Commit e0e8c7cb authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Stop using RP_DOWN_EI on Baytrail 



On Baytrail, we manually calculate busyness over the evaluation interval
to avoid issues with miscaluations with RC6 enabled. However, it turns
out that the DOWN_EI interrupt generator is completely bust - it
operates in two modes, continuous or never. Neither of which are
conducive to good behaviour. Stop unmask the DOWN_EI interrupt and just
compute everything from the UP_EI which does seem to correspond to the
desired interval.

v2: Fixup gen6_rps_pm_mask() as well
v3: Inline vlv_c0_above() to combine the now identical elapsed
calculation for up/down and simplify the threshold testing

Fixes: 43cf3bf0 ("drm/i915: Improved w/a for rps on Baytrail")
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: <stable@vger.kernel.org> # v4.1+
Link: http://patchwork.freedesktop.org/patch/msgid/20170309211232.28878-1-chris@chris-wilson.co.uk


Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
parent 8eadc19b

drivers/gpu/drm/i915/i915_drv.h

+1 −1
Original line number Diff line number Diff line
@@ -1376,7 +1376,7 @@ struct intel_gen6_power_mgmt { 
	unsigned boosts;



	/* manual wa residency calculations */

	struct intel_rps_ei up_ei, down_ei;

	struct intel_rps_ei ei;



	/*

	 * Protects RPS/RC6 register access and PCU communication.

drivers/gpu/drm/i915/i915_irq.c

+28 −45
Original line number Diff line number Diff line
@@ -1082,68 +1082,51 @@ static void vlv_c0_read(struct drm_i915_private *dev_priv, 
	ei->media_c0 = I915_READ(VLV_MEDIA_C0_COUNT);

}



static bool vlv_c0_above(struct drm_i915_private *dev_priv,

			 const struct intel_rps_ei *old,

			 const struct intel_rps_ei *now,

			 int threshold)

{

	u64 time, c0;

	unsigned int mul = 100;



	if (old->cz_clock == 0)

		return false;



	if (I915_READ(VLV_COUNTER_CONTROL) & VLV_COUNT_RANGE_HIGH)

		mul <<= 8;



	time = now->cz_clock - old->cz_clock;

	time *= threshold * dev_priv->czclk_freq;



	/* Workload can be split between render + media, e.g. SwapBuffers

	 * being blitted in X after being rendered in mesa. To account for

	 * this we need to combine both engines into our activity counter.

	 */

	c0 = now->render_c0 - old->render_c0;

	c0 += now->media_c0 - old->media_c0;

	c0 *= mul * VLV_CZ_CLOCK_TO_MILLI_SEC;



	return c0 >= time;

}



void gen6_rps_reset_ei(struct drm_i915_private *dev_priv)

{

	vlv_c0_read(dev_priv, &dev_priv->rps.down_ei);

	dev_priv->rps.up_ei = dev_priv->rps.down_ei;

	memset(&dev_priv->rps.ei, 0, sizeof(dev_priv->rps.ei));

}



static u32 vlv_wa_c0_ei(struct drm_i915_private *dev_priv, u32 pm_iir)

{

	const struct intel_rps_ei *prev = &dev_priv->rps.ei;

	struct intel_rps_ei now;

	u32 events = 0;



	if ((pm_iir & (GEN6_PM_RP_DOWN_EI_EXPIRED | GEN6_PM_RP_UP_EI_EXPIRED)) == 0)

	if ((pm_iir & GEN6_PM_RP_UP_EI_EXPIRED) == 0)

		return 0;



	vlv_c0_read(dev_priv, &now);

	if (now.cz_clock == 0)

		return 0;



	if (pm_iir & GEN6_PM_RP_DOWN_EI_EXPIRED) {

		if (!vlv_c0_above(dev_priv,

				  &dev_priv->rps.down_ei, &now,

				  dev_priv->rps.down_threshold))

			events |= GEN6_PM_RP_DOWN_THRESHOLD;

		dev_priv->rps.down_ei = now;

	}

	if (prev->cz_clock) {

		u64 time, c0;

		unsigned int mul;



		mul = VLV_CZ_CLOCK_TO_MILLI_SEC * 100; /* scale to threshold% */

		if (I915_READ(VLV_COUNTER_CONTROL) & VLV_COUNT_RANGE_HIGH)

			mul <<= 8;



		time = now.cz_clock - prev->cz_clock;

		time *= dev_priv->czclk_freq;



		/* Workload can be split between render + media,

		 * e.g. SwapBuffers being blitted in X after being rendered in

		 * mesa. To account for this we need to combine both engines

		 * into our activity counter.

		 */

		c0 = now.render_c0 - prev->render_c0;

		c0 += now.media_c0 - prev->media_c0;

		c0 *= mul;



	if (pm_iir & GEN6_PM_RP_UP_EI_EXPIRED) {

		if (vlv_c0_above(dev_priv,

				 &dev_priv->rps.up_ei, &now,

				 dev_priv->rps.up_threshold))

			events |= GEN6_PM_RP_UP_THRESHOLD;

		dev_priv->rps.up_ei = now;

		if (c0 > time * dev_priv->rps.up_threshold)

			events = GEN6_PM_RP_UP_THRESHOLD;

		else if (c0 < time * dev_priv->rps.down_threshold)

			events = GEN6_PM_RP_DOWN_THRESHOLD;

	}



	dev_priv->rps.ei = now;

	return events;

}
@@ -4283,7 +4266,7 @@ void intel_irq_init(struct drm_i915_private *dev_priv) 
	/* Let's track the enabled rps events */

	if (IS_VALLEYVIEW(dev_priv))

		/* WaGsvRC0ResidencyMethod:vlv */

		dev_priv->pm_rps_events = GEN6_PM_RP_DOWN_EI_EXPIRED | GEN6_PM_RP_UP_EI_EXPIRED;

		dev_priv->pm_rps_events = GEN6_PM_RP_UP_EI_EXPIRED;

	else

		dev_priv->pm_rps_events = GEN6_PM_RPS_EVENTS;

drivers/gpu/drm/i915/intel_pm.c

+3 −2
Original line number Diff line number Diff line
@@ -5166,8 +5166,9 @@ static u32 gen6_rps_pm_mask(struct drm_i915_private *dev_priv, u8 val) 
{

	u32 mask = 0;



	/* We use UP_EI_EXPIRED interupts for both up/down in manual mode */

	if (val > dev_priv->rps.min_freq_softlimit)

		mask |= GEN6_PM_RP_DOWN_EI_EXPIRED | GEN6_PM_RP_DOWN_THRESHOLD | GEN6_PM_RP_DOWN_TIMEOUT;

		mask |= GEN6_PM_RP_UP_EI_EXPIRED | GEN6_PM_RP_DOWN_THRESHOLD | GEN6_PM_RP_DOWN_TIMEOUT;

	if (val < dev_priv->rps.max_freq_softlimit)

		mask |= GEN6_PM_RP_UP_EI_EXPIRED | GEN6_PM_RP_UP_THRESHOLD;
@@ -5277,7 +5278,7 @@ void gen6_rps_busy(struct drm_i915_private *dev_priv) 
	if (dev_priv->rps.enabled) {

		u8 freq;



		if (dev_priv->pm_rps_events & (GEN6_PM_RP_DOWN_EI_EXPIRED | GEN6_PM_RP_UP_EI_EXPIRED))

		if (dev_priv->pm_rps_events & GEN6_PM_RP_UP_EI_EXPIRED)

			gen6_rps_reset_ei(dev_priv);

		I915_WRITE(GEN6_PMINTRMSK,

			   gen6_rps_pm_mask(dev_priv, dev_priv->rps.cur_freq));

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