linux-kernel - [PATCH 5.9 741/757] drm/amd/display: Screen corruption on dual displays (DP+USB-C)

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Message-Id: <20201027135525.264238828@linuxfoundation.org>
Date:   Tue, 27 Oct 2020 14:56:31 +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, Qingqing Zhuo <qingqing.zhuo@....com>,
        Nicholas Kazlauskas <Nicholas.Kazlauskas@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 741/757] drm/amd/display: Screen corruption on dual displays (DP+USB-C)

From: Qingqing Zhuo <qingqing.zhuo@....com>

[ Upstream commit ce271b40a91f781af3dee985c39e841ac5148766 ]

[why]
Current pipe merge and split logic only supports cases where new
dc_state is allocated and relies on dc->current_state to gather
information from previous dc_state.

Calls to validate_bandwidth on UPDATE_TYPE_MED would cause an issue
because there is no new dc_state allocated, and data in
dc->current_state would be overwritten during pipe merge.

[how]
Only allow validate_bandwidth when new dc_state space is created.

Signed-off-by: Qingqing Zhuo <qingqing.zhuo@....com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@....com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/core/dc.c              | 2 +-
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c | 3 +++
 drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c | 3 +++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 92eb1ca1634fc..22cbfda6ab338 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -2621,7 +2621,7 @@ void dc_commit_updates_for_stream(struct dc *dc,
 
 	copy_stream_update_to_stream(dc, context, stream, stream_update);
 
-	if (update_type > UPDATE_TYPE_FAST) {
+	if (update_type >= UPDATE_TYPE_FULL) {
 		if (!dc->res_pool->funcs->validate_bandwidth(dc, context, false)) {
 			DC_ERROR("Mode validation failed for stream update!\n");
 			dc_release_state(context);
diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
index f31f48dd0da29..aaf9a99f9f045 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
@@ -3209,6 +3209,9 @@ static noinline bool dcn20_validate_bandwidth_fp(struct dc *dc,
 	context->bw_ctx.dml.soc.allow_dram_clock_one_display_vactive =
 		dc->debug.enable_dram_clock_change_one_display_vactive;
 
+	/*Unsafe due to current pipe merge and split logic*/
+	ASSERT(context != dc->current_state);
+
 	if (fast_validate) {
 		return dcn20_validate_bandwidth_internal(dc, context, true);
 	}
diff --git a/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c b/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c
index 88d41a385add8..a4f37d83d5cc9 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c
@@ -1184,6 +1184,9 @@ bool dcn21_validate_bandwidth(struct dc *dc, struct dc_state *context,
 
 	BW_VAL_TRACE_COUNT();
 
+	/*Unsafe due to current pipe merge and split logic*/
+	ASSERT(context != dc->current_state);
+
 	out = dcn20_fast_validate_bw(dc, context, pipes, &pipe_cnt, pipe_split_from, &vlevel);
 
 	if (pipe_cnt == 0)
-- 
2.25.1