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

Fixes: 43cf3bf084ba ("drm/i915: Improved w/a for rps on Baytrail")
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com>
Cc: <sta...@vger.kernel.org> # v4.1+
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.h |  2 +-
 drivers/gpu/drm/i915/i915_irq.c | 28 +++++++++-------------------
 drivers/gpu/drm/i915/intel_pm.c |  5 +++--
 3 files changed, 13 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 9c5b3dd9f6f1..d70bbbd6a5fd 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1366,7 +1366,7 @@ 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.
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index bc70e2c451b2..29b10bab38b6 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1050,10 +1050,10 @@ static void vlv_c0_read(struct drm_i915_private 
*dev_priv,
 }
 
 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)
 {
+       const struct intel_rps_ei *old = &dev_priv->rps.ei;
        u64 time, c0;
        unsigned int mul = 100;
 
@@ -1079,8 +1079,7 @@ static bool vlv_c0_above(struct drm_i915_private 
*dev_priv,
 
 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)
@@ -1088,28 +1087,19 @@ static u32 vlv_wa_c0_ei(struct drm_i915_private 
*dev_priv, u32 pm_iir)
        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 (vlv_c0_above(dev_priv, &now, dev_priv->rps.up_threshold))
+               events |= GEN6_PM_RP_UP_THRESHOLD;
+       else if (!vlv_c0_above(dev_priv, &now, dev_priv->rps.down_threshold))
+               events |= GEN6_PM_RP_DOWN_THRESHOLD;
 
-       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;
-       }
+       dev_priv->rps.ei = now;
 
        return events;
 }
@@ -4250,7 +4240,7 @@ 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;
 
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index ac0cd82f61e5..56472905d782 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4916,8 +4916,9 @@ 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;
 
@@ -5027,7 +5028,7 @@ 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));
-- 
2.11.0

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