From ff26ffa8ee267dcbd27a5d81cb21d1c41bfdb44a Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 10 May 2017 17:19:32 +0200 Subject: [PATCH] drm/i915: Fix __intel_wait_for_register_fw to not sleep in atomic The unconditionally fallback to the blocking wait_for resulted in impressive fireworks at boot-up on my snb here. Make sure if we set the slow timeout to 0 that we never ever sleep. The tail of the callchain was intel_wait_for_register -> __intel_wait_for_register_fw -> usleep_range -> BOOM It blew up in intel_crt_detect load detection code on the ADPA_CRT_HOTPLUG_FORCE_TRIGGER in the ADPA register. v2: Shut up gcc. v3: Use uninitialized_var() (Chris). Fixes: 0564654340e2 ("drm/i915: Acquire uncore.lock over intel_uncore_wait_for_register()") Cc: Chris Wilson Cc: Michal Wajdeczko Cc: Joonas Lahtinen Cc: Tvrtko Ursulin Cc: Daniel Vetter Cc: Jani Nikula Reviewed-by: Chris Wilson Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1494429572-15118-1-git-send-email-daniel.vetter@ffwll.ch --- drivers/gpu/drm/i915/intel_uncore.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index 2c628df..08d7d08 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -1610,7 +1610,7 @@ int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv, unsigned int slow_timeout_ms, u32 *out_value) { - u32 reg_value; + u32 uninitialized_var(reg_value); #define done (((reg_value = I915_READ_FW(reg)) & mask) == value) int ret; @@ -1621,7 +1621,7 @@ int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv, ret = -ETIMEDOUT; if (fast_timeout_us && fast_timeout_us <= 20000) ret = _wait_for_atomic(done, fast_timeout_us, 0); - if (ret) + if (ret && slow_timeout_ms) ret = wait_for(done, slow_timeout_ms); if (out_value) -- 2.7.4