Re: [PATCH 1/3] drm/i915: Add PTE encoding function to the gtt/ppgtt vtables.

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 18 Apr 2013, Kenneth Graunke <kenneth@whitecape.org> wrote:
> Sandybridge/Ivybridge, Bay Trail, and Haswell all have slightly
> different page table entry formats.  Rather than polluting one function
> with generation checks, simply use a function pointer and set up the
> correct PTE encoding function at startup.
>
> Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> ---
>  drivers/gpu/drm/i915/i915_drv.h     |  6 ++++++
>  drivers/gpu/drm/i915/i915_gem_gtt.c | 22 +++++++++++++---------
>  2 files changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index bd2d7f1..8b58997 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -430,6 +430,9 @@ struct i915_gtt {
>  				   struct sg_table *st,
>  				   unsigned int pg_start,
>  				   enum i915_cache_level cache_level);
> +	uint32_t (*pte_encode)(struct drm_device *dev,
> +			       dma_addr_t addr,
> +			       enum i915_cache_level level);

To keep the gen6_gtt_pte_t typedef internal to i915_gem_gtt.c, or to
have the same return type in the function pointers and the functions. I
think I'd find the latter more aesthetically pleasing, but I'm not
insisting. Either way,

Reviewed-by: Jani Nikula <jani.nikula@intel.com>


>  };
>  #define gtt_total_entries(gtt) ((gtt).total >> PAGE_SHIFT)
>  
> @@ -451,6 +454,9 @@ struct i915_hw_ppgtt {
>  			       struct sg_table *st,
>  			       unsigned int pg_start,
>  			       enum i915_cache_level cache_level);
> +	uint32_t (*pte_encode)(struct drm_device *dev,
> +			       dma_addr_t addr,
> +			       enum i915_cache_level level);
>  	int (*enable)(struct drm_device *dev);
>  	void (*cleanup)(struct i915_hw_ppgtt *ppgtt);
>  };
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 50df194..9db65c1 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -154,9 +154,9 @@ static void gen6_ppgtt_clear_range(struct i915_hw_ppgtt *ppgtt,
>  	unsigned first_pte = first_entry % I915_PPGTT_PT_ENTRIES;
>  	unsigned last_pte, i;
>  
> -	scratch_pte = gen6_pte_encode(ppgtt->dev,
> -				      ppgtt->scratch_page_dma_addr,
> -				      I915_CACHE_LLC);
> +	scratch_pte = ppgtt->pte_encode(ppgtt->dev,
> +					ppgtt->scratch_page_dma_addr,
> +					I915_CACHE_LLC);
>  
>  	while (num_entries) {
>  		last_pte = first_pte + num_entries;
> @@ -191,8 +191,8 @@ static void gen6_ppgtt_insert_entries(struct i915_hw_ppgtt *ppgtt,
>  		dma_addr_t page_addr;
>  
>  		page_addr = sg_page_iter_dma_address(&sg_iter);
> -		pt_vaddr[act_pte] = gen6_pte_encode(ppgtt->dev, page_addr,
> -						    cache_level);
> +		pt_vaddr[act_pte] = ppgtt->pte_encode(ppgtt->dev, page_addr,
> +						      cache_level);
>  		if (++act_pte == I915_PPGTT_PT_ENTRIES) {
>  			kunmap_atomic(pt_vaddr);
>  			act_pt++;
> @@ -236,6 +236,7 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
>  	first_pd_entry_in_global_pt =
>  		gtt_total_entries(dev_priv->gtt) - I915_PPGTT_PD_ENTRIES;
>  
> +	ppgtt->pte_encode = gen6_pte_encode;
>  	ppgtt->num_pd_entries = I915_PPGTT_PD_ENTRIES;
>  	ppgtt->enable = gen6_ppgtt_enable;
>  	ppgtt->clear_range = gen6_ppgtt_clear_range;
> @@ -438,7 +439,8 @@ static void gen6_ggtt_insert_entries(struct drm_device *dev,
>  
>  	for_each_sg_page(st->sgl, &sg_iter, st->nents, 0) {
>  		addr = sg_page_iter_dma_address(&sg_iter);
> -		iowrite32(gen6_pte_encode(dev, addr, level), &gtt_entries[i]);
> +		iowrite32(dev_priv->gtt.pte_encode(dev, addr, level),
> +			  &gtt_entries[i]);
>  		i++;
>  	}
>  
> @@ -450,7 +452,7 @@ static void gen6_ggtt_insert_entries(struct drm_device *dev,
>  	 */
>  	if (i != 0)
>  		WARN_ON(readl(&gtt_entries[i-1])
> -			!= gen6_pte_encode(dev, addr, level));
> +			!= dev_priv->gtt.pte_encode(dev, addr, level));
>  
>  	/* This next bit makes the above posting read even more important. We
>  	 * want to flush the TLBs only after we're certain all the PTE updates
> @@ -475,8 +477,9 @@ static void gen6_ggtt_clear_range(struct drm_device *dev,
>  		 first_entry, num_entries, max_entries))
>  		num_entries = max_entries;
>  
> -	scratch_pte = gen6_pte_encode(dev, dev_priv->gtt.scratch_page_dma,
> -				      I915_CACHE_LLC);
> +	scratch_pte = dev_priv->gtt.pte_encode(dev,
> +					       dev_priv->gtt.scratch_page_dma,
> +					       I915_CACHE_LLC);
>  	for (i = 0; i < num_entries; i++)
>  		iowrite32(scratch_pte, &gtt_base[i]);
>  	readl(gtt_base);
> @@ -823,6 +826,7 @@ int i915_gem_gtt_init(struct drm_device *dev)
>  	} else {
>  		dev_priv->gtt.gtt_probe = gen6_gmch_probe;
>  		dev_priv->gtt.gtt_remove = gen6_gmch_remove;
> +		dev_priv->gtt.pte_encode = gen6_pte_encode;
>  	}
>  
>  	ret = dev_priv->gtt.gtt_probe(dev, &dev_priv->gtt.total,
> -- 
> 1.8.2.1
>
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