[PATCH 18/20] Revert "drm/amd/display: reallocate DET for dual displays with high pixel rate ratio"

[Stylon Wang]

From: Samson Tam <samson.tam at amd.com>

Revert commit b957de69c4c8 ("drm/amd/display: reallocate DET for dual displays with high pixel rate ratio")

[Why]
Previously had modified DET allocation algorithm to allocate less DET
segments for lower pixel rate display and more DET segments for higher
pixel rate display.  But noticed it is causing underflow when higher
pixel rate display is not displaying at higher mode

[How]
Roll back change

Acked-by: Stylon Wang <stylon.wang at amd.com>
Signed-off-by: Samson Tam <samson.tam at amd.com>
Reviewed-by: Alvin Lee <Alvin.Lee2 at amd.com>
---
 .../display/dc/dcn32/dcn32_resource_helpers.c | 51 ++-----------------
 1 file changed, 5 insertions(+), 46 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource_helpers.c b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource_helpers.c
index 7eec39576e2c..4882c3684b82 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource_helpers.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource_helpers.c
@@ -255,8 +255,6 @@ bool dcn32_is_psr_capable(struct pipe_ctx *pipe)
 	return psr_capable;
 }
 
-#define DCN3_2_NEW_DET_OVERRIDE_MIN_MULTIPLIER 7
-
 /**
  * dcn32_determine_det_override(): Determine DET allocation for each pipe
  *
@@ -267,6 +265,7 @@ bool dcn32_is_psr_capable(struct pipe_ctx *pipe)
  * If there is a plane that's driven by more than 1 pipe (i.e. pipe split), then the
  * number of DET for that given plane will be split among the pipes driving that plane.
  *
+ *
  * High level algorithm:
  * 1. Split total DET among number of streams
  * 2. For each stream, split DET among the planes
@@ -274,21 +273,9 @@ bool dcn32_is_psr_capable(struct pipe_ctx *pipe)
  *    among those pipes.
  * 4. Assign the DET override to the DML pipes.
  *
- * Special cases:
- *
- * For two displays that have a large difference in pixel rate, we may experience
- *  underflow on the larger display when we divide the DET equally. For this, we
- *  will implement a modified algorithm to assign more DET to larger display.
- *
- * 1. Calculate difference in pixel rates ( multiplier ) between two displays
- * 2. If the multiplier exceeds DCN3_2_NEW_DET_OVERRIDE_MIN_MULTIPLIER, then
- *    implement the modified DET override algorithm.
- * 3. Assign smaller DET size for lower pixel display and higher DET size for
- *    higher pixel display
- *
- * @dc: Current DC state
- * @context: New DC state to be programmed
- * @pipes: Array of DML pipes
+ * @param [in]: dc: Current DC state
+ * @param [in]: context: New DC state to be programmed
+ * @param [in]: pipes: Array of DML pipes
  *
  * Return: void
  */
@@ -303,31 +290,10 @@ void dcn32_determine_det_override(struct dc *dc,
 	struct dc_plane_state *current_plane = NULL;
 	uint8_t stream_count = 0;
 
-	int phy_pix_clk_mult, lower_mode_stream_index;
-	int phy_pix_clk[MAX_PIPES] = {0};
-	bool use_new_det_override_algorithm = false;
-
 	for (i = 0; i < context->stream_count; i++) {
 		/* Don't count SubVP streams for DET allocation */
-		if (context->streams[i]->mall_stream_config.type != SUBVP_PHANTOM) {
-			phy_pix_clk[i] = context->streams[i]->phy_pix_clk;
+		if (context->streams[i]->mall_stream_config.type != SUBVP_PHANTOM)
 			stream_count++;
-		}
-	}
-
-	/* Check for special case with two displays, one with much higher pixel rate */
-	if (stream_count == 2) {
-		ASSERT((phy_pix_clk[0] > 0) && (phy_pix_clk[1] > 0));
-		if (phy_pix_clk[0] < phy_pix_clk[1]) {
-			lower_mode_stream_index = 0;
-			phy_pix_clk_mult = phy_pix_clk[1] / phy_pix_clk[0];
-		} else {
-			lower_mode_stream_index = 1;
-			phy_pix_clk_mult = phy_pix_clk[0] / phy_pix_clk[1];
-		}
-
-		if (phy_pix_clk_mult >= DCN3_2_NEW_DET_OVERRIDE_MIN_MULTIPLIER)
-			use_new_det_override_algorithm = true;
 	}
 
 	if (stream_count > 0) {
@@ -336,13 +302,6 @@ void dcn32_determine_det_override(struct dc *dc,
 			if (context->streams[i]->mall_stream_config.type == SUBVP_PHANTOM)
 				continue;
 
-			if (use_new_det_override_algorithm) {
-				if (i == lower_mode_stream_index)
-					stream_segments = 4;
-				else
-					stream_segments = 14;
-			}
-
 			if (context->stream_status[i].plane_count > 0)
 				plane_segments = stream_segments / context->stream_status[i].plane_count;
 			else
-- 
2.40.1