[PATCH 01/11] drm/i915: Accurately track when we mark the hardware as idle/busy

Paulo Zanoni
2014-02-21T16:52:49Z

From: Chris Wilson <chris@chris-wilson.co.uk>

We currently call intel_mark_idle() too often, as we do so as a
side-effect of processing the request queue. However, we the calls to
intel_mark_idle() are expected to be paired with a call to
intel_mark_busy() (or else we try to idle the hardware by accessing
registers that are already disabled). Make the idle/busy tracking
explicit to prevent the multiple calls.

v2: From Paulo
- Make it compile
- Drop the __i915_add_request chunk

Reported-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
drivers/gpu/drm/i915/i915_drv.h | 8 ++++++++
drivers/gpu/drm/i915/intel_display.c | 9 +++++++++
2 files changed, 17 insertions(+)

Chris did not reply to my review comments yet, so I just went and implemented
them. We need at least an ACK form him here before merging.

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8c64831..a5caa7e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1124,6 +1124,14 @@ struct i915_gem_mm {
*/
bool interruptible;

+ /**
+ * Is the GPU currently considered idle, or busy executing userspace
+ * requests? Whilst idle, we attempt to power down the hardware and
+ * display clocks. In order to reduce the effect on performance, there
+ * is a slight delay before we do so.
+ */
+ bool busy;
+
/** Bit 6 swizzling required for X tiling */
uint32_t bit_6_swizzle_x;
/** Bit 6 swizzling required for Y tiling */
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f19e6ea..dd416f2 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8192,8 +8192,12 @@ void intel_mark_busy(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;

+ if (dev_priv->mm.busy)
+ return;
+
hsw_package_c8_gpu_busy(dev_priv);
i915_update_gfx_val(dev_priv);
+ dev_priv->mm.busy = true;
}

void intel_mark_idle(struct drm_device *dev)
@@ -8201,6 +8205,11 @@ void intel_mark_idle(struct drm_device *dev)
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_crtc *crtc;

+ if (!dev_priv->mm.busy)
+ return;
+
+ dev_priv->mm.busy = false;
+
hsw_package_c8_gpu_idle(dev_priv);

if (!i915.powersave)
--
1.8.5.3