On Tue, Feb 21, 2017 at 06:22:02PM +0000, Chris Wilson wrote:
> 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.
>
> Fixes: 43cf3bf084ba ("drm/i915: Improved w/a for rps on Baytrail")
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.1+
> ---
> drivers/gpu/drm/i915/i915_drv.h | 2 +-
> drivers/gpu/drm/i915/i915_irq.c | 28 +++++++++-------------------
> drivers/gpu/drm/i915/intel_pm.c | 2 +-
> 3 files changed, 11 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 4e7046df1b5e..8190ab500e03 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1359,7 +1359,7 @@ 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 57fa1bf78a85..09f6a190d363 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1048,10 +1048,10 @@ 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;
>
> @@ -1077,8 +1077,7 @@ 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)
> @@ -1086,28 +1085,19 @@ 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;
> }
> @@ -4248,7 +4238,7 @@ 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;
We also need to adjust gen6_rps_pm_mask() otherwise if we are at maxfreq
we disable GEN6_PM_RP_UP_EI_EXPIRED and rely on
GEN6_PM_RP_DOWN_EI_EXPIRED, which is not now used.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre