Commit a8b1397d authored by Daniel Vetter's avatar Daniel Vetter

drm/i915: implement WaIssueDummyWriteToWakeupFromRC6

Or at least our best understanding of it.

v2: Fixup commit message and put the wa name into the comment block.
And actually update the commit, too.
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 5a35e99e
......@@ -1131,9 +1131,20 @@ static bool IS_DISPLAYREG(u32 reg)
return true;
}
static void
ilk_dummy_write(struct drm_i915_private *dev_priv)
{
/* WaIssueDummyWriteToWakeupFromRC6: Issue a dummy write to wake up the
* chip from rc6 before touching it for real. MI_MODE is masked, hence
* harmless to write 0 into. */
I915_WRITE_NOTRACE(MI_MODE, 0);
}
#define __i915_read(x, y) \
u##x i915_read##x(struct drm_i915_private *dev_priv, u32 reg) { \
u##x val = 0; \
if (IS_GEN5(dev_priv->dev)) \
ilk_dummy_write(dev_priv); \
if (NEEDS_FORCE_WAKE((dev_priv), (reg))) { \
unsigned long irqflags; \
spin_lock_irqsave(&dev_priv->gt_lock, irqflags); \
......@@ -1165,6 +1176,8 @@ void i915_write##x(struct drm_i915_private *dev_priv, u32 reg, u##x val) { \
if (NEEDS_FORCE_WAKE((dev_priv), (reg))) { \
__fifo_ret = __gen6_gt_wait_for_fifo(dev_priv); \
} \
if (IS_GEN5(dev_priv->dev)) \
ilk_dummy_write(dev_priv); \
if (IS_VALLEYVIEW(dev_priv->dev) && IS_DISPLAYREG(reg)) { \
write##y(val, dev_priv->regs + reg + 0x180000); \
} else { \
......
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