[Intel-gfx] [PATCH 2/4] drm/i915: refcounts for forcewake
Ben Widawsky
ben at bwidawsk.net
Sat Apr 9 22:31:20 CEST 2011
New refcounting mechanism for forcewake. The idea is to take away the
need to hold struct_mutex for the duration of register reads, and only
need to hold it to get a reference count. A possible benefit would shave
off some time in actually waking the GPU if it's already awake (a couple
of extra register reads).
The refcounting also provides a clean way for userspace to gain access
to correct register reads.
Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
drivers/gpu/drm/i915/i915_debugfs.c | 10 ++++++++--
drivers/gpu/drm/i915/i915_drv.c | 20 ++++++++++++++++++--
drivers/gpu/drm/i915/i915_drv.h | 10 ++++++----
drivers/gpu/drm/i915/intel_display.c | 8 ++++----
4 files changed, 36 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 87c8e29..2edb8b2 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -852,6 +852,7 @@ static int i915_cur_delayinfo(struct seq_file *m, void *unused)
struct drm_info_node *node = (struct drm_info_node *) m->private;
struct drm_device *dev = node->minor->dev;
drm_i915_private_t *dev_priv = dev->dev_private;
+ int ret;
if (IS_GEN5(dev)) {
u16 rgvswctl = I915_READ16(MEMSWCTL);
@@ -873,7 +874,11 @@ 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);
+ ret = mutex_lock_interruptible(&dev->struct_mutex);
+ if (ret)
+ return ret;
+
+ gen6_gt_force_wake_get(dev_priv);
rpstat = I915_READ(GEN6_RPSTAT1);
rpupei = I915_READ(GEN6_RP_CUR_UP_EI);
@@ -918,7 +923,8 @@ 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);
+ mutex_unlock(&dev->struct_mutex);
} else {
seq_printf(m, "no P-state info available\n");
}
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index c34a8dd..ce59cd4 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -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 +279,28 @@ 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)
+void gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
+{
+ WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
+
+ if (dev_priv->forcewake_count++ == 0)
+ __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);
}
+void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv)
+{
+ WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
+
+ if (--dev_priv->forcewake_count == 0)
+ __gen6_gt_force_wake_put(dev_priv);
+}
+
void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv)
{
int loop = 500;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8981173..f024927 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -703,6 +703,8 @@ typedef struct drm_i915_private {
struct intel_fbdev *fbdev;
struct drm_property *broadcast_rgb_property;
+
+ int forcewake_count;
} drm_i915_private_t;
struct drm_i915_gem_object {
@@ -1318,8 +1320,8 @@ 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 */
@@ -1332,9 +1334,9 @@ 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); \
} \
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 432fc04..4585005 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1828,7 +1828,7 @@ 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;
@@ -1839,7 +1839,7 @@ 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)
@@ -6853,7 +6853,7 @@ 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);
@@ -6951,7 +6951,7 @@ 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)
--
1.7.3.4
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