Re: [PATCH 07/27] drm/i915/icl: Interrupt handling

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

On Tue, 2018-01-09 at 21:23 -0200, Paulo Zanoni wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> 
> 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.
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>

<SNIP>

> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -415,6 +415,9 @@ void gen6_enable_rps_interrupts(struct drm_i915_private *dev_priv)
>  	if (READ_ONCE(rps->interrupts_enabled))
>  		return;
>  
> +	if (WARN_ON_ONCE(IS_GEN11(dev_priv)))
> +		return;
> +
>  	spin_lock_irq(&dev_priv->irq_lock);
>  	WARN_ON_ONCE(rps->pm_iir);
>  	WARN_ON_ONCE(I915_READ(gen6_pm_iir(dev_priv)) & dev_priv->pm_rps_events);
> @@ -431,6 +434,9 @@ void gen6_disable_rps_interrupts(struct drm_i915_private *dev_priv)
>  	if (!READ_ONCE(rps->interrupts_enabled))
>  		return;
>  
> +	if (WARN_ON_ONCE(IS_GEN11(dev_priv)))
> +		return;
> +

These should be GEM_BUG_ON at most and should be the first thing in
function.

>  	spin_lock_irq(&dev_priv->irq_lock);
>  	rps->interrupts_enabled = false;
>  
> @@ -2751,6 +2757,131 @@ static void __fini_wedge(struct wedge_me *w)
>  	     (W)->i915;							\
>  	     __fini_wedge((W)))
>  
> +static __always_inline void
> +gen11_cs_irq_handler(struct intel_engine_cs *engine, u32 iir)
> +{
> +	gen8_cs_irq_handler(engine, iir, 0);
> +}
> +
> +static irqreturn_t
> +gen11_gt_irq_handler(struct drm_i915_private *dev_priv, u32 master_ctl)

This function could use some readability :)

> +{
> +	irqreturn_t ret = IRQ_NONE;
> +	u16 irq[2][32];
> +	u32 dw, ident;
> +	unsigned long tmp;
> +	unsigned int bank, bit, engine;
> +	unsigned long wait_start, wait_end;
> +
> +	memset(irq, 0, sizeof(irq));
> +
> +	for (bank = 0; bank < 2; bank++) {
> +		if (master_ctl & GEN11_GT_DW_IRQ(bank)) {

Invert condition and use continue;

> +			dw = I915_READ_FW(GEN11_GT_INTR_DW(bank));
> +			if (!dw)
> +				DRM_ERROR("GT_INTR_DW%u blank!\n", bank);

Probably needs a more appropriate action, GEM_BUG_ON if we've never
seen this on HW.

> +			tmp = dw;
> +			for_each_set_bit(bit, &tmp, 32) {
> +				I915_WRITE_FW(GEN11_IIR_REG_SELECTOR(bank), 1 << bit);

BIT(bit)

+ newline here

> +				wait_start = local_clock() >> 10;
> +				/* NB: Specs do not specify how long to spin wait.
> +				 * Taking 100us as an educated guess */
> +				wait_end = wait_start + 100;
> +				do {
> +					ident = I915_READ_FW(GEN11_INTR_IDENTITY_REG(bank));
> +				} while (!(ident & GEN11_INTR_DATA_VALID) &&
> +					 !time_after((unsigned long)local_clock() >> 10, wait_end));

Uh oh, not a really nice thing to do in IRQ handler :( We should
probably look at some actual delay numbers and not do this.

> +
> +				if (!(ident & GEN11_INTR_DATA_VALID))
> +					DRM_ERROR("INTR_IDENTITY_REG%u:%u timed out!\n",
> +						  bank, bit);
> +
> +				irq[bank][bit] = ident & GEN11_INTR_ENGINE_MASK;
> +				if (!irq[bank][bit])
> +					DRM_ERROR("INTR_IDENTITY_REG%u:%u blank!\n",
> +						  bank, bit);

DRM_ERROR again seems like bit of an understatement for interrupt.

+ newline here

> +				I915_WRITE_FW(GEN11_INTR_IDENTITY_REG(bank), ident);
> +			}

+ newline here

> +			I915_WRITE_FW(GEN11_GT_INTR_DW(bank), dw);
> +		}
> +	}
> +
> +	if (irq[0][GEN11_RCS0]) {
> +		gen11_cs_irq_handler(dev_priv->engine[RCS],
> +				     irq[0][GEN11_RCS0]);
> +		ret = IRQ_HANDLED;
> +	}
> +
> +	if (irq[0][GEN11_BCS]) {
> +		gen11_cs_irq_handler(dev_priv->engine[BCS],
> +				     irq[0][GEN11_BCS]);
> +		ret = IRQ_HANDLED;
> +	}
> +
> +	for (engine = 0; engine < 4; engine++) {
> +		if (irq[1][GEN11_VCS(engine)]) {
> +			gen11_cs_irq_handler(dev_priv->engine[_VCS(engine)],
> +					     irq[1][GEN11_VCS(engine)]);
> +			ret = IRQ_HANDLED;
> +		}
> +	}
> +
> +	for (engine = 0; engine < 2; engine++) {
> +		if (irq[1][GEN11_VECS(engine)]) {
> +			gen11_cs_irq_handler(dev_priv->engine[_VECS(engine)],
> +					     irq[1][GEN11_VECS(engine)]);
> +			ret = IRQ_HANDLED;
> +		}
> +	}

Doesn't the above code look like a table to be iterated over?

<SNIP>

> +static void gen11_gt_irq_postinstall(struct drm_i915_private *dev_priv)
> +{
> +	const u32 irqs = GT_RENDER_USER_INTERRUPT | GT_CONTEXT_SWITCH_INTERRUPT;
> +
> +	BUILD_BUG_ON(irqs & 0xffff0000);

#define for the mask.

> +
> +	/* Enable RCS, BCS, VCS and VECS class interrupts. */
> +	I915_WRITE(GEN11_RENDER_COPY_INTR_ENABLE, irqs << 16 | irqs);
> +	I915_WRITE(GEN11_VCS_VECS_INTR_ENABLE,	  irqs << 16 | irqs);
> +
> +	/* Unmask irqs on RCS, BCS, VCS and VECS engines. */
> +	I915_WRITE(GEN11_RCS0_RSVD_INTR_MASK,	~(irqs << 16));
> +	I915_WRITE(GEN11_BCS_RSVD_INTR_MASK,	~(irqs << 16));
> +	I915_WRITE(GEN11_VCS0_VCS1_INTR_MASK,	~(irqs | irqs << 16));
> +	I915_WRITE(GEN11_VCS2_VCS3_INTR_MASK,	~(irqs | irqs << 16));
> +	I915_WRITE(GEN11_VECS0_VECS1_INTR_MASK,	~(irqs | irqs << 16));

We should also have an actual shift and mask #defines for these, now
it's all hardcoded here.

> +
> +	dev_priv->pm_imr = 0xffffffff; /* TODO */

Some code missing it seems.

> +}

<SNIP>

> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -7957,7 +7957,10 @@ void intel_sanitize_gt_powersave(struct drm_i915_private *dev_priv)
>  	dev_priv->gt_pm.rc6.enabled = true; /* force RC6 disabling */
>  	intel_disable_gt_powersave(dev_priv);
>  
> -	gen6_reset_rps_interrupts(dev_priv);
> +	if (INTEL_GEN(dev_priv) < 11)
> +		gen6_reset_rps_interrupts(dev_priv);
> +	else
> +		WARN_ON_ONCE(1);

Some code is obviously missing here.

>  }
>  
>  static inline void intel_disable_llc_pstate(struct drm_i915_private *i915)
> @@ -8070,6 +8073,8 @@ static void intel_enable_rps(struct drm_i915_private *dev_priv)
>  		cherryview_enable_rps(dev_priv);
>  	} else if (IS_VALLEYVIEW(dev_priv)) {
>  		valleyview_enable_rps(dev_priv);
> +	} else if (WARN_ON_ONCE(INTEL_GEN(dev_priv) >= 11)) {
> +		/* TODO */

Ditto.

If these are in a later patch, should be squashed here.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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