From a5b22b5ed88bfb848d40d3c593f5506bdb75c882 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 20 Jul 2018 12:11:02 +0100 Subject: [PATCH] drm/i915: Show stack (by WARN) for hitting forcewake errors On Sandybridge, we need a workaround to wait for the CPU thread to wake up before we are sure that we have enabled the GT power well. However, we do see the errors being reported and failed reads returning spurious results. To try and capture more details as it fails, promote the error into a WARN so we grab the stacktrace, and to try and reduce the frequency of error increase the timeout from 500us to 5ms. Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20180720111102.11549-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/intel_uncore.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index b892ca8396e8..284be151f645 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -283,14 +283,24 @@ fw_domains_reset(struct drm_i915_private *i915, fw_domain_reset(i915, d); } +static inline u32 gt_thread_status(struct drm_i915_private *dev_priv) +{ + u32 val; + + val = __raw_i915_read32(dev_priv, GEN6_GT_THREAD_STATUS_REG); + val &= GEN6_GT_THREAD_STATUS_CORE_MASK; + + return val; +} + static void __gen6_gt_wait_for_thread_c0(struct drm_i915_private *dev_priv) { - /* w/a for a sporadic read returning 0 by waiting for the GT + /* + * w/a for a sporadic read returning 0 by waiting for the GT * thread to wake up. */ - if (wait_for_atomic_us((__raw_i915_read32(dev_priv, GEN6_GT_THREAD_STATUS_REG) & - GEN6_GT_THREAD_STATUS_CORE_MASK) == 0, 500)) - DRM_ERROR("GT thread status wait timed out\n"); + WARN_ONCE(wait_for_atomic_us(gt_thread_status(dev_priv) == 0, 5000), + "GT thread status wait timed out\n"); } static void fw_domains_get_with_thread_status(struct drm_i915_private *dev_priv, -- 2.30.2