From a844f8d2a564d00d0043487d860a82d303b1a313 Mon Sep 17 00:00:00 2001
From: Alex Deucher <alexander.deucher@amd.com>
Date: Thu, 11 May 2017 13:14:14 -0400
Subject: drm/radeon/ci: disable mclk switching for high refresh rates (v2)
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commit ab03d9fe508f4e2914a8f4a9eef1b21051cacd0f upstream.

Even if the vblank period would allow it, it still seems to
be problematic on some cards.

v2: fix logic inversion (Nils)

bug: https://bugs.freedesktop.org/show_bug.cgi?id=96868

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/radeon/ci_dpm.c b/drivers/gpu/drm/radeon/ci_dpm.c
index ea36dc4..2481049 100644
--- a/drivers/gpu/drm/radeon/ci_dpm.c
+++ b/drivers/gpu/drm/radeon/ci_dpm.c
@@ -782,6 +782,12 @@ bool ci_dpm_vblank_too_short(struct radeon_device *rdev)
 	if (r600_dpm_get_vrefresh(rdev) > 120)
 		return true;
 
+	/* disable mclk switching if the refresh is >120Hz, even if the
+        * blanking period would allow it
+        */
+	if (r600_dpm_get_vrefresh(rdev) > 120)
+		return true;
+
 	if (vblank_time < switch_limit)
 		return true;
 	else
-- 
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