From b8449c43c95b5ea40ced8824d4ddea997f77b911 Mon Sep 17 00:00:00 2001
From: Young Xiao <YangX92@hotmail.com>
Date: Mon, 17 Dec 2018 12:23:03 +0000
Subject: [PATCH] drm/i915: avoid division by zero on skl_calc_wrpll_link
If for some unexpected reason the registers all read zero it's better
to WARN and return instead of dividing by zero and completely freezing
the machine.
See commit 0e005888b833 ("drm/i915: avoid division by zero on
cnl_calc_wrpll_link") for detail.
Signed-off-by: Young Xiao <YangX92@hotmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/SG2PR01MB2169F6E95BC8BB5E29477042ADBC0@SG2PR01MB2169.apcprd01.prod.exchangelabs.com
---
drivers/gpu/drm/i915/intel_ddi.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index fdf57f451b72b..2d6ed990a2327 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1296,6 +1296,9 @@ static int skl_calc_wrpll_link(struct drm_i915_private *dev_priv,
dco_freq += (((cfgcr1_val & DPLL_CFGCR1_DCO_FRACTION_MASK) >> 9) * 24 *
1000) / 0x8000;
+ if (WARN_ON(p0 == 0 || p1 == 0 || p2 == 0))
+ return 0;
+
return dco_freq / (p0 * p1 * p2 * 5);
}
--
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