Re: [PATCH 02/16] drm/i915/display: Prepare for dsc 3 stream splitter

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

On Mon, 21 Oct 2024, Ankit Nautiyal <ankit.k.nautiyal@intel.com> wrote:
> At the moment dsc_split represents that dsc splitter is used or not.
> With 3 DSC engines, the splitter can split into two streams or three
> streams. Make the member dsc_split as int and set that to 2 when dsc
> splitter splits to 2 stream.

Maybe also name it accordingly? "dsc split" sounds like a boolean, not
like an int.

Moreover, when you change the meaning of a member, it's often good code
hygiene to rename the member to catch any incorrect uses and to ensure
you changed them all.

>
> v2: Avoid new enum for dsc split. (Suraj)
>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/icl_dsi.c        |  2 +-
>  drivers/gpu/drm/i915/display/intel_display.c  |  2 +-
>  .../drm/i915/display/intel_display_types.h    |  2 +-
>  drivers/gpu/drm/i915/display/intel_dp.c       |  2 +-
>  drivers/gpu/drm/i915/display/intel_vdsc.c     | 20 ++++++++++++++-----
>  5 files changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
> index 87a27d91d15d..553e75cf118c 100644
> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> @@ -1595,7 +1595,7 @@ static int gen11_dsi_dsc_compute_config(struct intel_encoder *encoder,
>  
>  	/* FIXME: split only when necessary */
>  	if (crtc_state->dsc.slice_count > 1)
> -		crtc_state->dsc.dsc_split = true;
> +		crtc_state->dsc.dsc_split = 2;
>  
>  	/* FIXME: initialize from VBT */
>  	vdsc_cfg->rc_model_size = DSC_RC_MODEL_SIZE_CONST;
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index ef1436146325..9e2f0fd0558f 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -5741,7 +5741,7 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
>  	PIPE_CONF_CHECK_I(dsc.config.nsl_bpg_offset);
>  
>  	PIPE_CONF_CHECK_BOOL(dsc.compression_enable);
> -	PIPE_CONF_CHECK_BOOL(dsc.dsc_split);
> +	PIPE_CONF_CHECK_I(dsc.dsc_split);
>  	PIPE_CONF_CHECK_I(dsc.compressed_bpp_x16);
>  
>  	PIPE_CONF_CHECK_BOOL(splitter.enable);
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 2bb1fa64da2f..58f510909f4d 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1235,7 +1235,7 @@ struct intel_crtc_state {
>  	/* Display Stream compression state */
>  	struct {
>  		bool compression_enable;
> -		bool dsc_split;
> +		int dsc_split;
>  		/* Compressed Bpp in U6.4 format (first 4 bits for fractional part) */
>  		u16 compressed_bpp_x16;
>  		u8 slice_count;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 286b272aa98c..c1867c883b73 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -2409,7 +2409,7 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>  	 * then we need to use 2 VDSC instances.
>  	 */
>  	if (pipe_config->joiner_pipes || pipe_config->dsc.slice_count > 1)
> -		pipe_config->dsc.dsc_split = true;
> +		pipe_config->dsc.dsc_split = 2;
>  
>  	ret = intel_dp_dsc_compute_params(connector, pipe_config);
>  	if (ret < 0) {
> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
> index 40525f5c4c42..3bce13c21756 100644
> --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
> @@ -379,7 +379,14 @@ intel_dsc_power_domain(struct intel_crtc *crtc, enum transcoder cpu_transcoder)
>  
>  static int intel_dsc_get_vdsc_per_pipe(const struct intel_crtc_state *crtc_state)
>  {
> -	return crtc_state->dsc.dsc_split ? 2 : 1;
> +	switch (crtc_state->dsc.dsc_split) {
> +	case 2:
> +		return 2;
> +	case 0:
> +	default:
> +		break;
> +	}
> +	return 1;

Seems overly complicated.

>  }
>  
>  int intel_dsc_get_num_vdsc_instances(const struct intel_crtc_state *crtc_state)
> @@ -976,8 +983,11 @@ void intel_dsc_get_config(struct intel_crtc_state *crtc_state)
>  	if (!crtc_state->dsc.compression_enable)
>  		goto out;
>  
> -	crtc_state->dsc.dsc_split = (dss_ctl2 & RIGHT_BRANCH_VDSC_ENABLE) &&
> -		(dss_ctl1 & JOINER_ENABLE);
> +	if ((dss_ctl1 & JOINER_ENABLE) &&
> +	    (dss_ctl2 & RIGHT_BRANCH_VDSC_ENABLE))

The extra parens are unnecessary.

> +		crtc_state->dsc.dsc_split = 2;
> +	else
> +		crtc_state->dsc.dsc_split = 0;
>  
>  	intel_dsc_get_pps_config(crtc_state);
>  out:
> @@ -988,10 +998,10 @@ static void intel_vdsc_dump_state(struct drm_printer *p, int indent,
>  				  const struct intel_crtc_state *crtc_state)
>  {
>  	drm_printf_indent(p, indent,
> -			  "dsc-dss: compressed-bpp:" FXP_Q4_FMT ", slice-count: %d, split: %s\n",
> +			  "dsc-dss: compressed-bpp:" FXP_Q4_FMT ", slice-count: %d, split: %d\n",

So what does the reader think when they see "split: 1" in the logs?
Split enabled?

>  			  FXP_Q4_ARGS(crtc_state->dsc.compressed_bpp_x16),
>  			  crtc_state->dsc.slice_count,
> -			  str_yes_no(crtc_state->dsc.dsc_split));
> +			  crtc_state->dsc.dsc_split);
>  }
>  
>  void intel_vdsc_state_dump(struct drm_printer *p, int indent,

-- 
Jani Nikula, Intel