diff options
| author |   Paulo Zanoni <paulo.r.zanoni@intel.com> | 2017-10-05 18:38:42 -0300 |
|---|---|---|
| committer | Paulo Zanoni <paulo.r.zanoni@intel.com> | 2017-10-09 17:48:18 -0300 |
| commit | 0e005888b833ba65dcf2c7aa12958dad6b2b8618 (patch) | |
| tree | 57ff2e3bf33ff5a6fa9f938a42407ef794283bca /drivers/gpu/drm/i915/intel_ddi.c | |
| parent | drm/i915: add the BXT and CNL DPLL registers to pipe_config_compare (diff) | |
| download | linux-dev-0e005888b833ba65dcf2c7aa12958dad6b2b8618.tar.xz linux-dev-0e005888b833ba65dcf2c7aa12958dad6b2b8618.zip | |
drm/i915: avoid division by zero on cnl_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.
I don't expect this to happen in the wild with the current code, but I
accidentally triggered the division by zero while doing some debugging
in an unusual environment.
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171005213842.11423-2-paulo.r.zanoni@intel.com
Diffstat (limited to 'drivers/gpu/drm/i915/intel_ddi.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_ddi.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c index ce4b7335a78a..b307b6fe1ce3 100644 --- a/drivers/gpu/drm/i915/intel_ddi.c +++ b/drivers/gpu/drm/i915/intel_ddi.c @@ -1220,6 +1220,9 @@ static int cnl_calc_wrpll_link(struct drm_i915_private *dev_priv, dco_freq += (((cfgcr0 & DPLL_CFGCR0_DCO_FRACTION_MASK) >> DPLL_CFGCR0_DCO_FRACTION_SHIFT) * ref_clock) / 0x8000; + if (WARN_ON(p0 == 0 || p1 == 0 || p2 == 0)) + return 0; + return dco_freq / (p0 * p1 * p2 * 5); } |