Re: [PATCH 1/8] drm/i915: Rebalance runtime pm vs forcewake

[Deepak S <deepak.s@linux.intel.com>]

On Monday 08 December 2014 11:57 PM, Mika Kuoppala wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
>
> Calling intel_runtime_pm_put() is illegal from a soft-irq context, so
> revert the crude hack
>
> commit aa0b3b5bb8768c1a6a6788869d9c7015eae7e80c
> Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Date:   Tue Apr 1 14:55:07 2014 -0300
>
>      drm/i915: don't schedule force_wake_timer at gen6_read
>
> and apply the single line corrective instead.
>
> References: https://bugs.freedesktop.org/show_bug.cgi?id=80913
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_drv.c     |  1 +
>   drivers/gpu/drm/i915/intel_uncore.c | 18 ++++++------------
>   2 files changed, 7 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 71be3c9..706b122 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1402,6 +1402,7 @@ static int intel_runtime_suspend(struct device *device)
>   	}
>   
>   	del_timer_sync(&dev_priv->gpu_error.hangcheck_timer);
> +	intel_uncore_forcewake_reset(dev, false);
>   	dev_priv->pm.suspended = true;
>   
>   	/*
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 46de8d7..38ac389 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -449,8 +449,6 @@ static void gen6_force_wake_timer(unsigned long arg)
>   	if (--dev_priv->uncore.forcewake_count == 0)
>   		dev_priv->uncore.funcs.force_wake_put(dev_priv, FORCEWAKE_ALL);
>   	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
> -
> -	intel_runtime_pm_put(dev_priv);
>   }
>   
>   void intel_uncore_forcewake_reset(struct drm_device *dev, bool restore)
> @@ -586,7 +584,6 @@ void gen6_gt_force_wake_get(struct drm_i915_private *dev_priv, int fw_engine)
>   void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv, int fw_engine)
>   {
>   	unsigned long irqflags;
> -	bool delayed = false;
>   
>   	if (!dev_priv->uncore.funcs.force_wake_put)
>   		return;
> @@ -603,21 +600,19 @@ void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv, int fw_engine)
>   		goto out;
>   	}
>   
> -
>   	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
>   	WARN_ON(!dev_priv->uncore.forcewake_count);
>   
>   	if (--dev_priv->uncore.forcewake_count == 0) {
>   		dev_priv->uncore.forcewake_count++;
> -		delayed = true;
>   		mod_timer_pinned(&dev_priv->uncore.force_wake_timer,
>   				 jiffies + 1);
>   	}
> +
>   	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>   
>   out:
> -	if (!delayed)
> -		intel_runtime_pm_put(dev_priv);
> +	intel_runtime_pm_put(dev_priv);
>   }
>   
>   void assert_force_wake_inactive(struct drm_i915_private *dev_priv)
> @@ -777,12 +772,11 @@ gen6_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
>   	    NEEDS_FORCE_WAKE((dev_priv), (reg))) { \
>   		dev_priv->uncore.funcs.force_wake_get(dev_priv, \
>   						      FORCEWAKE_ALL); \
> -		val = __raw_i915_read##x(dev_priv, reg); \
> -		dev_priv->uncore.funcs.force_wake_put(dev_priv, \
> -						      FORCEWAKE_ALL); \
> -	} else { \
> -		val = __raw_i915_read##x(dev_priv, reg); \
> +		dev_priv->uncore.forcewake_count++; \
> +		mod_timer_pinned(&dev_priv->uncore. , \
> +				 jiffies + 1); \

why timer, we can do a put after register read right?

Other changes looks fine to me
Reviewed-by: Deepak S <deepak.s@linux.intel.com>

>   	} \
> +	val = __raw_i915_read##x(dev_priv, reg); \
>   	hsw_unclaimed_reg_debug(dev_priv, reg, true, false); \
>   	REG_READ_FOOTER; \
>   }

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