drm/i915/dp: Separate out function to get compressed bpp with joiner

Pull the code to get joiner constraints on maximum compressed bpp into
separate function.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230817142459.89764-16-ankit.k.nautiyal@intel.com

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

@@ -740,6 +740,32 @@ u32 intel_dp_dsc_nearest_valid_bpp(struct drm_i915_private *i915, u32 bpp, u32 p
 	return bits_per_pixel;
 }
 
+static
+u32 get_max_compressed_bpp_with_joiner(struct drm_i915_private *i915,
+				       u32 mode_clock, u32 mode_hdisplay,
+				       bool bigjoiner)
+{
+	u32 max_bpp_small_joiner_ram;
+
+	/* Small Joiner Check: output bpp <= joiner RAM (bits) / Horiz. width */
+	max_bpp_small_joiner_ram = small_joiner_ram_size_bits(i915) / mode_hdisplay;
+
+	if (bigjoiner) {
+		int bigjoiner_interface_bits = DISPLAY_VER(i915) >= 14 ? 36 : 24;
+		/* With bigjoiner multiple dsc engines are used in parallel so PPC is 2 */
+		int ppc = 2;
+		u32 max_bpp_bigjoiner =
+			i915->display.cdclk.max_cdclk_freq * ppc * bigjoiner_interface_bits /
+			intel_dp_mode_to_fec_clock(mode_clock);
+
+		max_bpp_small_joiner_ram *= 2;
+
+		return min(max_bpp_small_joiner_ram, max_bpp_bigjoiner);
+	}
+
+	return max_bpp_small_joiner_ram;
+}
+
 u16 intel_dp_dsc_get_max_compressed_bpp(struct drm_i915_private *i915,
 					u32 link_clock, u32 lane_count,
 					u32 mode_clock, u32 mode_hdisplay,
@@ -748,7 +774,7 @@ u16 intel_dp_dsc_get_max_compressed_bpp(struct drm_i915_private *i915,
 					u32 pipe_bpp,
 					u32 timeslots)
 {
-	u32 bits_per_pixel, max_bpp_small_joiner_ram;
+	u32 bits_per_pixel, joiner_max_bpp;
 
 	/*
 	 * Available Link Bandwidth(Kbits/sec) = (NumberOfLanes)*
@@ -788,29 +814,9 @@ u16 intel_dp_dsc_get_max_compressed_bpp(struct drm_i915_private *i915,
 				(link_clock * lane_count * 8),
 				intel_dp_mode_to_fec_clock(mode_clock));
 
-	/* Small Joiner Check: output bpp <= joiner RAM (bits) / Horiz. width */
-	max_bpp_small_joiner_ram = small_joiner_ram_size_bits(i915) /
-		mode_hdisplay;
-
-	if (bigjoiner)
-		max_bpp_small_joiner_ram *= 2;
-
-	/*
-	 * Greatest allowed DSC BPP = MIN (output BPP from available Link BW
-	 * check, output bpp from small joiner RAM check)
-	 */
-	bits_per_pixel = min(bits_per_pixel, max_bpp_small_joiner_ram);
-
-	if (bigjoiner) {
-		int bigjoiner_interface_bits = DISPLAY_VER(i915) >= 14 ? 36 : 24;
-		/* With bigjoiner multiple dsc engines are used in parallel so PPC is 2 */
-		int ppc = 2;
-		u32 max_bpp_bigjoiner =
-			i915->display.cdclk.max_cdclk_freq * ppc * bigjoiner_interface_bits /
-			intel_dp_mode_to_fec_clock(mode_clock);
-
-		bits_per_pixel = min(bits_per_pixel, max_bpp_bigjoiner);
-	}
+	joiner_max_bpp = get_max_compressed_bpp_with_joiner(i915, mode_clock,
+							    mode_hdisplay, bigjoiner);
+	bits_per_pixel = min(bits_per_pixel, joiner_max_bpp);
 
 	bits_per_pixel = intel_dp_dsc_nearest_valid_bpp(i915, bits_per_pixel, pipe_bpp);