Re: [Intel-gfx] [PATCH] drm/i915/dp: make DSC usage logging actually useful

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Mar 30, 2022 at 12:30:19PM +0300, Jani Nikula wrote:
> Debug log when DSC is going to be used, and why, instead of
> unconditionally logging the rarely used debug option setting, which
> might not have any bearing on whether DSC is going to be used or not.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index c7f8fc654857..56c36c9ef173 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1483,6 +1483,7 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
>  		&pipe_config->hw.adjusted_mode;
>  	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
>  	struct link_config_limits limits;
> +	bool joiner_needs_dsc = false;
>  	int ret;
>  
>  	limits.min_rate = intel_dp_common_rate(intel_dp, 0);
> @@ -1518,19 +1519,23 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
>  				    adjusted_mode->crtc_clock))
>  		pipe_config->bigjoiner_pipes = GENMASK(crtc->pipe + 1, crtc->pipe);
>  
> +	/*
> +	 * Pipe joiner needs compression up to display 12 due to bandwidth
> +	 * limitation. DG2 onwards pipe joiner can be enabled without
> +	 * compression.
> +	 */
> +	joiner_needs_dsc = DISPLAY_VER(i915) < 13 && pipe_config->bigjoiner_pipes;

Could be a function to reduce the pollution.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

PS. The excessive debugs from intel_dp_dsc_get_output_bpp() are
also annoying. Would be nice if someone could do something about
that.

> +
>  	/*
>  	 * Optimize for slow and wide for everything, because there are some
>  	 * eDP 1.3 and 1.4 panels don't work well with fast and narrow.
>  	 */
>  	ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config, &limits);
>  
> -	/*
> -	 * Pipe joiner needs compression upto display12 due to BW limitation. DG2
> -	 * onwards pipe joiner can be enabled without compression.
> -	 */
> -	drm_dbg_kms(&i915->drm, "Force DSC en = %d\n", intel_dp->force_dsc_en);
> -	if (ret || intel_dp->force_dsc_en ||
> -	    (DISPLAY_VER(i915) < 13 && pipe_config->bigjoiner_pipes)) {
> +	if (ret || joiner_needs_dsc || intel_dp->force_dsc_en) {
> +		drm_dbg_kms(&i915->drm, "Try DSC (fallback=%s, joiner=%s, force=%s)\n",
> +			    str_yes_no(ret), str_yes_no(joiner_needs_dsc),
> +			    str_yes_no(intel_dp->force_dsc_en));
>  		ret = intel_dp_dsc_compute_config(intel_dp, pipe_config,
>  						  conn_state, &limits);
>  		if (ret < 0)
> -- 
> 2.30.2

-- 
Ville Syrjälä
Intel