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drm/i915: Avoid potential division-by-zero in computing CS timestamp period 

Since we use a HW readback or estimation of the CS timestamp frequency,
sometimes it may result in 0. Avoid the division-by-zero in computing
its reciprocal, the timestamp period.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200216161746.500258-1-chris@chris-wilson.co.uk
alistair/sensors
Chris Wilson 2020-02-16 16:17:46 +00:00
parent 1883a0a465
commit d194314da0
1 changed files with 11 additions and 7 deletions
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18
drivers/gpu/drm/i915/intel_device_info.c
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@ -1044,13 +1044,17 @@ void intel_device_info_runtime_init(struct drm_i915_private *dev_priv)
}
/* Initialize command stream timestamp frequency */
runtime->cs_timestamp_frequency_khz = read_timestamp_frequency(dev_priv);
runtime->cs_timestamp_period_ns =
div_u64(1e6, runtime->cs_timestamp_frequency_khz);
drm_dbg(&dev_priv->drm,
"CS timestamp wraparound in %lldms\n",
div_u64(mul_u32_u32(runtime->cs_timestamp_period_ns, S32_MAX),
USEC_PER_SEC));
runtime->cs_timestamp_frequency_khz =
read_timestamp_frequency(dev_priv);
if (runtime->cs_timestamp_frequency_khz) {
runtime->cs_timestamp_period_ns =
div_u64(1e6, runtime->cs_timestamp_frequency_khz);
drm_dbg(&dev_priv->drm,
"CS timestamp wraparound in %lldms\n",
div_u64(mul_u32_u32(runtime->cs_timestamp_period_ns,
S32_MAX),
USEC_PER_SEC));
}
}
void intel_driver_caps_print(const struct intel_driver_caps *caps,