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Commit 75714940 authored by Mika Kuoppala's avatar Mika Kuoppala Committed by Mika Kuoppala
Browse files

drm/i915: Do one shot unclaimed mmio detection less frequently 



We have done unclaimed register access check in normal
(mmio_debug=0) mode once per write. This adds probability
of finding the exact sequence where we did the bad access, but
also adds burden to each write.

As we have mmio_debug available for more fine grained analysis,
give up accuracy of detecting correct spot at the first occurrence
by doing the one shot detection and arming of mmio_debug in hangcheck
and in modeset. This removes the write path performance burden.

v2: Remove gratuitous DRM_DEBUG and return value, comments (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Paulo Zanoni <przanoni@gmail.com>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450250808-14864-1-git-send-email-mika.kuoppala@intel.com
parent 55ec45c2

drivers/gpu/drm/i915/i915_drv.h

+3 −0
Original line number Diff line number Diff line
@@ -718,6 +718,8 @@ struct intel_uncore { 
		i915_reg_t reg_post;

		u32 val_reset;

	} fw_domain[FW_DOMAIN_ID_COUNT];



	int unclaimed_mmio_check;

};



/* Iterate over initialised fw domains */
@@ -2718,6 +2720,7 @@ extern void intel_uncore_early_sanitize(struct drm_device *dev, 
					bool restore_forcewake);

extern void intel_uncore_init(struct drm_device *dev);

extern bool intel_uncore_unclaimed_mmio(struct drm_i915_private *dev_priv);

extern void intel_uncore_arm_unclaimed_mmio_detection(struct drm_i915_private *dev_priv);

extern void intel_uncore_fini(struct drm_device *dev);

extern void intel_uncore_forcewake_reset(struct drm_device *dev, bool restore);

const char *intel_uncore_forcewake_domain_to_str(const enum forcewake_domain_id id);

drivers/gpu/drm/i915/i915_irq.c

+6 −5
Original line number Diff line number Diff line
@@ -2188,11 +2188,6 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg) 
	/* IRQs are synced during runtime_suspend, we don't require a wakeref */

	disable_rpm_wakeref_asserts(dev_priv);



	/* We get interrupts on unclaimed registers, so check for this before we

	 * do any I915_{READ,WRITE}. */

	if (intel_uncore_unclaimed_mmio(dev_priv))

		DRM_ERROR("Unclaimed register before interrupt\n");



	/* disable master interrupt before clearing iir  */

	de_ier = I915_READ(DEIER);

	I915_WRITE(DEIER, de_ier & ~DE_MASTER_IRQ_CONTROL);
@@ -3081,6 +3076,12 @@ static void i915_hangcheck_elapsed(struct work_struct *work) 
	 */

	DISABLE_RPM_WAKEREF_ASSERTS(dev_priv);



	/* As enabling the GPU requires fairly extensive mmio access,

	 * periodically arm the mmio checker to see if we are triggering

	 * any invalid access.

	 */

	intel_uncore_arm_unclaimed_mmio_detection(dev_priv);



	for_each_ring(ring, dev_priv, i) {

		u64 acthd;

		u32 seqno;

drivers/gpu/drm/i915/intel_display.c

+13 −0
Original line number Diff line number Diff line
@@ -13684,6 +13684,19 @@ static int intel_atomic_commit(struct drm_device *dev, 


	drm_atomic_state_free(state);



	/* As one of the primary mmio accessors, KMS has a high likelihood

	 * of triggering bugs in unclaimed access. After we finish

	 * modesetting, see if an error has been flagged, and if so

	 * enable debugging for the next modeset - and hope we catch

	 * the culprit.

	 *

	 * XXX note that we assume display power is on at this point.

	 * This might hold true now but we need to add pm helper to check

	 * unclaimed only when the hardware is on, as atomic commits

	 * can happen also when the device is completely off.

	 */

	intel_uncore_arm_unclaimed_mmio_detection(dev_priv);



	return 0;

}

drivers/gpu/drm/i915/intel_uncore.c

+18 −19
Original line number Diff line number Diff line
@@ -619,22 +619,6 @@ hsw_unclaimed_reg_debug(struct drm_i915_private *dev_priv, 
	}

}



static void

hsw_unclaimed_reg_detect(struct drm_i915_private *dev_priv)

{

	static bool mmio_debug_once = true;



	if (i915.mmio_debug || !mmio_debug_once)

		return;



	if (check_for_unclaimed_mmio(dev_priv)) {

		DRM_DEBUG("Unclaimed register detected, "

			  "enabling oneshot unclaimed register reporting. "

			  "Please use i915.mmio_debug=N for more information.\n");

		i915.mmio_debug = mmio_debug_once--;

	}

}



#define GEN2_READ_HEADER(x) \

	u##x val = 0; \

	assert_rpm_wakelock_held(dev_priv);
@@ -914,7 +898,6 @@ hsw_write##x(struct drm_i915_private *dev_priv, i915_reg_t reg, u##x val, bool t 
		gen6_gt_check_fifodbg(dev_priv); \

	} \

	hsw_unclaimed_reg_debug(dev_priv, reg, false, false); \

	hsw_unclaimed_reg_detect(dev_priv); \

	GEN6_WRITE_FOOTER; \

}
@@ -949,7 +932,6 @@ gen8_write##x(struct drm_i915_private *dev_priv, i915_reg_t reg, u##x val, bool 
		__force_wake_get(dev_priv, FORCEWAKE_RENDER); \

	__raw_i915_write##x(dev_priv, reg, val); \

	hsw_unclaimed_reg_debug(dev_priv, reg, false, false); \

	hsw_unclaimed_reg_detect(dev_priv); \

	GEN6_WRITE_FOOTER; \

}
@@ -1019,7 +1001,6 @@ gen9_write##x(struct drm_i915_private *dev_priv, i915_reg_t reg, u##x val, \ 
		__force_wake_get(dev_priv, fw_engine); \

	__raw_i915_write##x(dev_priv, reg, val); \

	hsw_unclaimed_reg_debug(dev_priv, reg, false, false); \

	hsw_unclaimed_reg_detect(dev_priv); \

	GEN6_WRITE_FOOTER; \

}
@@ -1239,6 +1220,8 @@ void intel_uncore_init(struct drm_device *dev) 
	intel_uncore_fw_domains_init(dev);

	__intel_uncore_early_sanitize(dev, false);



	dev_priv->uncore.unclaimed_mmio_check = 1;



	switch (INTEL_INFO(dev)->gen) {

	default:

	case 9:
@@ -1600,3 +1583,19 @@ bool intel_uncore_unclaimed_mmio(struct drm_i915_private *dev_priv) 
{

	return check_for_unclaimed_mmio(dev_priv);

}



void

intel_uncore_arm_unclaimed_mmio_detection(struct drm_i915_private *dev_priv)

{

	if (unlikely(i915.mmio_debug ||

		     dev_priv->uncore.unclaimed_mmio_check <= 0))

		return;



	if (unlikely(intel_uncore_unclaimed_mmio(dev_priv))) {

		DRM_DEBUG("Unclaimed register detected, "

			  "enabling oneshot unclaimed register reporting. "

			  "Please use i915.mmio_debug=N for more information.\n");

		i915.mmio_debug++;

		dev_priv->uncore.unclaimed_mmio_check--;

	}

}