Re: [PATCH 05/19] drm/i915/icl: Interrupt handling

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Quoting Mika Kuoppala (2018-02-14 14:12:13)
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> 
> v2: Rebase.
> 
> v3:
>   * Remove DPF, it has been removed from SKL+.
>   * Fix -internal rebase wrt. execlists interrupt handling.
> 
> v4: Rebase.
> 
> v5:
>   * Updated for POR changes. (Daniele Ceraolo Spurio)
>   * Merged with irq handling fixes by Daniele Ceraolo Spurio:
>       * Simplify the code by using gen8_cs_irq_handler.
>       * Fix interrupt handling for the upstream kernel.
> 
> v6:
>   * Remove early bringup debug messages (Tvrtko)
>   * Add NB about arbitrary spin wait timeout (Tvrtko)
> 
> v7 (from Paulo):
>   * Don't try to write RO bits to registers.
>   * Don't check for PCH types that don't exist. PCH interrupts are not
>     here yet.
> 
> v9:
>   * squashed in selector and shared register handling (Daniele)
>   * skip writing of irq if data is not valid (Daniele)
>   * use time_after32 (Chris)
>   * use I915_MAX_VCS and I915_MAX_VECS (Daniele)
>   * remove fake pm interrupt handling for later patch (Mika)
> 
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> Signed-off-by: Oscar Mateo <oscar.mateo@xxxxxxxxx>
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
> Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 212 ++++++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_pm.c |   7 +-
>  2 files changed, 218 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index b886bd459acc..9a2d12c8c44c 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -408,6 +408,37 @@ void gen6_reset_rps_interrupts(struct drm_i915_private *dev_priv)
>         spin_unlock_irq(&dev_priv->irq_lock);
>  }
>  
> +static int gen11_service_shared_iir(struct drm_i915_private *dev_priv,
> +                                   const unsigned int bank,
> +                                   const unsigned int bit)
> +{
> +       u64 wait_end;
> +       u32 ident;
> +       int irq;
> +
> +       I915_WRITE_FW(GEN11_IIR_REG_SELECTOR(bank), BIT(bit));
> +       /*
> +        * NB: Specs do not specify how long to spin wait.
> +        * Taking 100us as an educated guess
> +        */
> +       wait_end = (local_clock() >> 10) + 100;
> +       do {
> +               ident = I915_READ_FW(GEN11_INTR_IDENTITY_REG(bank));
> +       } while (!(ident & GEN11_INTR_DATA_VALID) &&
> +                !time_after32(local_clock() >> 10, wait_end));

Now you are just mixing types willy nilly :)

No need for wait_end to be 64b when we are looking at a 100 interval.

> +
> +       if (!(ident & GEN11_INTR_DATA_VALID)) {
> +               DRM_ERROR("INTR_IDENTITY_REG%u:%u timed out!\n", bank, bit);
> +               return -ETIMEDOUT;
> +       }
> +
> +       irq = ident & GEN11_INTR_ENGINE_MASK;
> +
> +       I915_WRITE_FW(GEN11_INTR_IDENTITY_REG(bank), ident);
> +
> +       return irq;

return ident & GEN11_INTR_ENGINE_MASK;

no need for irq, and why int return type?

Why is this gen11 specific helper so far away from the irq_handler?

> +static __always_inline void
> +gen11_cs_irq_handler(struct intel_engine_cs *engine, u32 iir)
> +{
> +       gen8_cs_irq_handler(engine, iir, 0);
> +}
> +
> +static void
> +gen11_gt_irq_handler(struct drm_i915_private *dev_priv, const u32 master_ctl)
> +{
> +       u16 irq[2][32];
> +       unsigned int bank, engine;
> +
> +       memset(irq, 0, sizeof(irq));
> +
> +       for (bank = 0; bank < 2; bank++) {
> +               unsigned long tmp;
> +               unsigned int bit;
> +               u32 dw;
> +               int ret;
> +
> +               if (!(master_ctl & GEN11_GT_DW_IRQ(bank)))
> +                       continue;
> +
> +               dw = I915_READ_FW(GEN11_GT_INTR_DW(bank));
> +               if (!dw)
> +                       DRM_ERROR("GT_INTR_DW%u blank!\n", bank);
> +
> +               tmp = dw;
> +               for_each_set_bit(bit, &tmp, 32) {

tmp is not required here.

> +                       ret = gen11_service_shared_iir(dev_priv, bank, bit);
> +                       if (unlikely(ret < 0))
> +                               continue;
> +
> +                       irq[bank][bit] = ret;
> +               }
> +
> +               I915_WRITE_FW(GEN11_GT_INTR_DW(bank), dw);

If we process the banks here, we won't need to memset 128 bytes and scan
untouched cachelines!

> +       }
> +
> +       if (irq[0][GEN11_RCS0])
> +               gen11_cs_irq_handler(dev_priv->engine[RCS],
> +                                    irq[0][GEN11_RCS0]);
> +
> +       if (irq[0][GEN11_BCS])
> +               gen11_cs_irq_handler(dev_priv->engine[BCS],
> +                                    irq[0][GEN11_BCS]);
> +
> +       for (engine = 0; engine < I915_MAX_VCS; engine++)
> +               if (irq[1][GEN11_VCS(engine)])
> +                       gen11_cs_irq_handler(dev_priv->engine[_VCS(engine)],
> +                                            irq[1][GEN11_VCS(engine)]);
> +
> +       for (engine = 0; engine < I915_MAX_VECS; engine++)
> +               if (irq[1][GEN11_VECS(engine)])
> +                       gen11_cs_irq_handler(dev_priv->engine[_VECS(engine)],
> +                                            irq[1][GEN11_VECS(engine)]);

Keep reminding yourself that this is the hottest function in the entire
i915.ko.

> +}
> +
> +static irqreturn_t gen11_irq_handler(int irq, void *arg)
> +{
> +       struct drm_device *dev = arg;
> +       struct drm_i915_private *dev_priv = dev->dev_private;

What?

> +       u32 master_ctl;
> +       u32 disp_ctl;

Why is this at top level scope?

> +       if (!intel_irqs_enabled(dev_priv))
> +               return IRQ_NONE;
> +
> +       master_ctl = I915_READ_FW(GEN11_GFX_MSTR_IRQ);
> +       master_ctl &= ~GEN11_MASTER_IRQ;
> +       if (!master_ctl)
> +               return IRQ_NONE;
> +
> +       /* Disable interrupts. */
> +       I915_WRITE_FW(GEN11_GFX_MSTR_IRQ, 0);
> +
> +       /* IRQs are synced during runtime_suspend, we don't require a wakeref */
> +       disable_rpm_wakeref_asserts(dev_priv);
> +
> +       /* Find, clear, then process each source of interrupt. */
> +       gen11_gt_irq_handler(dev_priv, master_ctl);
> +
> +       if (master_ctl & GEN11_DISPLAY_IRQ) {
> +               disp_ctl = I915_READ_FW(GEN11_DISPLAY_INT_CTL);
> +               gen8_de_irq_handler(dev_priv, disp_ctl);
> +       }
> +
> +       /* Acknowledge and enable interrupts. */
> +       I915_WRITE_FW(GEN11_GFX_MSTR_IRQ, GEN11_MASTER_IRQ | master_ctl);
> +       POSTING_READ_FW(GEN11_GFX_MSTR_IRQ);
> +
> +       enable_rpm_wakeref_asserts(dev_priv);

What happened to the onion? gen8 is broken as well, sure I sent patches
to fix that. The posting read is ott, and you don't need to disable the
asserts around the GT irq handler.
-Chris
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