1 files changed, 103 insertions, 25 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
index be57088d185d..f403d8e84a8c 100644
--- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
+++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
@@ -37,6 +37,8 @@ static uint32_t dsc_policy_max_target_bpp_limit = 16;
 /* default DSC policy enables DSC only when needed */
 static bool dsc_policy_enable_dsc_when_not_needed;
 
+static bool dsc_policy_disable_dsc_stream_overhead;
+
 static bool dsc_buff_block_size_from_dpcd(int dpcd_buff_block_size, int *buff_block_size)
 {
 
@@ -250,6 +252,7 @@ static bool intersect_dsc_caps(
 	if (pixel_encoding == PIXEL_ENCODING_YCBCR422 || pixel_encoding == PIXEL_ENCODING_YCBCR420)
 		dsc_common_caps->bpp_increment_div = min(dsc_common_caps->bpp_increment_div, (uint32_t)8);
 
+	dsc_common_caps->is_dp = dsc_sink_caps->is_dp;
 	return true;
 }
 
@@ -258,12 +261,63 @@ static inline uint32_t dsc_div_by_10_round_up(uint32_t value)
 	return (value + 9) / 10;
 }
 
+static struct fixed31_32 compute_dsc_max_bandwidth_overhead(
+		const struct dc_crtc_timing *timing,
+		const int num_slices_h,
+		const bool is_dp)
+{
+	struct fixed31_32 max_dsc_overhead;
+	struct fixed31_32 refresh_rate;
+
+	if (dsc_policy_disable_dsc_stream_overhead || !is_dp)
+		return dc_fixpt_from_int(0);
+
+	/* use target bpp that can take entire target bandwidth */
+	refresh_rate = dc_fixpt_from_int(timing->pix_clk_100hz);
+	refresh_rate = dc_fixpt_div_int(refresh_rate, timing->h_total);
+	refresh_rate = dc_fixpt_div_int(refresh_rate, timing->v_total);
+	refresh_rate = dc_fixpt_mul_int(refresh_rate, 100);
+
+	max_dsc_overhead = dc_fixpt_from_int(num_slices_h);
+	max_dsc_overhead = dc_fixpt_mul_int(max_dsc_overhead, timing->v_total);
+	max_dsc_overhead = dc_fixpt_mul_int(max_dsc_overhead, 256);
+	max_dsc_overhead = dc_fixpt_div_int(max_dsc_overhead, 1000);
+	max_dsc_overhead = dc_fixpt_mul(max_dsc_overhead, refresh_rate);
+
+	return max_dsc_overhead;
+}
+
+static uint32_t compute_bpp_x16_from_target_bandwidth(
+		const uint32_t bandwidth_in_kbps,
+		const struct dc_crtc_timing *timing,
+		const uint32_t num_slices_h,
+		const uint32_t bpp_increment_div,
+		const bool is_dp)
+{
+	struct fixed31_32 overhead_in_kbps;
+	struct fixed31_32 effective_bandwidth_in_kbps;
+	struct fixed31_32 bpp_x16;
+
+	overhead_in_kbps = compute_dsc_max_bandwidth_overhead(
+				timing, num_slices_h, is_dp);
+	effective_bandwidth_in_kbps = dc_fixpt_from_int(bandwidth_in_kbps);
+	effective_bandwidth_in_kbps = dc_fixpt_sub(effective_bandwidth_in_kbps,
+			overhead_in_kbps);
+	bpp_x16 = dc_fixpt_mul_int(effective_bandwidth_in_kbps, 10);
+	bpp_x16 = dc_fixpt_div_int(bpp_x16, timing->pix_clk_100hz);
+	bpp_x16 = dc_fixpt_from_int(dc_fixpt_floor(dc_fixpt_mul_int(bpp_x16, bpp_increment_div)));
+	bpp_x16 = dc_fixpt_div_int(bpp_x16, bpp_increment_div);
+	bpp_x16 = dc_fixpt_mul_int(bpp_x16, 16);
+	return dc_fixpt_floor(bpp_x16);
+}
+
 /* Get DSC bandwidth range based on [min_bpp, max_bpp] target bitrate range, and timing's pixel clock
  * and uncompressed bandwidth.
  */
 static void get_dsc_bandwidth_range(
 		const uint32_t min_bpp_x16,
 		const uint32_t max_bpp_x16,
+		const uint32_t num_slices_h,
 		const struct dsc_enc_caps *dsc_caps,
 		const struct dc_crtc_timing *timing,
 		struct dc_dsc_bw_range *range)
@@ -272,16 +326,21 @@ static void get_dsc_bandwidth_range(
 	range->stream_kbps = dc_bandwidth_in_kbps_from_timing(timing);
 
 	/* max dsc target bpp */
-	range->max_kbps = dc_dsc_stream_bandwidth_in_kbps(timing->pix_clk_100hz, max_bpp_x16);
+	range->max_kbps = dc_dsc_stream_bandwidth_in_kbps(timing,
+			max_bpp_x16, num_slices_h, dsc_caps->is_dp);
 	range->max_target_bpp_x16 = max_bpp_x16;
 	if (range->max_kbps > range->stream_kbps) {
 		/* max dsc target bpp is capped to native bandwidth */
 		range->max_kbps = range->stream_kbps;
-		range->max_target_bpp_x16 = calc_dsc_bpp_x16(range->stream_kbps, timing->pix_clk_100hz, dsc_caps->bpp_increment_div);
+		range->max_target_bpp_x16 = compute_bpp_x16_from_target_bandwidth(
+				range->max_kbps, timing, num_slices_h,
+				dsc_caps->bpp_increment_div,
+				dsc_caps->is_dp);
 	}
 
 	/* min dsc target bpp */
-	range->min_kbps = dc_dsc_stream_bandwidth_in_kbps(timing->pix_clk_100hz, min_bpp_x16);
+	range->min_kbps = dc_dsc_stream_bandwidth_in_kbps(timing,
+			min_bpp_x16, num_slices_h, dsc_caps->is_dp);
 	range->min_target_bpp_x16 = min_bpp_x16;
 	if (range->min_kbps > range->max_kbps) {
 		/* min dsc target bpp is capped to max dsc bandwidth*/
@@ -290,7 +349,6 @@ static void get_dsc_bandwidth_range(
 	}
 }
 
-
 /* Decides if DSC should be used and calculates target bpp if it should, applying DSC policy.
  *
  * Returns:
@@ -303,6 +361,7 @@ static bool decide_dsc_target_bpp_x16(
 		const struct dsc_enc_caps *dsc_common_caps,
 		const int target_bandwidth_kbps,
 		const struct dc_crtc_timing *timing,
+		const int num_slices_h,
 		int *target_bpp_x16)
 {
 	bool should_use_dsc = false;
@@ -311,7 +370,7 @@ static bool decide_dsc_target_bpp_x16(
 	memset(&range, 0, sizeof(range));
 
 	get_dsc_bandwidth_range(policy->min_target_bpp * 16, policy->max_target_bpp * 16,
-			dsc_common_caps, timing, &range);
+			num_slices_h, dsc_common_caps, timing, &range);
 	if (!policy->enable_dsc_when_not_needed && target_bandwidth_kbps >= range.stream_kbps) {
 		/* enough bandwidth without dsc */
 		*target_bpp_x16 = 0;
@@ -327,7 +386,10 @@ static bool decide_dsc_target_bpp_x16(
 		should_use_dsc = true;
 	} else if (target_bandwidth_kbps >= range.min_kbps) {
 		/* use target bpp that can take entire target bandwidth */
-		*target_bpp_x16 = calc_dsc_bpp_x16(target_bandwidth_kbps, timing->pix_clk_100hz, dsc_common_caps->bpp_increment_div);
+		*target_bpp_x16 = compute_bpp_x16_from_target_bandwidth(
+				target_bandwidth_kbps, timing, num_slices_h,
+				dsc_common_caps->bpp_increment_div,
+				dsc_common_caps->is_dp);
 		should_use_dsc = true;
 	} else {
 		/* not enough bandwidth to fulfill minimum requirement */
@@ -531,18 +593,6 @@ static bool setup_dsc_config(
 	if (!is_dsc_possible)
 		goto done;
 
-	if (target_bandwidth_kbps > 0) {
-		is_dsc_possible = decide_dsc_target_bpp_x16(
-				&policy,
-				&dsc_common_caps,
-				target_bandwidth_kbps,
-				timing,
-				&target_bpp);
-		dsc_cfg->bits_per_pixel = target_bpp;
-	}
-	if (!is_dsc_possible)
-		goto done;
-
 	sink_per_slice_throughput_mps = 0;
 
 	// Validate available DSC settings against the mode timing
@@ -690,12 +740,26 @@ static bool setup_dsc_config(
 
 	dsc_cfg->num_slices_v = pic_height/slice_height;
 
+	if (target_bandwidth_kbps > 0) {
+		is_dsc_possible = decide_dsc_target_bpp_x16(
+				&policy,
+				&dsc_common_caps,
+				target_bandwidth_kbps,
+				timing,
+				num_slices_h,
+				&target_bpp);
+		dsc_cfg->bits_per_pixel = target_bpp;
+	}
+	if (!is_dsc_possible)
+		goto done;
+
 	// Final decission: can we do DSC or not?
 	if (is_dsc_possible) {
 		// Fill out the rest of DSC settings
 		dsc_cfg->block_pred_enable = dsc_common_caps.is_block_pred_supported;
 		dsc_cfg->linebuf_depth = dsc_common_caps.lb_bit_depth;
 		dsc_cfg->version_minor = (dsc_common_caps.dsc_version & 0xf0) >> 4;
+		dsc_cfg->is_dp = dsc_sink_caps->is_dp;
 	}
 
 done:
@@ -806,6 +870,7 @@ bool dc_dsc_parse_dsc_dpcd(const struct dc *dc, const uint8_t *dpcd_dsc_basic_da
 	dsc_sink_caps->branch_max_line_width = dpcd_dsc_branch_decoder_caps[DP_DSC_BRANCH_MAX_LINE_WIDTH - DP_DSC_BRANCH_OVERALL_THROUGHPUT_0] * 320;
 	ASSERT(dsc_sink_caps->branch_max_line_width == 0 || dsc_sink_caps->branch_max_line_width >= 5120);
 
+	dsc_sink_caps->is_dp = true;
 	return true;
 }
 
@@ -838,7 +903,8 @@ bool dc_dsc_compute_bandwidth_range(
 				dsc_min_slice_height_override, max_bpp_x16, &config);
 
 	if (is_dsc_possible)
-		get_dsc_bandwidth_range(min_bpp_x16, max_bpp_x16, &dsc_common_caps, timing, range);
+		get_dsc_bandwidth_range(min_bpp_x16, max_bpp_x16,
+				config.num_slices_h, &dsc_common_caps, timing, range);
 
 	return is_dsc_possible;
 }
@@ -864,13 +930,20 @@ bool dc_dsc_compute_config(
 	return is_dsc_possible;
 }
 
-uint32_t dc_dsc_stream_bandwidth_in_kbps(uint32_t pix_clk_100hz, uint32_t bpp_x16)
+uint32_t dc_dsc_stream_bandwidth_in_kbps(const struct dc_crtc_timing *timing,
+		uint32_t bpp_x16, uint32_t num_slices_h, bool is_dp)
 {
-	struct fixed31_32 link_bw_kbps;
-	link_bw_kbps = dc_fixpt_from_int(pix_clk_100hz);
-	link_bw_kbps = dc_fixpt_div_int(link_bw_kbps, 160);
-	link_bw_kbps = dc_fixpt_mul_int(link_bw_kbps, bpp_x16);
-	return dc_fixpt_ceil(link_bw_kbps);
+	struct fixed31_32 overhead_in_kbps;
+	struct fixed31_32 bpp;
+	struct fixed31_32 actual_bandwidth_in_kbps;
+
+	overhead_in_kbps = compute_dsc_max_bandwidth_overhead(
+			timing, num_slices_h, is_dp);
+	bpp = dc_fixpt_from_fraction(bpp_x16, 16);
+	actual_bandwidth_in_kbps = dc_fixpt_from_fraction(timing->pix_clk_100hz, 10);
+	actual_bandwidth_in_kbps = dc_fixpt_mul(actual_bandwidth_in_kbps, bpp);
+	actual_bandwidth_in_kbps = dc_fixpt_add(actual_bandwidth_in_kbps, overhead_in_kbps);
+	return dc_fixpt_ceil(actual_bandwidth_in_kbps);
 }
 
 void dc_dsc_get_policy_for_timing(const struct dc_crtc_timing *timing, uint32_t max_target_bpp_limit_override_x16, struct dc_dsc_policy *policy)
@@ -954,3 +1027,8 @@ void dc_dsc_policy_set_enable_dsc_when_not_needed(bool enable)
 {
 	dsc_policy_enable_dsc_when_not_needed = enable;
 }
+
+void dc_dsc_policy_set_disable_dsc_stream_overhead(bool disable)
+{
+	dsc_policy_disable_dsc_stream_overhead = disable;
+}