On Thu, May 22, 2014 at 05:56:35PM +0200, Daniel Vetter wrote:
> Currently we do a full re-init of all interrupts after a gpu hang.
> Which is pretty bad since we don't restore the interrupts we've
> enabled at runtime correctly. Even with that addressed it's rather
> horribly race.
>
> But on g4x and later we only reset the gt and not the entire gpu.
> Which means we only need to reset the GT interrupt bits. Which has the
> nice benefit that vblank waits, pipe CRC interrupts and everything
> else display related just keeps on working.
>
> The downside is that gt interrupt handling (i.e. ring->get/put_irq) is
> still racy. But as long as the gpu hang reliably wakes all waters and
> we have a short time where the refcount drops to 0 we'll recover. So
> not that bad really.
A quick test on IVB tells me that GTIMR and GEN6_PMIMR survive the full
gt reset. But the ring IMRs do get clobbered. So could we just skip the
entire irq reset here?
>
> Testcase: igt/kms_flip/vblank-vs-hang
> Testcase: igt/kms_pipe_crc_basic/hang-*
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 17 +++++++++--------
> drivers/gpu/drm/i915/i915_drv.h | 1 +
> drivers/gpu/drm/i915/i915_irq.c | 35 +++++++++++++++++++++++++++--------
> 3 files changed, 37 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index c83c83b74bf4..69a75bb7ad83 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -811,17 +811,18 @@ int i915_reset(struct drm_device *dev)
> }
>
> /*
> - * FIXME: This is horribly race against concurrent pageflip and
> - * vblank wait ioctls since they can observe dev->irqs_disabled
> - * being false when they shouldn't be able to.
> + * FIXME: This races pretty badly against concurrent holders of
> + * ring interrupts. This is possible since we've started to drop
> + * dev->struct_mutex in select places when waiting for the gpu.
> */
> - drm_irq_uninstall(dev);
> - drm_irq_install(dev, dev->pdev->irq);
> + intel_gt_irq_reinit(dev);
>
> - /* rps/rc6 re-init is necessary to restore state lost after the
> - * reset and the re-install of drm irq. Skip for ironlake per
> + /*
> + * rps/rc6 re-init is necessary to restore state lost after the
> + * reset and the re-install of gt irqs. Skip for ironlake per
> * previous concerns that it doesn't respond well to some forms
> - * of re-init after reset. */
> + * of re-init after reset.
> + */
> if (INTEL_INFO(dev)->gen > 5)
> intel_reset_gt_powersave(dev);
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 459b02ad1ef3..61792c4050e7 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2078,6 +2078,7 @@ void gen6_set_pm_mask(struct drm_i915_private *dev_priv, u32 pm_iir,
> int new_delay);
> extern void intel_irq_init(struct drm_device *dev);
> extern void intel_hpd_init(struct drm_device *dev);
> +extern void intel_gt_irq_reinit(struct drm_device *dev);
>
> extern void intel_uncore_sanitize(struct drm_device *dev);
> extern void intel_uncore_early_sanitize(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 3cd659b47dd2..6dba645a81fa 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -3140,6 +3140,14 @@ static void valleyview_irq_preinstall(struct drm_device *dev)
> POSTING_READ(VLV_IER);
> }
>
> +static void gen8_gt_irq_reset(struct drm_i915_private *dev_priv)
> +{
> + GEN8_IRQ_RESET_NDX(GT, 0);
> + GEN8_IRQ_RESET_NDX(GT, 1);
> + GEN8_IRQ_RESET_NDX(GT, 2);
> + GEN8_IRQ_RESET_NDX(GT, 3);
> +}
> +
> static void gen8_irq_reset(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -3148,10 +3156,7 @@ static void gen8_irq_reset(struct drm_device *dev)
> I915_WRITE(GEN8_MASTER_IRQ, 0);
> POSTING_READ(GEN8_MASTER_IRQ);
>
> - GEN8_IRQ_RESET_NDX(GT, 0);
> - GEN8_IRQ_RESET_NDX(GT, 1);
> - GEN8_IRQ_RESET_NDX(GT, 2);
> - GEN8_IRQ_RESET_NDX(GT, 3);
> + gen8_gt_irq_reset(dev_priv);
>
> for_each_pipe(pipe)
> GEN8_IRQ_RESET_NDX(DE_PIPE, pipe);
> @@ -3171,10 +3176,7 @@ static void cherryview_irq_preinstall(struct drm_device *dev)
> I915_WRITE(GEN8_MASTER_IRQ, 0);
> POSTING_READ(GEN8_MASTER_IRQ);
>
> - GEN8_IRQ_RESET_NDX(GT, 0);
> - GEN8_IRQ_RESET_NDX(GT, 1);
> - GEN8_IRQ_RESET_NDX(GT, 2);
> - GEN8_IRQ_RESET_NDX(GT, 3);
> + gen8_gt_irq_reset(dev_priv);
>
> GEN5_IRQ_RESET(GEN8_PCU_);
>
> @@ -4436,6 +4438,23 @@ void intel_hpd_init(struct drm_device *dev)
> spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
> }
>
> +void intel_gt_irq_reinit(struct drm_device *dev)
> +{
> + struct drm_i915_private *dev_priv = dev->dev_private;
> +
> + spin_lock_irq(&dev_priv->irq_lock);
> + if (INTEL_INFO(dev)->gen >= 8) {
> + gen8_gt_irq_reset(dev_priv);
> + gen8_gt_irq_postinstall(dev_priv);
> + } else if (INTEL_INFO(dev)->gen >= 5) {
> + gen5_gt_irq_reset(dev);
> + gen5_gt_irq_postinstall(dev);
> + } else {
> + WARN_ON(!IS_G4X(dev));
> + }
> + spin_unlock_irq(&dev_priv->irq_lock);
> +}
> +
> /* Disable interrupts so we can allow runtime PM. */
> void intel_runtime_pm_disable_interrupts(struct drm_device *dev)
> {
> --
> 1.8.4.rc3
>
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--
Ville Syrjälä
Intel OTC
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