linux-kernel - [PATCH AUTOSEL 6.1 45/85] drm/amd/display: Workaround to increase phantom pipe vactive in pipesplit

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Message-Id: <20221218160142.925394-45-sashal@kernel.org>
Date:   Sun, 18 Dec 2022 11:01:02 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     George Shen <george.shen@....com>, Alvin Lee <Alvin.Lee2@....com>,
        Tom Chung <chiahsuan.chung@....com>,
        Daniel Wheeler <daniel.wheeler@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>, harry.wentland@....com,
        sunpeng.li@....com, Rodrigo.Siqueira@....com,
        christian.koenig@....com, Xinhui.Pan@....com, airlied@...il.com,
        daniel@...ll.ch, jun.lei@....com, Dillon.Varone@....com,
        samson.tam@....com, rdunlap@...radead.org, David.Galiffi@....com,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.1 45/85] drm/amd/display: Workaround to increase phantom pipe vactive in pipesplit

From: George Shen <george.shen@....com>

[ Upstream commit 5b8f9deaf3b6badfc0da968e6e07ceabd19700b6 ]

[Why]
Certain high resolution displays exhibit DCC line corruption with SubVP
enabled. This is likely due to insufficient DCC meta data buffered
immediately after the mclk switch.

[How]
Add workaround to increase phantom pipe vactive height by
meta_row_height number of lines, thus increasing the amount of meta data
buffered immediately after mclk switch finishes.

Reviewed-by: Alvin Lee <Alvin.Lee2@....com>
Acked-by: Tom Chung <chiahsuan.chung@....com>
Signed-off-by: George Shen <george.shen@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c
index 2abe3967f7fb..d1bf49d207de 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c
@@ -531,9 +531,11 @@ void dcn32_set_phantom_stream_timing(struct dc *dc,
 	unsigned int i, pipe_idx;
 	struct pipe_ctx *pipe;
 	uint32_t phantom_vactive, phantom_bp, pstate_width_fw_delay_lines;
+	unsigned int num_dpp;
 	unsigned int vlevel = context->bw_ctx.dml.vba.VoltageLevel;
 	unsigned int dcfclk = context->bw_ctx.dml.vba.DCFCLKState[vlevel][context->bw_ctx.dml.vba.maxMpcComb];
 	unsigned int socclk = context->bw_ctx.dml.vba.SOCCLKPerState[vlevel];
+	struct vba_vars_st *vba = &context->bw_ctx.dml.vba;
 
 	dc_assert_fp_enabled();
 
@@ -569,6 +571,11 @@ void dcn32_set_phantom_stream_timing(struct dc *dc,
 	phantom_vactive = get_subviewport_lines_needed_in_mall(&context->bw_ctx.dml, pipes, pipe_cnt, pipe_idx) +
 				pstate_width_fw_delay_lines + dc->caps.subvp_swath_height_margin_lines;
 
+	// W/A for DCC corruption with certain high resolution timings.
+	// Determing if pipesplit is used. If so, add meta_row_height to the phantom vactive.
+	num_dpp = vba->NoOfDPP[vba->VoltageLevel][vba->maxMpcComb][vba->pipe_plane[pipe_idx]];
+	phantom_vactive += num_dpp > 1 ? vba->meta_row_height[vba->pipe_plane[pipe_idx]] : 0;
+
 	// For backporch of phantom pipe, use vstartup of the main pipe
 	phantom_bp = get_vstartup(&context->bw_ctx.dml, pipes, pipe_cnt, pipe_idx);
 
-- 
2.35.1