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drm/i915: reference counted forcewake 

Provide a reference count to track the forcewake state of the GPU and
give a safe mechanism for userspace to wake the GT. This also potentially
saves a UC read if the GT is known to be awake already.

The reference count is atomic, but the register access and hardware wake
sequence is protected by struct_mutex.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
This commit is contained in:
Ben Widawsky 2011-04-25 11:23:07 -07:00 committed by Keith Packard
parent b7287d8054
commit fcca792629
5 changed files with 41 additions and 13 deletions
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4
drivers/gpu/drm/i915/i915_debugfs.c
View File

@ -874,7 +874,7 @@ static int i915_cur_delayinfo(struct seq_file *m, void *unused)
int max_freq;
/* RPSTAT1 is in the GT power well */
__gen6_gt_force_wake_get(dev_priv);
gen6_gt_force_wake_get(dev_priv);
rpstat = I915_READ(GEN6_RPSTAT1);
rpupei = I915_READ(GEN6_RP_CUR_UP_EI);
@ -919,7 +919,7 @@ static int i915_cur_delayinfo(struct seq_file *m, void *unused)
seq_printf(m, "Max non-overclocked (RP0) frequency: %dMHz\n",
max_freq * 50);
__gen6_gt_force_wake_put(dev_priv);
gen6_gt_force_wake_put(dev_priv);
} else {
seq_printf(m, "no P-state info available\n");
}

30
drivers/gpu/drm/i915/i915_drv.c
View File

@ -263,7 +263,7 @@ void intel_detect_pch (struct drm_device *dev)
}
}
void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
static void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
{
int count;
@ -279,12 +279,38 @@ void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
udelay(10);
}
void __gen6_gt_force_wake_put(struct drm_i915_private *dev_priv)
/*
* Generally this is called implicitly by the register read function. However,
* if some sequence requires the GT to not power down then this function should
* be called at the beginning of the sequence followed by a call to
* gen6_gt_force_wake_put() at the end of the sequence.
*/
void gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
{
WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
/* Forcewake is atomic in case we get in here without the lock */
if (atomic_add_return(1, &dev_priv->forcewake_count) == 1)
__gen6_gt_force_wake_get(dev_priv);
}
static void __gen6_gt_force_wake_put(struct drm_i915_private *dev_priv)
{
I915_WRITE_NOTRACE(FORCEWAKE, 0);
POSTING_READ(FORCEWAKE);
}
/*
* see gen6_gt_force_wake_get()
*/
void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv)
{
WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
if (atomic_dec_and_test(&dev_priv->forcewake_count))
__gen6_gt_force_wake_put(dev_priv);
}
void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv)
{
int loop = 500;

11
drivers/gpu/drm/i915/i915_drv.h
View File

@ -709,6 +709,8 @@ typedef struct drm_i915_private {
struct intel_fbdev *fbdev;
struct drm_property *broadcast_rgb_property;
atomic_t forcewake_count;
} drm_i915_private_t;
enum i915_cache_level {
@ -1329,8 +1331,8 @@ extern void intel_display_print_error_state(struct seq_file *m,
* must be set to prevent GT core from power down and stale values being
* returned.
*/
void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv);
void __gen6_gt_force_wake_put(struct drm_i915_private *dev_priv);
void gen6_gt_force_wake_get(struct drm_i915_private *dev_priv);
void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv);
void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv);
/* We give fast paths for the really cool registers */
@ -1343,15 +1345,16 @@ void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv);
static inline 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); \
gen6_gt_force_wake_get(dev_priv); \
val = read##y(dev_priv->regs + reg); \
__gen6_gt_force_wake_put(dev_priv); \
gen6_gt_force_wake_put(dev_priv); \
} else { \
val = read##y(dev_priv->regs + reg); \
} \
trace_i915_reg_rw(false, reg, val, sizeof(val)); \
return val; \
}
__i915_read(8, b)
__i915_read(16, w)
__i915_read(32, l)

1
drivers/gpu/drm/i915/i915_irq.c
View File

@ -396,7 +396,6 @@ static void gen6_pm_irq_handler(struct drm_device *dev)
I915_WRITE(GEN6_RP_INTERRUPT_LIMITS,
I915_READ(GEN6_RP_INTERRUPT_LIMITS) & ~0x3f0000);
}
}
gen6_set_rps(dev, new_delay);

8
drivers/gpu/drm/i915/intel_display.c
View File

@ -1540,7 +1540,7 @@ static void sandybridge_blit_fbc_update(struct drm_device *dev)
u32 blt_ecoskpd;
/* Make sure blitter notifies FBC of writes */
__gen6_gt_force_wake_get(dev_priv);
gen6_gt_force_wake_get(dev_priv);
blt_ecoskpd = I915_READ(GEN6_BLITTER_ECOSKPD);
blt_ecoskpd |= GEN6_BLITTER_FBC_NOTIFY <<
GEN6_BLITTER_LOCK_SHIFT;
@ -1551,7 +1551,7 @@ static void sandybridge_blit_fbc_update(struct drm_device *dev)
GEN6_BLITTER_LOCK_SHIFT);
I915_WRITE(GEN6_BLITTER_ECOSKPD, blt_ecoskpd);
POSTING_READ(GEN6_BLITTER_ECOSKPD);
__gen6_gt_force_wake_put(dev_priv);
gen6_gt_force_wake_put(dev_priv);
}
static void ironlake_enable_fbc(struct drm_crtc *crtc, unsigned long interval)
@ -6973,7 +6973,7 @@ void gen6_enable_rps(struct drm_i915_private *dev_priv)
* userspace...
*/
I915_WRITE(GEN6_RC_STATE, 0);
__gen6_gt_force_wake_get(dev_priv);
gen6_gt_force_wake_get(dev_priv);
/* disable the counters and set deterministic thresholds */
I915_WRITE(GEN6_RC_CONTROL, 0);
@ -7074,7 +7074,7 @@ void gen6_enable_rps(struct drm_i915_private *dev_priv)
/* enable all PM interrupts */
I915_WRITE(GEN6_PMINTRMSK, 0);
__gen6_gt_force_wake_put(dev_priv);
gen6_gt_force_wake_put(dev_priv);
}
void intel_enable_clock_gating(struct drm_device *dev)