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

["Navare, Manasi" <manasi.d.navare@intel.com>]

On Thu, Jun 03, 2021 at 06:49:23AM -0700, Manna, Animesh wrote:
> 
> 
> > -----Original Message-----
> > From: Jani Nikula <jani.nikula@linux.intel.com>
> > Sent: Thursday, June 3, 2021 6:03 PM
> > To: Roper, Matthew D <matthew.d.roper@intel.com>; intel-
> > gfx@lists.freedesktop.org
> > Cc: Manna, Animesh <animesh.manna@intel.com>; Navare, Manasi D
> > <manasi.d.navare@intel.com>; Kulkarni, Vandita <vandita.kulkarni@intel.com>
> > Subject: Re: [Intel-gfx] [CI 15/19] drm/i915/bigjoiner: atomic commit changes
> > for uncompressed joiner
> > 
> > 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.
> 
> Agree.


> 
> > 
> > >> +		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().
> 
> Agree.

@Jani I had asked to create a separate joiner enable since having an uncompressed enable inside dsc_enable
just from the names makes it contradicting.
But sure may be with a comment before calling uncompressed_joiner_enable() it can be just called from inside dsc enable()
And instead of checking the display ver there we just use this condition:
if (crtc_state->bigjoiner && !crtc_state->dsc.compression_enable) {
	intel_uncompressed_joiner_enable(crtc_state);
	}
Since the atomic check ensures that only for ver >=13 is when we allow big joiner and no DSC combination.

Animesh, Jani does that sound good?

Manasi


> > 
> > >>  }
> > >>
> > >>  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-v
> > > andita.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.
> 
> Ok.
> Earlier the plan is to have separate functions for uncompressed joiner, but as you suggested it can be done in the same functions of compressed bigjoiner code.
> Thanks Jani for review.
> 
> Regards,
> Animesh
> 
> > 
> > >> +	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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