From 0564654340e2776843ade007c1aaa8e8f30dd147 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 11 Apr 2017 11:13:38 +0100
Subject: [PATCH] drm/i915: Acquire uncore.lock over intel_uncore_wait_for_register()
Git-commit: 0564654340e2776843ade007c1aaa8e8f30dd147
Patch-mainline: v4.13-rc1
References: FATE#322643 bsc#1055900
We acquire the forcewake and use I915_READ_FW instead for the atomic
wait within intel_uncore_wait_for_register. However, this still leaves
us vulnerable to concurrent mmio access to the register, which can cause
system hangs on gen7. The protection is to acquire uncore.lock around
each register, so lets add it back.
V2: Wrap __intel_wait_for_register_fw() to re-use its atomic wait_for
loop and spare adding another for ourselves.
V3: Add might_sleep() annotation
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170411101340.31994-3-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/i915/intel_uncore.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1662,14 +1662,22 @@ int intel_wait_for_register(struct drm_i
u32 value,
unsigned int timeout_ms)
{
-
unsigned fw =
intel_uncore_forcewake_for_reg(dev_priv, reg, FW_REG_READ);
int ret;
- intel_uncore_forcewake_get(dev_priv, fw);
- ret = wait_for_us((I915_READ_FW(reg) & mask) == value, 2);
- intel_uncore_forcewake_put(dev_priv, fw);
+ might_sleep();
+
+ spin_lock_irq(&dev_priv->uncore.lock);
+ intel_uncore_forcewake_get__locked(dev_priv, fw);
+
+ ret = __intel_wait_for_register_fw(dev_priv,
+ reg, mask, value,
+ 2, 0, NULL);
+
+ intel_uncore_forcewake_put__locked(dev_priv, fw);
+ spin_unlock_irq(&dev_priv->uncore.lock);
+
if (ret)
ret = wait_for((I915_READ_NOTRACE(reg) & mask) == value,
timeout_ms);