Re: [PATCH 1/3] drm/i915: Hide the atomic_read(reset_counter) behind a helper

From: Daniel Vetter <daniel@ffwll.ch>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: daniel.vetter@ffwll.ch, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/3] drm/i915: Hide the atomic_read(reset_counter) behind a helper
Date: Thu, 3 Dec 2015 09:57:01 +0100	[thread overview]
Message-ID: <20151203085701.GJ10243@phenom.ffwll.local> (raw)
In-Reply-To: <1448967935-21760-1-git-send-email-chris@chris-wilson.co.uk>

On Tue, Dec 01, 2015 at 11:05:33AM +0000, Chris Wilson wrote:
> This is just a little bit of syntatic sugar to hide the atomic_reads()
> throughout the code to retrieve the current reset_counter. It also
> provides the other utility functions to check the reset state on the
> already read reset_counter, so that we can read it once and do multiple
> tests rather than risk the value changing between tests.

This patch also changes the meaning of reset_in_progress to not include
WEDGED afaict. I agree with that change, but it needs to be mentioned in
the commit message.

Also with that change there's some cleanup potential since a bunch of
callers that explicitly checked for reset_in_progress &&
!terminally_wedged now can drop the 2nd part of the condition. That
simplification is why I've done this change in my patch.
-Daniel

> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c     |  2 +-
>  drivers/gpu/drm/i915/i915_drv.h         | 32 ++++++++++++++++++++++++++++----
>  drivers/gpu/drm/i915/i915_gem.c         | 12 ++++++------
>  drivers/gpu/drm/i915/intel_display.c    | 16 ++++++++++------
>  drivers/gpu/drm/i915/intel_ringbuffer.c |  2 +-
>  5 files changed, 46 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index bfd57fb597dc..864b3ae9419c 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4656,7 +4656,7 @@ i915_wedged_get(void *data, u64 *val)
>  	struct drm_device *dev = data;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  
> -	*val = atomic_read(&dev_priv->gpu_error.reset_counter);
> +	*val = i915_reset_counter(&dev_priv->gpu_error);
>  
>  	return 0;
>  }
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index d07041c1729d..2a4cfa06c28d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2979,20 +2979,44 @@ void i915_gem_retire_requests_ring(struct intel_engine_cs *ring);
>  int __must_check i915_gem_check_wedge(struct i915_gpu_error *error,
>  				      bool interruptible);
>  
> +static inline u32 i915_reset_counter(struct i915_gpu_error *error)
> +{
> +	return atomic_read(&error->reset_counter);
> +}
> +
> +static inline bool __i915_reset_in_progress(u32 reset)
> +{
> +	return unlikely(reset & I915_RESET_IN_PROGRESS_FLAG);
> +}
> +
> +static inline bool __i915_reset_in_progress_or_wedged(u32 reset)
> +{
> +	return unlikely(reset & (I915_RESET_IN_PROGRESS_FLAG | I915_WEDGED));
> +}
> +
> +static inline bool __i915_terminally_wedged(u32 reset)
> +{
> +	return unlikely(reset & I915_WEDGED);
> +}
> +
>  static inline bool i915_reset_in_progress(struct i915_gpu_error *error)
>  {
> -	return unlikely(atomic_read(&error->reset_counter)
> -			& (I915_RESET_IN_PROGRESS_FLAG | I915_WEDGED));
> +	return __i915_reset_in_progress(i915_reset_counter(error));
> +}
> +
> +static inline bool i915_reset_in_progress_or_wedged(struct i915_gpu_error *error)
> +{
> +	return __i915_reset_in_progress_or_wedged(i915_reset_counter(error));
>  }
>  
>  static inline bool i915_terminally_wedged(struct i915_gpu_error *error)
>  {
> -	return atomic_read(&error->reset_counter) & I915_WEDGED;
> +	return __i915_terminally_wedged(i915_reset_counter(error));
>  }
>  
>  static inline u32 i915_reset_count(struct i915_gpu_error *error)
>  {
> -	return ((atomic_read(&error->reset_counter) & ~I915_WEDGED) + 1) / 2;
> +	return ((i915_reset_counter(error) & ~I915_WEDGED) + 1) / 2;
>  }
>  
>  static inline bool i915_stop_ring_allow_ban(struct drm_i915_private *dev_priv)
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index cccfe5bfe5bf..bff245de8ade 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1297,7 +1297,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
>  
>  		/* We need to check whether any gpu reset happened in between
>  		 * the caller grabbing the seqno and now ... */
> -		if (reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter)) {
> +		if (reset_counter != i915_reset_counter(&dev_priv->gpu_error)) {
>  			/* ... but upgrade the -EAGAIN to an -EIO if the gpu
>  			 * is truely gone. */
>  			ret = i915_gem_check_wedge(&dev_priv->gpu_error, interruptible);
> @@ -1475,7 +1475,7 @@ i915_wait_request(struct drm_i915_gem_request *req)
>  		return ret;
>  
>  	ret = __i915_wait_request(req,
> -				  atomic_read(&dev_priv->gpu_error.reset_counter),
> +				  i915_reset_counter(&dev_priv->gpu_error),
>  				  interruptible, NULL, NULL);
>  	if (ret)
>  		return ret;
> @@ -1564,7 +1564,7 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
>  	if (ret)
>  		return ret;
>  
> -	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
> +	reset_counter = i915_reset_counter(&dev_priv->gpu_error);
>  
>  	if (readonly) {
>  		struct drm_i915_gem_request *req;
> @@ -3110,7 +3110,7 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
>  	}
>  
>  	drm_gem_object_unreference(&obj->base);
> -	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
> +	reset_counter = i915_reset_counter(&dev_priv->gpu_error);
>  
>  	for (i = 0; i < I915_NUM_RINGS; i++) {
>  		if (obj->last_read_req[i] == NULL)
> @@ -3155,7 +3155,7 @@ __i915_gem_object_sync(struct drm_i915_gem_object *obj,
>  	if (!i915_semaphore_is_enabled(obj->base.dev)) {
>  		struct drm_i915_private *i915 = to_i915(obj->base.dev);
>  		ret = __i915_wait_request(from_req,
> -					  atomic_read(&i915->gpu_error.reset_counter),
> +					  i915_reset_counter(&i915->gpu_error),
>  					  i915->mm.interruptible,
>  					  NULL,
>  					  &i915->rps.semaphores);
> @@ -4109,7 +4109,7 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
>  
>  		target = request;
>  	}
> -	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
> +	reset_counter = i915_reset_counter(&dev_priv->gpu_error);
>  	if (target)
>  		i915_gem_request_reference(target);
>  	spin_unlock(&file_priv->mm.lock);
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 4ae490dfe2c4..511ead08ccd8 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3287,10 +3287,12 @@ static bool intel_crtc_has_pending_flip(struct drm_crtc *crtc)
>  	struct drm_device *dev = crtc->dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> +	unsigned reset_counter;
>  	bool pending;
>  
> -	if (i915_reset_in_progress(&dev_priv->gpu_error) ||
> -	    intel_crtc->reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter))
> +	reset_counter = i915_reset_counter(&dev_priv->gpu_error);
> +	if (intel_crtc->reset_counter != reset_counter ||
> +	    __i915_reset_in_progress(reset_counter))
>  		return false;
>  
>  	spin_lock_irq(&dev->event_lock);
> @@ -10865,9 +10867,11 @@ static bool page_flip_finished(struct intel_crtc *crtc)
>  {
>  	struct drm_device *dev = crtc->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> +	unsigned reset_counter;
>  
> -	if (i915_reset_in_progress(&dev_priv->gpu_error) ||
> -	    crtc->reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter))
> +	reset_counter = i915_reset_counter(&dev_priv->gpu_error);
> +	if (crtc->reset_counter != reset_counter ||
> +	    __i915_reset_in_progress(reset_counter))
>  		return true;
>  
>  	/*
> @@ -11511,7 +11515,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
>  		goto cleanup;
>  
>  	atomic_inc(&intel_crtc->unpin_work_count);
> -	intel_crtc->reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
> +	intel_crtc->reset_counter = i915_reset_counter(&dev_priv->gpu_error);
>  
>  	if (INTEL_INFO(dev)->gen >= 5 || IS_G4X(dev))
>  		work->flip_count = I915_READ(PIPE_FLIPCOUNT_G4X(pipe)) + 1;
> @@ -13303,7 +13307,7 @@ static int intel_atomic_prepare_commit(struct drm_device *dev,
>  	if (!ret && !async && !i915_reset_in_progress(&dev_priv->gpu_error)) {
>  		u32 reset_counter;
>  
> -		reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
> +		reset_counter = i915_reset_counter(&dev_priv->gpu_error);
>  		mutex_unlock(&dev->struct_mutex);
>  
>  		for_each_plane_in_state(state, plane, plane_state, i) {
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 57d78f264b53..8970267d27bb 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -2286,7 +2286,7 @@ int intel_ring_idle(struct intel_engine_cs *ring)
>  
>  	/* Make sure we do not trigger any retires */
>  	return __i915_wait_request(req,
> -				   atomic_read(&to_i915(ring->dev)->gpu_error.reset_counter),
> +				   i915_reset_counter(&to_i915(ring->dev)->gpu_error),
>  				   to_i915(ring->dev)->mm.interruptible,
>  				   NULL, NULL);
>  }
> -- 
> 2.6.2
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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