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From 24142cb727f054b52a70853163e4e6d7c57c15e3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Mon, 6 May 2019 19:57:52 +0200
Subject: [PATCH 1905/2940] drm/radeon: prefer lower reference dividers
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Instead of the closest reference divider prefer the lowest,
this fixes flickering issues on HP Compaq nx9420.
Bugs: https://bugs.freedesktop.org/show_bug.cgi?id=108514
Suggested-by: Paul Dufresne <dufresnep@gmail.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
---
drivers/gpu/drm/radeon/radeon_display.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 9d3ac8b981da..d8e2d7b3b836 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -921,12 +921,12 @@ static void avivo_get_fb_ref_div(unsigned nom, unsigned den, unsigned post_div,
ref_div_max = max(min(100 / post_div, ref_div_max), 1u);
/* get matching reference and feedback divider */
- *ref_div = min(max(DIV_ROUND_CLOSEST(den, post_div), 1u), ref_div_max);
+ *ref_div = min(max(den/post_div, 1u), ref_div_max);
*fb_div = DIV_ROUND_CLOSEST(nom * *ref_div * post_div, den);
/* limit fb divider to its maximum */
if (*fb_div > fb_div_max) {
- *ref_div = DIV_ROUND_CLOSEST(*ref_div * fb_div_max, *fb_div);
+ *ref_div = (*ref_div * fb_div_max)/(*fb_div);
*fb_div = fb_div_max;
}
}
--
2.17.1
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