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.
Fixes: 0564654340e2 ("drm/i915: Acquire uncore.lock over intel_uncore_wait_for_register()")
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
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 aa9d3065853c..08abb2cb7837 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1598,7 +1598,7 @@ int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv,
unsigned int slow_timeout_ms,
u32 *out_value)
{
- u32 reg_value;
+ u32 reg_value = 0;
#define done (((reg_value = I915_READ_FW(reg)) & mask) == value)
int ret;
@@ -1609,7 +1609,7 @@ 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)
--
2.5.5
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