drm/i915/cdclk: Relocate intel_vdsc_min_cdclk()

Move intel_vdsc_min_cdclk() into intel_vdsc.c from intel_cdclk.c
so that details about DSC are better contained.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241029215217.3697-11-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
index 31644780e7ab..b355c479eda3 100644
--- a/drivers/gpu/drm/i915/display/intel_vdsc.c
+++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
@@ -14,6 +14,7 @@
 #include "intel_crtc.h"
 #include "intel_de.h"
 #include "intel_display_types.h"
+#include "intel_dp.h"
 #include "intel_dsi.h"
 #include "intel_qp_tables.h"
 #include "intel_vdsc.h"
@@ -1015,3 +1016,48 @@ void intel_vdsc_state_dump(struct drm_printer *p, int indent,
 	intel_vdsc_dump_state(p, indent, crtc_state);
 	drm_dsc_dump_config(p, indent, &crtc_state->dsc.config);
 }
+
+int intel_vdsc_min_cdclk(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+	struct intel_display *display = to_intel_display(crtc);
+	int num_vdsc_instances = intel_dsc_get_num_vdsc_instances(crtc_state);
+	int min_cdclk;
+
+	if (!crtc_state->dsc.compression_enable)
+		return 0;
+
+	/*
+	 * When we decide to use only one VDSC engine, since
+	 * each VDSC operates with 1 ppc throughput, pixel clock
+	 * cannot be higher than the VDSC clock (cdclk)
+	 * If there 2 VDSC engines, then pixel clock can't be higher than
+	 * VDSC clock(cdclk) * 2 and so on.
+	 */
+	min_cdclk = DIV_ROUND_UP(crtc_state->pixel_rate, num_vdsc_instances);
+
+	if (crtc_state->joiner_pipes) {
+		int pixel_clock = intel_dp_mode_to_fec_clock(crtc_state->hw.adjusted_mode.clock);
+
+		/*
+		 * According to Bigjoiner bw check:
+		 * compressed_bpp <= PPC * CDCLK * Big joiner Interface bits / Pixel clock
+		 *
+		 * We have already computed compressed_bpp, so now compute the min CDCLK that
+		 * is required to support this compressed_bpp.
+		 *
+		 * => CDCLK >= compressed_bpp * Pixel clock / (PPC * Bigjoiner Interface bits)
+		 *
+		 * Since PPC = 2 with bigjoiner
+		 * => CDCLK >= compressed_bpp * Pixel clock  / 2 * Bigjoiner Interface bits
+		 */
+		int bigjoiner_interface_bits = DISPLAY_VER(display) >= 14 ? 36 : 24;
+		int min_cdclk_bj =
+			(fxp_q4_to_int_roundup(crtc_state->dsc.compressed_bpp_x16) *
+			 pixel_clock) / (2 * bigjoiner_interface_bits);
+
+		min_cdclk = max(min_cdclk, min_cdclk_bj);
+	}
+
+	return min_cdclk;
+}