From dd2db2dc4bd298f33dea50c80c3c11bee4e3b0a4 Mon Sep 17 00:00:00 2001
From: Daniel Miess <Daniel.Miess@amd.com>
Date: Tue, 17 Jan 2023 15:45:30 -0500
Subject: [PATCH] drm/amd/display: Adjust downscaling limits for dcn314
Git-commit: dd2db2dc4bd298f33dea50c80c3c11bee4e3b0a4
Patch-mainline: v6.2-rc7
References: bsc#1206843

[Why]
Lower max_downscale_ratio and ARGB888 downscale factor
to prevent cases where underflow may occur on dcn314

[How]
Set max_downscale_ratio to 400 and ARGB downscale factor
to 250 for dcn314

Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Daniel Miess <Daniel.Miess@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/amd/display/dc/dcn314/dcn314_resource.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn314/dcn314_resource.c b/drivers/gpu/drm/amd/display/dc/dcn314/dcn314_resource.c
index f9ea1e86707f..79850a68f62a 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn314/dcn314_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn314/dcn314_resource.c
@@ -874,8 +874,9 @@ static const struct dc_plane_cap plane_cap = {
 	},
 
 	// 6:1 downscaling ratio: 1000/6 = 166.666
+	// 4:1 downscaling ratio for ARGB888 to prevent underflow during P010 playback: 1000/4 = 250
 	.max_downscale_factor = {
-			.argb8888 = 167,
+			.argb8888 = 250,
 			.nv12 = 167,
 			.fp16 = 167
 	},
@@ -1763,7 +1764,7 @@ static bool dcn314_resource_construct(
 	pool->base.underlay_pipe_index = NO_UNDERLAY_PIPE;
 	pool->base.pipe_count = pool->base.res_cap->num_timing_generator;
 	pool->base.mpcc_count = pool->base.res_cap->num_timing_generator;
-	dc->caps.max_downscale_ratio = 600;
+	dc->caps.max_downscale_ratio = 400;
 	dc->caps.i2c_speed_in_khz = 100;
 	dc->caps.i2c_speed_in_khz_hdcp = 100;
 	dc->caps.max_cursor_size = 256;
-- 
2.35.3