Commit b8449c43 authored Dec 17, 2018 by Young Xiao Committed by Jani Nikula Dec 28, 2018

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 0e005888 ("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

parent 68792168

drivers/gpu/drm/i915/intel_ddi.c

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -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 *		dco_freq += (((cfgcr1_val & DPLL_CFGCR1_DCO_FRACTION_MASK) >> 9) * 24 *
	1000) / 0x8000;		1000) / 0x8000;

			if (WARN_ON(p0 == 0 \|\| p1 == 0 \|\| p2 == 0))
			return 0;

	return dco_freq / (p0 * p1 * p2 * 5);		return dco_freq / (p0 * p1 * p2 * 5);
	}		}

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