linux-kernel - [PATCH 5.14 032/125] drm/amd/display: Require immediate flip support for DCN3.1 planes

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Date:   Mon,  1 Nov 2021 10:16:45 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Dmytro Laktyushkin <Dmytro.Laktyushkin@....com>,
        Agustin Gutierrez Sanchez <agustin.gutierrez@....com>,
        Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
        Daniel Wheeler <daniel.wheeler@....com>,
        Alex Deucher <alexander.deucher@....com>
Subject: [PATCH 5.14 032/125] drm/amd/display: Require immediate flip support for DCN3.1 planes

From: Nicholas Kazlauskas <nicholas.kazlauskas@....com>

commit 672437486ee9da3ed0e774937e6d0dd570921b39 upstream.

[Why]
Immediate flip can be enabled dynamically and has higher BW requirements
when validating which voltage mode to use.

If we validate when it's not set then potentially DCFCLK will be too low
and we will underflow.

[How]
DM always requires support so always require it as part of DML input
parameters.

This can't be enabled unconditionally on older ASIC because it blocks
some expected modes so only target DCN3.1 for now.

Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@....com>
Acked-by: Agustin Gutierrez Sanchez <agustin.gutierrez@....com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Cc: stable@...r.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c
@@ -1591,6 +1591,13 @@ static int dcn31_populate_dml_pipes_from
 		pipe = &res_ctx->pipe_ctx[i];
 		timing = &pipe->stream->timing;
 
+		/*
+		 * Immediate flip can be set dynamically after enabling the plane.
+		 * We need to require support for immediate flip or underflow can be
+		 * intermittently experienced depending on peak b/w requirements.
+		 */
+		pipes[pipe_cnt].pipe.src.immediate_flip = true;
+
 		pipes[pipe_cnt].pipe.src.unbounded_req_mode = false;
 		pipes[pipe_cnt].pipe.src.gpuvm = true;
 		pipes[pipe_cnt].pipe.src.dcc_fraction_of_zs_req_luma = 0;