Re: [Intel-gfx] [CI 15/19] drm/i915/bigjoiner: atomic commit changes for uncompressed joiner

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

On Thu, 03 Jun 2021, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> On Fri, 14 May 2021, Matt Roper <matthew.d.roper@intel.com> wrote:
>> From: Animesh Manna <animesh.manna@intel.com>
>>
>> Respective bit for master or slave to be set for uncompressed
>> bigjoiner in dss_ctl1 register.
>
> I was looking at the changes here due to a static checker complaint, and
> I think there are a number of issues here. Some more serious than
> others, and some predate the patch.
>
> Comments inline.
>
>> Cc: Manasi Navare <manasi.d.navare@intel.com>
>> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
>> Signed-off-by: Clinton Taylor <Clinton.A.Taylor@intel.com>
>> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
>> Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
>> ---
>>  drivers/gpu/drm/i915/display/intel_display.c |  6 +++
>>  drivers/gpu/drm/i915/display/intel_vdsc.c    | 40 +++++++++++++++++++-
>>  drivers/gpu/drm/i915/display/intel_vdsc.h    |  2 +
>>  drivers/gpu/drm/i915/i915_reg.h              |  2 +
>>  4 files changed, 49 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
>> index b5fd721137d3..422b59ebf6dc 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
>> @@ -3411,6 +3411,7 @@ static void icl_ddi_bigjoiner_pre_enable(struct intel_atomic_state *state,
>>  					 const struct intel_crtc_state *crtc_state)
>>  {
>>  	struct intel_crtc *master = to_intel_crtc(crtc_state->uapi.crtc);
>> +	struct drm_i915_private *dev_priv = to_i915(master->base.dev);
>>  	struct intel_crtc_state *master_crtc_state;
>>  	struct drm_connector_state *conn_state;
>>  	struct drm_connector *conn;
>> @@ -3444,6 +3445,9 @@ static void icl_ddi_bigjoiner_pre_enable(struct intel_atomic_state *state,
>>  		/* and DSC on slave */
>>  		intel_dsc_enable(NULL, crtc_state);
>>  	}
>> +
>> +	if (DISPLAY_VER(dev_priv) >= 13)

I don't think we should add these checks here. Make sure the crtc_state
only has the relevant stuff enabled if the platform supports it. Don't
duplicate the checks.

>> +		intel_uncompressed_joiner_enable(crtc_state);

As this is always called after intel_dsc_enable(), I think it would make
sense to move this within intel_dsc_enable().

>>  }
>>  
>>  static void hsw_crtc_enable(struct intel_atomic_state *state,
>> @@ -6250,6 +6254,8 @@ static bool hsw_get_pipe_config(struct intel_crtc *crtc,
>>  	}
>>  
>>  	intel_dsc_get_config(pipe_config);
>> +	if (DISPLAY_VER(dev_priv) >= 13 && !pipe_config->dsc.compression_enable)
>> +		intel_uncompressed_joiner_get_config(pipe_config);

As this is always called after intel_dsc_get_config(), I think it would
make sense to move this within intel_dsc_get_config.

>>  
>>  	if (!active) {
>>  		/* bigjoiner slave doesn't enable transcoder */
>> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> index adcd6752f919..efc3184d8315 100644
>> --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
>> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> @@ -1021,6 +1021,22 @@ 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;
>>  }
>>  
>> +void intel_uncompressed_joiner_enable(const struct intel_crtc_state *crtc_state)
>
> Naming. Basically for any new function, the function name prefix should
> match the file name. intel_vdsc.[ch] should have functions prefixed
> intel_vdsc_*(). This is where we're headed to increase clarity.
>
> intel_uncompressed_*() is something completely different. 
>
> Granted, here we already have intel_dsc_*() in intel_vdsc.c. We should
> probably stick with intel_dsc_*(). A possible function or file rename is
> not out of the question, but that's a separate matter.
>
>> +{
>> +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>> +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
>> +	u32 dss_ctl1_val = 0;
>> +
>> +	if (crtc_state->bigjoiner && !crtc_state->dsc.compression_enable) {
>> +		if (crtc_state->bigjoiner_slave)
>> +			dss_ctl1_val |= UNCOMPRESSED_JOINER_SLAVE;
>> +		else
>> +			dss_ctl1_val |= UNCOMPRESSED_JOINER_MASTER;
>> +
>> +		intel_de_write(dev_priv, dss_ctl1_reg(crtc_state), dss_ctl1_val);
>> +	}
>> +}
>> +
>>  void intel_dsc_enable(struct intel_encoder *encoder,
>>  		      const struct intel_crtc_state *crtc_state)
>>  {
>> @@ -1060,13 +1076,35 @@ void intel_dsc_disable(const struct intel_crtc_state *old_crtc_state)
>>  	struct intel_crtc *crtc = to_intel_crtc(old_crtc_state->uapi.crtc);
>>  	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
>>  
>> -	if (!old_crtc_state->dsc.compression_enable)
>> +	if (!(old_crtc_state->dsc.compression_enable &&
>> +	      old_crtc_state->bigjoiner))
>
> This fails to disable compression if we only have compression but no
> bigjoiner, which is the more common case!
>
> See also:
>
> https://gitlab.freedesktop.org/drm/intel/-/issues/3537
> https://patchwork.freedesktop.org/patch/msgid/20210603065356.15435-1-vandita.kulkarni@intel.com
>
>>  		return;
>>  
>>  	intel_de_write(dev_priv, dss_ctl1_reg(old_crtc_state), 0);
>>  	intel_de_write(dev_priv, dss_ctl2_reg(old_crtc_state), 0);
>>  }
>>  
>> +void intel_uncompressed_joiner_get_config(struct intel_crtc_state *crtc_state)
>> +{
>> +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>> +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
>> +	u32 dss_ctl1;
>> +
>> +	dss_ctl1 = intel_de_read(dev_priv, dss_ctl1_reg(crtc_state));

You can't read this without holding the power domain.

Since this is always called after intel_dsc_get_config(), I think it
would make sense to move this reading there.

>> +	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);
>> +	} 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);
>> +	}
>
> Nitpick: This duplicates a bunch of logic for figuring out master/slave.
>
> The static checker warning was about crtc->pipe + 1 usage. Since
> INTEL_NUM_PIPES() looks at the hamming weight of i915->pipe_mask, the
> checker has a hard time figuring out it does not overflow
> i915->pipe_to_crtc_mapping[] in intel_get_crtc_for_pipe().
>
> So here in intel_vdsc.c the checks are for overflowing/underflowing the
> pipe range. In intel_get_crtc_for_pipe() there's a check for the pipe
> actually existing - the pipe numbering might not be contiguous.
>
> Superficially the static checker warning is bogus, as in we won't
> overflow anything. However, deep down there are issues in the
> consistency of the checks and how to handle non-contigouous pipe
> numbering.
>
> Indeed, this does not *need* the number. We should figure out the next
> *crtc*, not the next pipe *number*, which may or may not be pipe + 1.
>
>
> BR,
> Jani.
>
>> +}
>> +
>>  void intel_dsc_get_config(struct intel_crtc_state *crtc_state)
>>  {
>>  	struct drm_dsc_config *vdsc_cfg = &crtc_state->dsc.config;
>> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.h b/drivers/gpu/drm/i915/display/intel_vdsc.h
>> index 65d301c23580..fe4d45561253 100644
>> --- a/drivers/gpu/drm/i915/display/intel_vdsc.h
>> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.h
>> @@ -12,11 +12,13 @@ struct intel_encoder;
>>  struct intel_crtc_state;
>>  
>>  bool intel_dsc_source_support(const struct intel_crtc_state *crtc_state);
>> +void intel_uncompressed_joiner_enable(const struct intel_crtc_state *crtc_state);
>>  void intel_dsc_enable(struct intel_encoder *encoder,
>>  		      const struct intel_crtc_state *crtc_state);
>>  void intel_dsc_disable(const struct intel_crtc_state *crtc_state);
>>  int intel_dsc_compute_params(struct intel_encoder *encoder,
>>  			     struct intel_crtc_state *pipe_config);
>> +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);
>> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
>> index 31bc413dbba1..dd6e0bae9573 100644
>> --- a/drivers/gpu/drm/i915/i915_reg.h
>> +++ b/drivers/gpu/drm/i915/i915_reg.h
>> @@ -11493,6 +11493,8 @@ enum skl_power_gate {
>>  #define  SPLITTER_CONFIGURATION_MASK		REG_GENMASK(26, 25)
>>  #define  SPLITTER_CONFIGURATION_2_SEGMENT	REG_FIELD_PREP(SPLITTER_CONFIGURATION_MASK, 0)
>>  #define  SPLITTER_CONFIGURATION_4_SEGMENT	REG_FIELD_PREP(SPLITTER_CONFIGURATION_MASK, 1)
>> +#define  UNCOMPRESSED_JOINER_MASTER		(1 << 21)
>> +#define  UNCOMPRESSED_JOINER_SLAVE		(1 << 20)
>>  
>>  #define _ICL_PIPE_DSS_CTL2_PB			0x78204
>>  #define _ICL_PIPE_DSS_CTL2_PC			0x78404

-- 
Jani Nikula, Intel Open Source Graphics Center
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