[PATCH AUTOSEL 5.0 38/99] drm/amd/display: If one stream full updates, full update all planes

Sasha Levin sashal at kernel.org
Tue May 7 05:31:32 UTC 2019

From: David Francis <David.Francis at amd.com>

[ Upstream commit c238bfe0be9ef7420f7669a69e27c8c8f4d8a568 ]

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

current state:

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:

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:

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

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 at amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
Reviewed-by: Roman Li <Roman.Li at amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet Lakha at amd.com>
Acked-by: Nicholas Kazlauskas <Nicholas.Kazlauskas at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Sasha Levin <sashal at kernel.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 1f92e7e8e3d3..5af2ea1f201d 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -1308,6 +1308,11 @@ static enum surface_update_type det_surface_update(const struct dc *dc,
+	if (u->surface->force_full_update) {
+		update_flags->bits.full_update = 1;
+	}
 	type = get_plane_info_update_type(u);
 	elevate_update_type(&overall_type, type);
@@ -1637,6 +1642,14 @@ 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;
+		}
@@ -1680,6 +1693,12 @@ void dc_commit_updates_for_stream(struct dc *dc,
 		dc->current_state = context;
+		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 4b5bbb13ce7f..7d5656d7e460 100644
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -496,6 +496,9 @@ 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;

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