linux-kernel - [PATCH 5.6 063/194] drm/amd/display: Defer cursor update around VUPDATE for all ASIC

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Date:   Mon, 18 May 2020 19:35:53 +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,
        Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
        Aric Cyr <Aric.Cyr@....com>,
        Aurabindo Pillai <aurabindo.pillai@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.6 063/194] drm/amd/display: Defer cursor update around VUPDATE for all ASIC

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

[ Upstream commit fdfd2a858590d318cfee483bd1c73e00f77533af ]

[Why]
Fixes the following scenario:

- Flip has been prepared sometime during the frame, update pending
- Cursor update happens right when VUPDATE would happen
- OPTC lock acquired, VUPDATE is blocked until next frame
- Flip is delayed potentially infinitely

With the igt@..._cursor_legacy cursor-vs-flip-legacy test we can
observe nearly *13* frames of delay for some flips on Navi.

[How]
Apply the Raven workaround generically. When close enough to VUPDATE
block cursor updates from occurring from the dc_stream_set_cursor_*
helpers.

This could perhaps be a little smarter by checking if there were
pending updates or flips earlier in the frame on the HUBP side before
applying the delay, but this should be fine for now.

This fixes the kms_cursor_legacy test.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@....com>
Reviewed-by: Aric Cyr <Aric.Cyr@....com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../gpu/drm/amd/display/dc/core/dc_stream.c   | 28 +++++++++----------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
index 6ddbb00ed37a5..8c20e9e907b2f 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
@@ -239,24 +239,24 @@ static void delay_cursor_until_vupdate(struct pipe_ctx *pipe_ctx, struct dc *dc)
 	struct dc_stream_state *stream = pipe_ctx->stream;
 	unsigned int us_per_line;
 
-	if (stream->ctx->asic_id.chip_family == FAMILY_RV &&
-			ASICREV_IS_RAVEN(stream->ctx->asic_id.hw_internal_rev)) {
+	if (!dc->hwss.get_vupdate_offset_from_vsync)
+		return;
 
-		vupdate_line = dc->hwss.get_vupdate_offset_from_vsync(pipe_ctx);
-		if (!dc_stream_get_crtc_position(dc, &stream, 1, &vpos, &nvpos))
-			return;
+	vupdate_line = dc->hwss.get_vupdate_offset_from_vsync(pipe_ctx);
+	if (!dc_stream_get_crtc_position(dc, &stream, 1, &vpos, &nvpos))
+		return;
 
-		if (vpos >= vupdate_line)
-			return;
+	if (vpos >= vupdate_line)
+		return;
 
-		us_per_line = stream->timing.h_total * 10000 / stream->timing.pix_clk_100hz;
-		lines_to_vupdate = vupdate_line - vpos;
-		us_to_vupdate = lines_to_vupdate * us_per_line;
+	us_per_line =
+		stream->timing.h_total * 10000 / stream->timing.pix_clk_100hz;
+	lines_to_vupdate = vupdate_line - vpos;
+	us_to_vupdate = lines_to_vupdate * us_per_line;
 
-		/* 70 us is a conservative estimate of cursor update time*/
-		if (us_to_vupdate < 70)
-			udelay(us_to_vupdate);
-	}
+	/* 70 us is a conservative estimate of cursor update time*/
+	if (us_to_vupdate < 70)
+		udelay(us_to_vupdate);
 #endif
 }
 
-- 
2.20.1