Re: [PATCH 8/9] drm/i915/bdw: Implement a basic PM interrupt handler

From: Ben Widawsky <ben@bwidawsk.net>
To: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Cc: intel-gfx@freedesktop.org,
	Intel GFX <intel-gfx@lists.freedesktop.org>,
	Ben Widawsky <benjamin.widawsky@intel.com>
Subject: Re: [PATCH 8/9] drm/i915/bdw: Implement a basic PM interrupt handler
Date: Mon, 17 Feb 2014 12:01:29 -0800	[thread overview]
Message-ID: <20140217200129.GB19622@bwidawsk.net> (raw)
In-Reply-To: <CABVU7+sptqY5N3+pWMK+A9m82bxF5ii=9fAfty3vtsfRPNqWPg@mail.gmail.com>

On Thu, Feb 06, 2014 at 12:15:12PM -0200, Rodrigo Vivi wrote:
> On Wed, Jan 29, 2014 at 2:25 AM, Ben Widawsky
> <benjamin.widawsky@intel.com> wrote:
> > Almost all of it is reusable from the existing code. The primary
> > difference is we need to do even less in the interrupt handler, since
> > interrupts are not shared in the same way.
> >
> > The patch is mostly a copy-paste of the existing snb+ code, with updates
> > to the relevant parts requiring changes to the interrupt handling. As
> > such it /should/ be relatively trivial. It's highly likely that I missed
> > some places where I need a gen8 version of the PM interrupts, but it has
> > become invisible to me by now.
> >
> > This patch could probably be split into adding the new functions,
> > followed by actually handling the interrupts. Since the code is
> > currently disabled (and broken) I think the patch stands better by
> > itself.
> >
> > Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> > ---
> >  drivers/gpu/drm/i915/i915_irq.c  | 80 ++++++++++++++++++++++++++++++++++++++--
> >  drivers/gpu/drm/i915/i915_reg.h  |  1 +
> >  drivers/gpu/drm/i915/intel_drv.h |  2 +
> >  drivers/gpu/drm/i915/intel_pm.c  | 39 +++++++++++++++++++-
> >  4 files changed, 117 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > index 72ade87..ab0c7ac 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -214,6 +214,53 @@ static bool ivb_can_enable_err_int(struct drm_device *dev)
> >         return true;
> >  }
> >
> > +/**
> > +  * bdw_update_pm_irq - update GT interrupt 2
> > +  * @dev_priv: driver private
> > +  * @interrupt_mask: mask of interrupt bits to update
> > +  * @enabled_irq_mask: mask of interrupt bits to enable
> > +  *
> > +  * Copied from the snb function, updated with relevant register offsets
> > +  */
> > +static void bdw_update_pm_irq(struct drm_i915_private *dev_priv,
> > +                             uint32_t interrupt_mask,
> > +                             uint32_t enabled_irq_mask)
> > +{
> > +       uint32_t new_val;
> > +
> > +       assert_spin_locked(&dev_priv->irq_lock);
> > +
> > +       if (dev_priv->pc8.irqs_disabled) {
> > +               WARN(1, "IRQs disabled\n");
> > +               dev_priv->pc8.regsave.gen6_pmimr &= ~interrupt_mask;
> > +               dev_priv->pc8.regsave.gen6_pmimr |= (~enabled_irq_mask &
> > +                                                    interrupt_mask);
> > +               return;
> > +       }
> > +
> > +       new_val = dev_priv->pm_irq_mask;
> > +       new_val &= ~interrupt_mask;
> > +       new_val |= (~enabled_irq_mask & interrupt_mask);
> > +
> > +       if (new_val != dev_priv->pm_irq_mask) {
> > +               dev_priv->pm_irq_mask = new_val;
> > +               I915_WRITE(GEN8_GT_IMR(2), I915_READ(GEN8_GT_IMR(2)) |
> > +                                          dev_priv->pm_irq_mask);
> > +               POSTING_READ(GEN8_GT_IMR(2));
> > +       }
> > +}
> > +
> > +void bdw_enable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask)
> > +{
> > +       bdw_update_pm_irq(dev_priv, mask, mask);
> > +}
> > +
> > +void bdw_disable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask)
> > +{
> > +       bdw_update_pm_irq(dev_priv, mask, 0);
> > +}
> > +
> > +
> >  static bool cpt_can_enable_serr_int(struct drm_device *dev)
> >  {
> >         struct drm_i915_private *dev_priv = dev->dev_private;
> > @@ -997,11 +1044,15 @@ static void gen6_pm_rps_work(struct work_struct *work)
> >         pm_iir = dev_priv->rps.pm_iir;
> >         dev_priv->rps.pm_iir = 0;
> >         /* Make sure not to corrupt PMIMR state used by ringbuffer code */
> > -       snb_enable_pm_irq(dev_priv, GEN6_PM_RPS_EVENTS);
> > +       if (IS_BROADWELL(dev_priv->dev))
> > +               bdw_enable_pm_irq(dev_priv, GEN6_PM_RPS_EVENTS);
> > +       else {
> > +               /* Make sure we didn't queue anything we're not going to process. */
> > +               snb_enable_pm_irq(dev_priv, GEN6_PM_RPS_EVENTS);
> 
> inverted lines since comment sounds to be related to above line.
> 

It's not inverted in it's current state, but it isn't quite clear
either.  I've moved the comment about corruption up to the snb interrupt
write code. It no longer makes sense here at all.

@@ -175,6 +175,7 @@ static void snb_update_pm_irq(struct drm_i915_private *dev_priv,
                return;
        }
 
+       /* Make sure not to corrupt PMIMR state used by ringbuffer code */
        new_val = dev_priv->pm_irq_mask;
        new_val &= ~interrupt_mask;
        new_val |= (~enabled_irq_mask & interrupt_mask);
@@ -1153,17 +1154,16 @@ static void gen6_pm_rps_work(struct work_struct *work)
        spin_lock_irq(&dev_priv->irq_lock);
        pm_iir = dev_priv->rps.pm_iir;
        dev_priv->rps.pm_iir = 0;
-       /* Make sure not to corrupt PMIMR state used by ringbuffer code */
        if (IS_BROADWELL(dev_priv->dev))
                bdw_enable_pm_irq(dev_priv, GEN6_PM_RPS_EVENTS);
        else {
-               /* Make sure we didn't queue anything we're not going to process. */
                snb_enable_pm_irq(dev_priv, GEN6_PM_RPS_EVENTS);
+               /* Make sure we didn't queue anything we're not going to
+                * process. */
                WARN_ON(pm_iir & ~GEN6_PM_RPS_EVENTS);
        }


> > +               WARN_ON(pm_iir & ~GEN6_PM_RPS_EVENTS);
> > +       }
> >         spin_unlock_irq(&dev_priv->irq_lock);
> >
> > -       /* Make sure we didn't queue anything we're not going to process. */
> > -       WARN_ON(pm_iir & ~GEN6_PM_RPS_EVENTS);
> >
> >         if ((pm_iir & GEN6_PM_RPS_EVENTS) == 0)
> >                 return;
> > @@ -1192,6 +1243,19 @@ static void snb_gt_irq_handler(struct drm_device *dev,
> >                 ivybridge_parity_error_irq_handler(dev, gt_iir);
> >  }
> >
> > +static void gen8_rps_irq_handler(struct drm_i915_private *dev_priv, u32 pm_iir)
> > +{
> > +       if ((pm_iir & GEN6_PM_RPS_EVENTS) == 0)
> > +               return;
> > +
> > +       spin_lock(&dev_priv->irq_lock);
> > +       dev_priv->rps.pm_iir |= pm_iir & GEN6_PM_RPS_EVENTS;
> > +       bdw_disable_pm_irq(dev_priv, pm_iir & GEN6_PM_RPS_EVENTS);
> > +       spin_unlock(&dev_priv->irq_lock);
> > +
> > +       queue_work(dev_priv->wq, &dev_priv->rps.work);
> 
> sorry if this is a stupid question, but don't we need the vebox part here?
> 

The reason we do not need a vebox part here is because on gen8 they
split up the PM interrupts and GT interrupts properly. I've only even
kept the separate function to keep with the gen6 style - there isn't
really any risk of complexity like there was pre-gen8.

Even the ring interrupt masks are much easier to manage on gen8, so much
of that code can probably be simplified (I think I left a few comments
or commit msgs stating as much, but I can't recall). At this point, I
just want to get the code running, and RPS working, and then move on.

> > +}
> > +
> >  static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
> >                                        struct drm_i915_private *dev_priv,
> >                                        u32 master_ctl)
> > @@ -1227,6 +1291,16 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
> >                         DRM_ERROR("The master control interrupt lied (GT1)!\n");
> >         }
> >
> > +       if (master_ctl & GEN8_GT_PM_IRQ) {
> > +               tmp = I915_READ(GEN8_GT_IIR(2));
> > +               if (tmp & GEN6_PM_RPS_EVENTS) {
> > +                       ret = IRQ_HANDLED;
> > +                       gen8_rps_irq_handler(dev_priv, tmp);
> > +                       I915_WRITE(GEN8_GT_IIR(1), tmp & GEN6_PM_RPS_EVENTS);
> > +               } else
> > +                       DRM_ERROR("The master control interrupt lied (PM)!\n");
> > +       }
> > +
> >         if (master_ctl & GEN8_GT_VECS_IRQ) {
> >                 tmp = I915_READ(GEN8_GT_IIR(3));
> >                 if (tmp) {
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index d77720e..f9e582e 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -4024,6 +4024,7 @@
> >  #define  GEN8_DE_PIPE_A_IRQ            (1<<16)
> >  #define  GEN8_DE_PIPE_IRQ(pipe)                (1<<(16+pipe))
> >  #define  GEN8_GT_VECS_IRQ              (1<<6)
> > +#define  GEN8_GT_PM_IRQ                        (1<<4)
> >  #define  GEN8_GT_VCS2_IRQ              (1<<3)
> >  #define  GEN8_GT_VCS1_IRQ              (1<<2)
> >  #define  GEN8_GT_BCS_IRQ               (1<<1)
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > index 44067bc..7b49779 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -608,6 +608,8 @@ void ilk_enable_gt_irq(struct drm_i915_private *dev_priv, uint32_t mask);
> >  void ilk_disable_gt_irq(struct drm_i915_private *dev_priv, uint32_t mask);
> >  void snb_enable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
> >  void snb_disable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
> > +void bdw_enable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
> > +void bdw_disable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
> >  void hsw_pc8_disable_interrupts(struct drm_device *dev);
> >  void hsw_pc8_restore_interrupts(struct drm_device *dev);
> >
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index deaaaf2..a5c9142 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -3091,6 +3091,25 @@ void valleyview_set_rps(struct drm_device *dev, u8 val)
> >         trace_intel_gpu_freq_change(vlv_gpu_freq(dev_priv, val));
> >  }
> >
> > +static void gen8_disable_rps_interrupts(struct drm_device *dev)
> > +{
> > +       struct drm_i915_private *dev_priv = dev->dev_private;
> > +
> > +       I915_WRITE(GEN6_PMINTRMSK, 0xffffffff);
> > +       I915_WRITE(GEN8_GT_IER(2), I915_READ(GEN8_GT_IER(2)) &
> > +                                  ~GEN6_PM_RPS_EVENTS);
> > +       /* Complete PM interrupt masking here doesn't race with the rps work
> > +        * item again unmasking PM interrupts because that is using a different
> > +        * register (PMIMR) to mask PM interrupts. The only risk is in leaving
> > +        * stale bits in PMIIR and PMIMR which gen6_enable_rps will clean up. */
> > +
> > +       spin_lock_irq(&dev_priv->irq_lock);
> > +       dev_priv->rps.pm_iir = 0;
> > +       spin_unlock_irq(&dev_priv->irq_lock);
> > +
> > +       I915_WRITE(GEN8_GT_IIR(2), GEN6_PM_RPS_EVENTS);
> > +}
> > +
> >  static void gen6_disable_rps_interrupts(struct drm_device *dev)
> >  {
> >         struct drm_i915_private *dev_priv = dev->dev_private;
> > @@ -3116,7 +3135,10 @@ static void gen6_disable_rps(struct drm_device *dev)
> >         I915_WRITE(GEN6_RC_CONTROL, 0);
> >         I915_WRITE(GEN6_RPNSWREQ, 1 << 31);
> >
> > -       gen6_disable_rps_interrupts(dev);
> > +       if (IS_BROADWELL(dev))
> > +               gen8_disable_rps_interrupts(dev);
> > +       else
> > +               gen6_disable_rps_interrupts(dev);
> >  }
> >
> >  static void valleyview_disable_rps(struct drm_device *dev)
> > @@ -3161,6 +3183,19 @@ int intel_enable_rc6(const struct drm_device *dev)
> >                 return INTEL_RC6_ENABLE;
> >  }
> >
> > +static void gen8_enable_rps_interrupts(struct drm_device *dev)
> > +{
> > +       struct drm_i915_private *dev_priv = dev->dev_private;
> > +
> > +       spin_lock_irq(&dev_priv->irq_lock);
> > +       WARN_ON(dev_priv->rps.pm_iir);
> > +       bdw_enable_pm_irq(dev_priv, GEN6_PM_RPS_EVENTS);
> > +       I915_WRITE(GEN8_GT_IIR(2), GEN6_PM_RPS_EVENTS);
> > +       spin_unlock_irq(&dev_priv->irq_lock);
> > +
> > +       I915_WRITE(GEN6_PMINTRMSK, ~GEN6_PM_RPS_EVENTS);
> > +}
> > +
> >  static void gen6_enable_rps_interrupts(struct drm_device *dev)
> >  {
> >         struct drm_i915_private *dev_priv = dev->dev_private;
> > @@ -3263,7 +3298,7 @@ static void gen8_enable_rps(struct drm_device *dev)
> >
> >         gen6_set_rps(dev, (I915_READ(GEN6_GT_PERF_STATUS) & 0xff00) >> 8);
> >
> > -       gen6_enable_rps_interrupts(dev);
> > +       gen8_enable_rps_interrupts(dev);
> >
> >         gen6_gt_force_wake_put(dev_priv, FORCEWAKE_ALL);
> >  }
> > --
> > 1.8.5.3
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> with those explained or fixed feel free to use:
> 
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
> 

Since I reworked a lot of the code, I was planning to drop your r-b on
some earlier patches too. I'll leave this one unreviewed and you can
tell me how satisfied you are after the repost.

> -- 
> Rodrigo Vivi
> Blog: http://blog.vivi.eng.br

-- 
Ben Widawsky, Intel Open Source Technology Center
