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: 43cf3bf084ba ("drm/i915: Improved w/a for rps on Baytrail")
Signed-off-by: Chris 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: Mika Kuoppala <mika.kuoppala@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b02eb362b8903d42f49b9d021432ceccc1e4276b..4d1fb620de8f3cd064da1b22576c33bb6a8265d2 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -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.

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 22ac70374ac15666cc68666a3a3f388aea9c6171..23162618c5b817ca0241096398e3d7a611cbd16a 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -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;
 
-       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;
+               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 (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;
 

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 99e09f63d4b36a2f6e1435361a80dfe7d86d353f..4db3a792c6c24dcc56461109dec0b97071c64494 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -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));