drm/i915: Add helper function for getting number of VDSC engines

Currently we are using dsc_split and bigjoiner variables for determining
amount of VDSC instances, however that might change in future, if we happen
to have more of those.
So lets pack all that logic into single function for convenience, so that
at least this isn't hardcoded throughout the whole VDSC code.

v2: - s/u8/int/ (Jani Nikula)

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230704131758.14024-2-stanislav.lisovskiy@intel.com

Author: StanFox1984

drivers/gpu/drm/i915/display/intel_vdsc.c

@@ -293,6 +293,16 @@ intel_dsc_power_domain(struct intel_crtc *crtc, enum transcoder cpu_transcoder)
 		return POWER_DOMAIN_TRANSCODER_VDSC_PW2;
 }
 
+int intel_dsc_get_num_vdsc_instances(const struct intel_crtc_state *crtc_state)
+{
+	int num_vdsc_instances = (crtc_state->dsc.dsc_split) ? 2 : 1;
+
+	if (crtc_state->bigjoiner_pipes)
+		num_vdsc_instances *= 2;
+
+	return num_vdsc_instances;
+}
+
 static void intel_dsc_pps_configure(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
@@ -303,11 +313,8 @@ static void intel_dsc_pps_configure(const struct intel_crtc_state *crtc_state)
 	u32 pps_val = 0;
 	u32 rc_buf_thresh_dword[4];
 	u32 rc_range_params_dword[8];
-	u8 num_vdsc_instances = (crtc_state->dsc.dsc_split) ? 2 : 1;
 	int i = 0;
-
-	if (crtc_state->bigjoiner_pipes)
-		num_vdsc_instances *= 2;
+	int num_vdsc_instances = intel_dsc_get_num_vdsc_instances(crtc_state);
 
 	/* Populate PICTURE_PARAMETER_SET_0 registers */
 	pps_val = DSC_VER_MAJ | vdsc_cfg->dsc_version_minor <<

drivers/gpu/drm/i915/display/intel_vdsc.h

@@ -22,6 +22,7 @@ void intel_dsc_get_config(struct intel_crtc_state *crtc_state);
 enum intel_display_power_domain
 intel_dsc_power_domain(struct intel_crtc *crtc, enum transcoder cpu_transcoder);
 struct intel_crtc *intel_dsc_get_bigjoiner_secondary(const struct intel_crtc *primary_crtc);
+int intel_dsc_get_num_vdsc_instances(const struct intel_crtc_state *crtc_state);
 void intel_dsc_dsi_pps_write(struct intel_encoder *encoder,
 			     const struct intel_crtc_state *crtc_state);
 void intel_dsc_dp_pps_write(struct intel_encoder *encoder,