Linux (Radeon): Take care that post and ref divider don't grow too large

This commit is contained in:
fritsch 2014-04-06 08:32:47 +02:00
parent 261c08ea38
commit f5c3f90b4f

View File

@ -0,0 +1,31 @@
From 146b3e334cdbfa4bf5b5d3a4162f7b677356773d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Fri, 4 Apr 2014 13:45:42 +0200
Subject: [PATCH] drm/radeon: apply more strict limits for PLL params
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Letting post and refernce divider get to big is bad for signal stability.
Signed-off-by: Christian König <christian.koenig@amd.com>
---
drivers/gpu/drm/radeon/radeon_display.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 386cfa4..d68863e 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -937,6 +937,9 @@ void radeon_compute_pll_avivo(struct radeon_pll *pll,
}
post_div = post_div_best;
+ /* limit reference * post divider to a maximum */
+ ref_div_max = min(100 / post_div, ref_div_max);
+
/* get matching reference and feedback divider */
ref_div = max(den / post_div, 1u);
fb_div = nom;
--
1.9.1