linux-kernel - [PATCH 4.19 034/113] drm/amd/display: If one stream full updates, full update all planes

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Date:   Wed, 15 May 2019 12:55:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Francis <David.Francis@....com>,
        Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
        Roman Li <Roman.Li@....com>,
        Nicholas Kazlauskas <Nicholas.Kazlauskas@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>,
        Bhawanpreet Lakha <BhawanpreetLakha@....com>
Subject: [PATCH 4.19 034/113] drm/amd/display: If one stream full updates, full update all planes

[ Upstream commit c238bfe0be9ef7420f7669a69e27c8c8f4d8a568 ]

[Why]
On some compositors, with two monitors attached, VT terminal
switch can cause a graphical issue by the following means:

There are two streams, one for each monitor. Each stream has one
plane

current state:
	M1:S1->P1
	M2:S2->P2

The user calls for a terminal switch and a commit is made to
change both planes to linear swizzle mode. In atomic check,
a new dc_state is constructed with new planes on each stream

new state:
	M1:S1->P3
	M2:S2->P4

In commit tail, each stream is committed, one at a time. The first
stream (S1) updates properly, triggerring a full update and replacing
the state

current state:
	M1:S1->P3
	M2:S2->P4

The update for S2 comes in, but dc detects that there is no difference
between the stream and plane in the new and current states, and so
triggers a fast update. The fast update does not program swizzle,
so the second monitor is corrupted

[How]
Add a flag to dc_plane_state that forces full updates

When a stream undergoes a full update, set this flag on all changed
planes, then clear it on the current stream

Subsequent streams will get full updates as a result

Signed-off-by: David Francis <David.Francis@....com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@....com>
Reviewed-by: Roman Li <Roman.Li@....com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet Lakha@....com>
Acked-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@....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 | 19 +++++++++++++++++++
 drivers/gpu/drm/amd/display/dc/dc.h      |  3 +++
 2 files changed, 22 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index bb0cda7276058..e3f5e5d6f0c18 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -1213,6 +1213,11 @@ static enum surface_update_type det_surface_update(const struct dc *dc,
 		return UPDATE_TYPE_FULL;
 	}
 
+	if (u->surface->force_full_update) {
+		update_flags->bits.full_update = 1;
+		return UPDATE_TYPE_FULL;
+	}
+
 	type = get_plane_info_update_type(u);
 	elevate_update_type(&overall_type, type);
 
@@ -1467,6 +1472,14 @@ void dc_commit_updates_for_stream(struct dc *dc,
 		}
 
 		dc_resource_state_copy_construct(state, context);
+
+		for (i = 0; i < dc->res_pool->pipe_count; i++) {
+			struct pipe_ctx *new_pipe = &context->res_ctx.pipe_ctx[i];
+			struct pipe_ctx *old_pipe = &dc->current_state->res_ctx.pipe_ctx[i];
+
+			if (new_pipe->plane_state && new_pipe->plane_state != old_pipe->plane_state)
+				new_pipe->plane_state->force_full_update = true;
+		}
 	}
 
 
@@ -1510,6 +1523,12 @@ void dc_commit_updates_for_stream(struct dc *dc,
 		dc->current_state = context;
 		dc_release_state(old);
 
+		for (i = 0; i < dc->res_pool->pipe_count; i++) {
+			struct pipe_ctx *pipe_ctx = &context->res_ctx.pipe_ctx[i];
+
+			if (pipe_ctx->plane_state && pipe_ctx->stream == stream)
+				pipe_ctx->plane_state->force_full_update = false;
+		}
 	}
 	/*let's use current_state to update watermark etc*/
 	if (update_type >= UPDATE_TYPE_FULL)
diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h
index 6c9990bef267e..4094b4f501117 100644
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -505,6 +505,9 @@ struct dc_plane_state {
 	struct dc_plane_status status;
 	struct dc_context *ctx;
 
+	/* HACK: Workaround for forcing full reprogramming under some conditions */
+	bool force_full_update;
+
 	/* private to dc_surface.c */
 	enum dc_irq_source irq_source;
 	struct kref refcount;
-- 
2.20.1