linux-kernel - [PATCH AUTOSEL 6.1 02/20] drm/amd/display: Update Cursor request mode to the beginning prefetch always

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Message-Id: <20250403191913.2681831-2-sashal@kernel.org>
Date: Thu,  3 Apr 2025 15:18:55 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Zhikai Zhai <zhikai.zhai@....com>,
	Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
	Zaeem Mohamed <zaeem.mohamed@....com>,
	Daniel Wheeler <daniel.wheeler@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	harry.wentland@....com,
	sunpeng.li@....com,
	christian.koenig@....com,
	airlied@...il.com,
	simona@...ll.ch,
	bhuvanachandra.pinninti@....com,
	chiahsuan.chung@....com,
	martin.leung@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.1 02/20] drm/amd/display: Update Cursor request mode to the beginning prefetch always

From: Zhikai Zhai <zhikai.zhai@....com>

[ Upstream commit 4a4077b4b63a8404efd6d37fc2926f03fb25bace ]

[Why]
The double buffer cursor registers is updated by the cursor
vupdate event. There is a gap between vupdate and cursor data
fetch if cursor fetch data reletive to cursor position.
Cursor corruption will happen if we update the cursor surface
in this gap.

[How]
Modify the cursor request mode to the beginning prefetch always
and avoid wraparound calculation issues.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@....com>
Signed-off-by: Zhikai Zhai <zhikai.zhai@....com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../amd/display/dc/dcn10/dcn10_hw_sequencer.c | 22 ++++++++-----------
 .../gpu/drm/amd/display/dc/dcn31/dcn31_hubp.c |  2 +-
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
index 416168c7dcc52..b120aa67d26c1 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
@@ -1947,20 +1947,11 @@ static void delay_cursor_until_vupdate(struct dc *dc, struct pipe_ctx *pipe_ctx)
 	dc->hwss.get_position(&pipe_ctx, 1, &position);
 	vpos = position.vertical_count;
 
-	/* Avoid wraparound calculation issues */
-	vupdate_start += stream->timing.v_total;
-	vupdate_end += stream->timing.v_total;
-	vpos += stream->timing.v_total;
-
 	if (vpos <= vupdate_start) {
 		/* VPOS is in VACTIVE or back porch. */
 		lines_to_vupdate = vupdate_start - vpos;
-	} else if (vpos > vupdate_end) {
-		/* VPOS is in the front porch. */
-		return;
 	} else {
-		/* VPOS is in VUPDATE. */
-		lines_to_vupdate = 0;
+		lines_to_vupdate = stream->timing.v_total - vpos + vupdate_start;
 	}
 
 	/* Calculate time until VUPDATE in microseconds. */
@@ -1968,13 +1959,18 @@ static void delay_cursor_until_vupdate(struct dc *dc, struct pipe_ctx *pipe_ctx)
 		stream->timing.h_total * 10000u / stream->timing.pix_clk_100hz;
 	us_to_vupdate = lines_to_vupdate * us_per_line;
 
+	/* Stall out until the cursor update completes. */
+	if (vupdate_end < vupdate_start)
+		vupdate_end += stream->timing.v_total;
+
+	/* Position is in the range of vupdate start and end*/
+	if (lines_to_vupdate > stream->timing.v_total - vupdate_end + vupdate_start)
+		us_to_vupdate = 0;
+
 	/* 70 us is a conservative estimate of cursor update time*/
 	if (us_to_vupdate > 70)
 		return;
 
-	/* Stall out until the cursor update completes. */
-	if (vupdate_end < vupdate_start)
-		vupdate_end += stream->timing.v_total;
 	us_vupdate = (vupdate_end - vupdate_start + 1) * us_per_line;
 	udelay(us_to_vupdate + us_vupdate);
 }
diff --git a/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_hubp.c b/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_hubp.c
index 39a57bcd78667..576acf2ce10dd 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_hubp.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_hubp.c
@@ -44,7 +44,7 @@ void hubp31_set_unbounded_requesting(struct hubp *hubp, bool enable)
 	struct dcn20_hubp *hubp2 = TO_DCN20_HUBP(hubp);
 
 	REG_UPDATE(DCHUBP_CNTL, HUBP_UNBOUNDED_REQ_MODE, enable);
-	REG_UPDATE(CURSOR_CONTROL, CURSOR_REQ_MODE, enable);
+	REG_UPDATE(CURSOR_CONTROL, CURSOR_REQ_MODE, 1);
 }
 
 void hubp31_soft_reset(struct hubp *hubp, bool reset)
-- 
2.39.5