], as the pipes need to be adjacent for big joiner,
>> even if pipes have been fused off.
>> 
>> [1] https://patchwork.freedesktop.org/patch/msgid/20210603122842.22496-2-jani.nikula@intel.com
>> ---
>>  drivers/gpu/drm/i915/display/intel_display.c  |  7 ++--
>>  .../drm/i915/display/intel_display_types.h    |  8 ++++
>>  drivers/gpu/drm/i915/display/intel_vdsc.c     | 40 +++++++++++++------
>>  drivers/gpu/drm/i915/display/intel_vdsc.h     |  1 +
>>  4 files changed, 40 insertions(+), 16 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
>> index 362bff9beb5c..3bad4e00f7be 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
>> @@ -9618,7 +9618,6 @@ static int intel_atomic_check_bigjoiner(struct intel_atomic_state *state,
>>  					struct intel_crtc_state *old_crtc_state,
>>  					struct intel_crtc_state *new_crtc_state)
>>  {
>> -	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
>>  	struct intel_crtc_state *slave_crtc_state, *master_crtc_state;
>>  	struct intel_crtc *slave, *master;
>>  
>> @@ -9634,15 +9633,15 @@ static int intel_atomic_check_bigjoiner(struct intel_atomic_state *state,
>>  	if (!new_crtc_state->bigjoiner)
>>  		return 0;
>>  
>> -	if (1 + crtc->pipe >= INTEL_NUM_PIPES(dev_priv)) {
>> +	slave = intel_dsc_get_bigjoiner_secondary(crtc);
>> +	if (!slave) {
>>  		DRM_DEBUG_KMS("[CRTC:%d:%s] Big joiner configuration requires "
>>  			      "CRTC + 1 to be used, doesn't exist\n",
>>  			      crtc->base.base.id, crtc->base.name);
>>  		return -EINVAL;
>>  	}
>>  
>> -	slave = new_crtc_state->bigjoiner_linked_crtc =
>> -		intel_get_crtc_for_pipe(dev_priv, crtc->pipe + 1);
>> +	new_crtc_state->bigjoiner_linked_crtc = slave;
>>  	slave_crtc_state = intel_atomic_get_crtc_state(&state->base, slave);
>>  	master = crtc;
>>  	if (IS_ERR(slave_crtc_state))
>> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
>> index 15e91a99c8b9..7d64d8487fbe 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
>> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
>> @@ -1723,6 +1723,14 @@ vlv_pipe_to_channel(enum pipe pipe)
>>  	}
>>  }
>>  
>> +static inline bool intel_pipe_valid(struct drm_i915_private *i915, enum pipe pipe)
>> +{
>> +	return (pipe >= 0 &&
>> +		pipe < ARRAY_SIZE(i915->pipe_to_crtc_mapping) &&
>> +		INTEL_INFO(i915)->pipe_mask & BIT(pipe) &&
>> +		i915->pipe_to_crtc_mapping[pipe]);
>
> So no need to check INTEL_NUM_PIPES as long as the index exists in pipe_to_crtc_mappings correct?

Checking against INTEL_NUM_PIPES() is just plain wrong, because pipe may
be >= INTEL_NUM_PIPES() if pipes have been fused off.

>
>> +}
>> +
>>  static inline struct intel_crtc *
>>  intel_get_first_crtc(struct drm_i915_private *dev_priv)
>>  {
>> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> index 7121b66bf96d..85749370508c 100644
>> --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
>> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> @@ -1106,6 +1106,27 @@ static i915_reg_t dss_ctl2_reg(const struct intel_crtc_state *crtc_state)
>>  	return is_pipe_dsc(crtc_state) ? ICL_PIPE_DSS_CTL2(pipe) : DSS_CTL2;
>>  }
>>  
>> +static struct intel_crtc *
>> +_get_crtc_for_pipe(struct drm_i915_private *i915, enum pipe pipe)
>> +{
>> +	if (!intel_pipe_valid(i915, pipe))
>> +		return NULL;
>> +
>> +	return intel_get_crtc_for_pipe(i915, pipe);
>> +}
>
> Can we not include intel_pipe_valid() check in intel_get_crtc_for_pipe() so that any other function that calls intel_get_crtc_for_pipe() also
> validates the pipe ?

There's a use case for intel_dsc_get_bigjoiner_secondary() that requires
graceful error handling withouth a WARN. intel_get_crtc_for_pipe()
always WARNs on invalid pipe.

We should probably use intel_pipe_valid() in intel_get_crtc_for_pipe()
too, and WARN, but that's for another patch another time.

BR,
Jani.


>
> Manasi
>
>
>> +
>> +struct intel_crtc *
>> +intel_dsc_get_bigjoiner_secondary(const struct intel_crtc *primary_crtc)
>> +{
>> +	return _get_crtc_for_pipe(to_i915(primary_crtc->base.dev), primary_crtc->pipe + 1);
>> +}
>> +
>> +static struct intel_crtc *
>> +intel_dsc_get_bigjoiner_primary(const struct intel_crtc *secondary_crtc)
>> +{
>> +	return _get_crtc_for_pipe(to_i915(secondary_crtc->base.dev), secondary_crtc->pipe - 1);
>> +}
>> +
>>  void intel_uncompressed_joiner_enable(const struct intel_crtc_state *crtc_state)
>>  {
>>  	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>> @@ -1178,15 +1199,13 @@ void intel_uncompressed_joiner_get_config(struct intel_crtc_state *crtc_state)
>>  	dss_ctl1 = intel_de_read(dev_priv, dss_ctl1_reg(crtc_state));
>>  	if (dss_ctl1 & UNCOMPRESSED_JOINER_MASTER) {
>>  		crtc_state->bigjoiner = true;
>> -		if (!WARN_ON(INTEL_NUM_PIPES(dev_priv) == crtc->pipe + 1))
>> -			crtc_state->bigjoiner_linked_crtc =
>> -				intel_get_crtc_for_pipe(dev_priv, crtc->pipe + 1);
>> +		crtc_state->bigjoiner_linked_crtc = intel_dsc_get_bigjoiner_secondary(crtc);
>> +		drm_WARN_ON(&dev_priv->drm, !crtc_state->bigjoiner_linked_crtc);
>>  	} else if (dss_ctl1 & UNCOMPRESSED_JOINER_SLAVE) {
>>  		crtc_state->bigjoiner = true;
>>  		crtc_state->bigjoiner_slave = true;
>> -		if (!WARN_ON(crtc->pipe == PIPE_A))
>> -			crtc_state->bigjoiner_linked_crtc =
>> -				intel_get_crtc_for_pipe(dev_priv, crtc->pipe - 1);
>> +		crtc_state->bigjoiner_linked_crtc = intel_dsc_get_bigjoiner_primary(crtc);
>> +		drm_WARN_ON(&dev_priv->drm, !crtc_state->bigjoiner_linked_crtc);
>>  	}
>>  }
>>  
>> @@ -1224,14 +1243,11 @@ void intel_dsc_get_config(struct intel_crtc_state *crtc_state)
>>  
>>  		if (!(dss_ctl1 & MASTER_BIG_JOINER_ENABLE)) {
>>  			crtc_state->bigjoiner_slave = true;
>> -			if (!WARN_ON(crtc->pipe == PIPE_A))
>> -				crtc_state->bigjoiner_linked_crtc =
>> -					intel_get_crtc_for_pipe(dev_priv, crtc->pipe - 1);
>> +			crtc_state->bigjoiner_linked_crtc = intel_dsc_get_bigjoiner_primary(crtc);
>>  		} else {
>> -			if (!WARN_ON(INTEL_NUM_PIPES(dev_priv) == crtc->pipe + 1))
>> -				crtc_state->bigjoiner_linked_crtc =
>> -					intel_get_crtc_for_pipe(dev_priv, crtc->pipe + 1);
>> +			crtc_state->bigjoiner_linked_crtc = intel_dsc_get_bigjoiner_secondary(crtc);
>>  		}
>> +		drm_WARN_ON(&dev_priv->drm, !crtc_state->bigjoiner_linked_crtc);
>>  	}
>>  
>>  	/* FIXME: add more state readout as needed */
>> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.h b/drivers/gpu/drm/i915/display/intel_vdsc.h
>> index fe4d45561253..dfb1fd38deb4 100644
>> --- a/drivers/gpu/drm/i915/display/intel_vdsc.h
>> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.h
>> @@ -22,5 +22,6 @@ void intel_uncompressed_joiner_get_config(struct intel_crtc_state *crtc_state);
>>  void intel_dsc_get_config(struct intel_crtc_state *crtc_state);
>>  enum intel_display_power_domain
>>  intel_dsc_power_domain(const struct intel_crtc_state *crtc_state);
>> +struct intel_crtc *intel_dsc_get_bigjoiner_secondary(const struct intel_crtc *primary_crtc);
>>  
>>  #endif /* __INTEL_VDSC_H__ */
>> -- 
>> 2.20.1
>> 

-- 
Jani Nikula, Intel Open Source Graphics Center
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