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drm/i915: Hold gt_lock across forcewake register reads 

Along with the previous patch to make the reset operation protected by
the gt_lock as well, this ensures that all register read operations
will occur with the forcewake hardware enabled. As an added bonus,
this makes read operations more efficient by taking the spinlock only
once per read instead of twice.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Keith Packard 2012-01-06 11:48:38 -08:00
parent 286fed412a
commit c937504e2b
1 changed files with 7 additions and 2 deletions
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9
drivers/gpu/drm/i915/i915_drv.c
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@ -954,9 +954,14 @@ MODULE_LICENSE("GPL and additional rights");
u##x i915_read##x(struct drm_i915_private *dev_priv, u32 reg) { \
u##x val = 0; \
if (NEEDS_FORCE_WAKE((dev_priv), (reg))) { \
gen6_gt_force_wake_get(dev_priv); \
unsigned long irqflags; \
spin_lock_irqsave(&dev_priv->gt_lock, irqflags); \
if (dev_priv->forcewake_count == 0) \
dev_priv->display.force_wake_get(dev_priv); \
val = read##y(dev_priv->regs + reg); \
gen6_gt_force_wake_put(dev_priv); \
if (dev_priv->forcewake_count == 0) \
dev_priv->display.force_wake_put(dev_priv); \
spin_unlock_irqrestore(&dev_priv->gt_lock, irqflags); \
} else { \
val = read##y(dev_priv->regs + reg); \
} \