Re: [PATCH 08/20] drm/i915: check if IIR is still zero at postinstall on Gen5+

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Mar 18, 2014 at 11:20:09AM -0700, Ben Widawsky wrote:
> On Fri, Mar 07, 2014 at 08:10:24PM -0300, Paulo Zanoni wrote:
> > From: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > 
> > Instead of trying to clear it again. It should already be masked and
> > disabled and zeroed at preinstall/uninstall.
> > 
> > Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_irq.c | 32 +++++++++++++++-----------------
> >  1 file changed, 15 insertions(+), 17 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > index 6d4daf2..4d0a8b1 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -103,12 +103,24 @@ static const u32 hpd_status_i915[] = { /* i915 and valleyview are the same */
> >  	I915_WRITE(type##IIR, 0xffffffff); \
> >  } while (0)
> >  
> > +/*
> > + * We should clear IMR at preinstall/uninstall, and just check at postinstall.
> > + */
> > +#define GEN5_ASSERT_IIR_IS_ZERO(reg) do { \
> > +	u32 val = I915_READ(reg); \
> > +	if (val) \
> > +		DRM_ERROR("Interrupt register 0x%x is not zero: 0x%08x\n", \
> > +			  (reg), val); \
> > +} while (0)
> > +
> >  #define GEN8_IRQ_INIT_NDX(type, which, imr_val, ier_val) do { \
> > +	GEN5_ASSERT_IIR_IS_ZERO(GEN8_##type##_IIR(which)); \
> >  	I915_WRITE(GEN8_##type##_IMR(which), (imr_val)); \
> >  	I915_WRITE(GEN8_##type##_IER(which), (ier_val)); \
> >  } while (0)
> >  
> >  #define GEN5_IRQ_INIT(type, imr_val, ier_val) do { \
> > +	GEN5_ASSERT_IIR_IS_ZERO(type##IIR); \
> >  	I915_WRITE(type##IMR, (imr_val)); \
> >  	I915_WRITE(type##IER, (ier_val)); \
> >  } while (0)
> 
> Okay, this is replacing a POSTED_WRITE, with a (slower) POSTING_READ
> which gives an error that we can do nothing about other than clear it
> anyway.
> 
> I'd be in favor of dropping this patch.

The point of the assert is to make sure that the new IIR clearing logic
with blocking everything+clearing in the preinstall hook actually does
what it's supposed to do.

Since the point of this exercise is to reuse this code for runtime
suspend/resume where races are much easier to hit I think this is a good
self-check of the code.
-Daniel

> 
> > @@ -2940,7 +2952,7 @@ static void ibx_irq_postinstall(struct drm_device *dev)
> >  		I915_WRITE(SERR_INT, I915_READ(SERR_INT));
> >  	}
> >  
> > -	I915_WRITE(SDEIIR, I915_READ(SDEIIR));
> > +	GEN5_ASSERT_IIR_IS_ZERO(SDEIIR);
> >  	I915_WRITE(SDEIMR, ~mask);
> >  }
> >  
> > @@ -2966,7 +2978,6 @@ static void gen5_gt_irq_postinstall(struct drm_device *dev)
> >  		gt_irqs |= GT_BLT_USER_INTERRUPT | GT_BSD_USER_INTERRUPT;
> >  	}
> >  
> > -	I915_WRITE(GTIIR, I915_READ(GTIIR));
> >  	GEN5_IRQ_INIT(GT, dev_priv->gt_irq_mask, gt_irqs);
> >  
> >  	if (INTEL_INFO(dev)->gen >= 6) {
> > @@ -2976,7 +2987,6 @@ static void gen5_gt_irq_postinstall(struct drm_device *dev)
> >  			pm_irqs |= PM_VEBOX_USER_INTERRUPT;
> >  
> >  		dev_priv->pm_irq_mask = 0xffffffff;
> > -		I915_WRITE(GEN6_PMIIR, I915_READ(GEN6_PMIIR));
> >  		GEN5_IRQ_INIT(GEN6_PM, dev_priv->pm_irq_mask, pm_irqs);
> >  	}
> >  	POSTING_READ(GTIER);
> > @@ -3010,8 +3020,6 @@ static int ironlake_irq_postinstall(struct drm_device *dev)
> >  
> >  	dev_priv->irq_mask = ~display_mask;
> >  
> > -	/* should always can generate irq */
> > -	I915_WRITE(DEIIR, I915_READ(DEIIR));
> >  	GEN5_IRQ_INIT(DE, dev_priv->irq_mask, display_mask | extra_mask);
> >  
> >  	gen5_gt_irq_postinstall(dev);
> > @@ -3172,13 +3180,8 @@ static void gen8_gt_irq_postinstall(struct drm_i915_private *dev_priv)
> >  		GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT
> >  		};
> >  
> > -	for (i = 0; i < ARRAY_SIZE(gt_interrupts); i++) {
> > -		u32 tmp = I915_READ(GEN8_GT_IIR(i));
> > -		if (tmp)
> > -			DRM_ERROR("Interrupt (%d) should have been masked in pre-install 0x%08x\n",
> > -				  i, tmp);
> > +	for (i = 0; i < ARRAY_SIZE(gt_interrupts); i++)
> >  		GEN8_IRQ_INIT_NDX(GT, i, ~gt_interrupts[i], gt_interrupts[i]);
> > -	}
> >  	POSTING_READ(GEN8_GT_IER(0));
> >  }
> >  
> > @@ -3195,14 +3198,9 @@ static void gen8_de_irq_postinstall(struct drm_i915_private *dev_priv)
> >  	dev_priv->de_irq_mask[PIPE_B] = ~de_pipe_masked;
> >  	dev_priv->de_irq_mask[PIPE_C] = ~de_pipe_masked;
> >  
> > -	for_each_pipe(pipe) {
> > -		u32 tmp = I915_READ(GEN8_DE_PIPE_IIR(pipe));
> > -		if (tmp)
> > -			DRM_ERROR("Interrupt (%d) should have been masked in pre-install 0x%08x\n",
> > -				  pipe, tmp);
> > +	for_each_pipe(pipe)
> >  		GEN8_IRQ_INIT_NDX(DE_PIPE, pipe, dev_priv->de_irq_mask[pipe],
> >  				  de_pipe_enables);
> > -	}
> >  	POSTING_READ(GEN8_DE_PIPE_ISR(0));
> >  
> >  	GEN5_IRQ_INIT(GEN8_DE_PORT_, ~GEN8_AUX_CHANNEL_A, GEN8_AUX_CHANNEL_A);
> > -- 
> > 1.8.5.3
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ben Widawsky, Intel Open Source Technology Center
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch