From b4004c37cd072d0bbb2fa588a40543d81dac2ba4 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Sun, 16 Feb 2020 16:17:46 +0000 Subject: [PATCH] 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 Acked-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20200216161746.500258-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/intel_device_info.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c index a97437fac8845..18d9de488593e 100644 --- a/drivers/gpu/drm/i915/intel_device_info.c +++ b/drivers/gpu/drm/i915/intel_device_info.c @@ -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, -- 2.39.5