linux-kernel - [PATCH 5.4 72/80] drm/amd/display: re-enable wait in pipelock, but add timeout

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Date:   Thu, 19 Dec 2019 19:35:04 +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, Harry Wentland <harry.wentland@....com>,
        Alex Deucher <alexander.deucher@....com>
Subject: [PATCH 5.4 72/80] drm/amd/display: re-enable wait in pipelock, but add timeout

From: Alex Deucher <alexander.deucher@....com>

commit 627f75d18910b287472593a4a2c41de9a386f5a2 upstream.

Removing this causes hangs in some games, so re-add it, but add
a timeout so we don't hang while switching flip types.

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=205169
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=112266
Reviewed-by: Harry Wentland <harry.wentland@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Cc: stable@...r.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
@@ -1103,6 +1103,25 @@ void dcn20_pipe_control_lock(
 	if (pipe->plane_state != NULL)
 		flip_immediate = pipe->plane_state->flip_immediate;
 
+	if (flip_immediate && lock) {
+		const int TIMEOUT_FOR_FLIP_PENDING = 100000;
+		int i;
+
+		for (i = 0; i < TIMEOUT_FOR_FLIP_PENDING; ++i) {
+			if (!pipe->plane_res.hubp->funcs->hubp_is_flip_pending(pipe->plane_res.hubp))
+				break;
+			udelay(1);
+		}
+
+		if (pipe->bottom_pipe != NULL) {
+			for (i = 0; i < TIMEOUT_FOR_FLIP_PENDING; ++i) {
+				if (!pipe->bottom_pipe->plane_res.hubp->funcs->hubp_is_flip_pending(pipe->bottom_pipe->plane_res.hubp))
+					break;
+				udelay(1);
+			}
+		}
+	}
+
 	/* In flip immediate and pipe splitting case, we need to use GSL
 	 * for synchronization. Only do setup on locking and on flip type change.
 	 */