Re: [PATCH 14/21] drm/i915/gtt: Make scratch page i915_page_dma compatible

[Michel Thierry <michel.thierry@intel.com>]

On 5/22/2015 6:05 PM, Mika Kuoppala wrote:
> Lay out scratch page structure in similar manner than other
> paging structures. This allows us to use the same tools for
> setup and teardown.
>
> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_gem_gtt.c | 89 ++++++++++++++++++++-----------------
>   drivers/gpu/drm/i915/i915_gem_gtt.h |  9 ++--
>   2 files changed, 54 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 4f9a000..43fa543 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -301,11 +301,12 @@ static gen6_pte_t iris_pte_encode(dma_addr_t addr,
>          return pte;
>   }
>
> -static int setup_page_dma(struct drm_device *dev, struct i915_page_dma *p)
> +static int __setup_page_dma(struct drm_device *dev,
> +                           struct i915_page_dma *p, gfp_t flags)
>   {
>          struct device *device = &dev->pdev->dev;
>
> -       p->page = alloc_page(GFP_KERNEL);
> +       p->page = alloc_page(flags);
>          if (!p->page)
>                  return -ENOMEM;
>
> @@ -320,6 +321,11 @@ static int setup_page_dma(struct drm_device *dev, struct i915_page_dma *p)
>          return 0;
>   }
>
> +static int setup_page_dma(struct drm_device *dev, struct i915_page_dma *p)
> +{
> +       return __setup_page_dma(dev, p, GFP_KERNEL);
> +}
> +
>   static void cleanup_page_dma(struct drm_device *dev, struct i915_page_dma *p)
>   {
>          if (WARN_ON(!p->page))
> @@ -388,7 +394,8 @@ static void gen8_initialize_pt(struct i915_address_space *vm,
>   {
>          gen8_pte_t scratch_pte;
>
> -       scratch_pte = gen8_pte_encode(vm->scratch.addr, I915_CACHE_LLC, true);
> +       scratch_pte = gen8_pte_encode(px_dma(vm->scratch_page),
> +                                     I915_CACHE_LLC, true);
>
>          fill_px(vm->dev, pt, scratch_pte);
>   }
> @@ -515,7 +522,7 @@ static void gen8_ppgtt_clear_range(struct i915_address_space *vm,
>          unsigned num_entries = length >> PAGE_SHIFT;
>          unsigned last_pte, i;
>
> -       scratch_pte = gen8_pte_encode(ppgtt->base.scratch.addr,
> +       scratch_pte = gen8_pte_encode(px_dma(ppgtt->base.scratch_page),
>                                        I915_CACHE_LLC, use_scratch);
>
>          while (num_entries) {
> @@ -1021,7 +1028,7 @@ static void gen6_dump_ppgtt(struct i915_hw_ppgtt *ppgtt, struct seq_file *m)
>          uint32_t  pte, pde, temp;
>          uint32_t start = ppgtt->base.start, length = ppgtt->base.total;
>
> -       scratch_pte = vm->pte_encode(vm->scratch.addr, I915_CACHE_LLC, true, 0);
> +       scratch_pte = vm->pte_encode(px_dma(vm->scratch_page), I915_CACHE_LLC, true, 0);
>
>          gen6_for_each_pde(unused, &ppgtt->pd, start, length, temp, pde) {
>                  u32 expected;
> @@ -1256,7 +1263,8 @@ static void gen6_ppgtt_clear_range(struct i915_address_space *vm,
>          unsigned first_pte = first_entry % GEN6_PTES;
>          unsigned last_pte, i;
>
> -       scratch_pte = vm->pte_encode(vm->scratch.addr, I915_CACHE_LLC, true, 0);
> +       scratch_pte = vm->pte_encode(px_dma(vm->scratch_page),
> +                                    I915_CACHE_LLC, true, 0);
>
>          while (num_entries) {
>                  last_pte = first_pte + num_entries;
> @@ -1314,9 +1322,10 @@ static void gen6_initialize_pt(struct i915_address_space *vm,
>   {
>          gen6_pte_t scratch_pte;
>
> -       WARN_ON(vm->scratch.addr == 0);
> +       WARN_ON(px_dma(vm->scratch_page) == 0);
>
> -       scratch_pte = vm->pte_encode(vm->scratch.addr, I915_CACHE_LLC, true, 0);
> +       scratch_pte = vm->pte_encode(px_dma(vm->scratch_page),
> +                                    I915_CACHE_LLC, true, 0);
>
>          fill32_px(vm->dev, pt, scratch_pte);
>   }
> @@ -1553,13 +1562,14 @@ static int __hw_ppgtt_init(struct drm_device *dev, struct i915_hw_ppgtt *ppgtt)
>          struct drm_i915_private *dev_priv = dev->dev_private;
>
>          ppgtt->base.dev = dev;
> -       ppgtt->base.scratch = dev_priv->gtt.base.scratch;
> +       ppgtt->base.scratch_page = dev_priv->gtt.base.scratch_page;
>
>          if (INTEL_INFO(dev)->gen < 8)
>                  return gen6_ppgtt_init(ppgtt);
>          else
>                  return gen8_ppgtt_init(ppgtt);
>   }
> +
>   int i915_ppgtt_init(struct drm_device *dev, struct i915_hw_ppgtt *ppgtt)
>   {
>          struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -1874,7 +1884,7 @@ static void gen8_ggtt_clear_range(struct i915_address_space *vm,
>                   first_entry, num_entries, max_entries))
>                  num_entries = max_entries;
>
> -       scratch_pte = gen8_pte_encode(vm->scratch.addr,
> +       scratch_pte = gen8_pte_encode(px_dma(vm->scratch_page),
>                                        I915_CACHE_LLC,
>                                        use_scratch);
>          for (i = 0; i < num_entries; i++)
> @@ -1900,7 +1910,8 @@ static void gen6_ggtt_clear_range(struct i915_address_space *vm,
>                   first_entry, num_entries, max_entries))
>                  num_entries = max_entries;
>
> -       scratch_pte = vm->pte_encode(vm->scratch.addr, I915_CACHE_LLC, use_scratch, 0);
> +       scratch_pte = vm->pte_encode(px_dma(vm->scratch_page),
> +                                    I915_CACHE_LLC, use_scratch, 0);
>
>          for (i = 0; i < num_entries; i++)
>                  iowrite32(scratch_pte, &gtt_base[i]);
> @@ -2157,42 +2168,40 @@ void i915_global_gtt_cleanup(struct drm_device *dev)
>          vm->cleanup(vm);
>   }
>
> -static int setup_scratch_page(struct drm_device *dev)
> +static int alloc_scratch_page(struct i915_address_space *vm)
>   {
> -       struct drm_i915_private *dev_priv = dev->dev_private;
> -       struct page *page;
> -       dma_addr_t dma_addr;
> +       struct i915_page_scratch *sp;
> +       int ret;
> +
> +       WARN_ON(vm->scratch_page);
>
> -       page = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
> -       if (page == NULL)
> +       sp = kzalloc(sizeof(*sp), GFP_KERNEL);
> +       if (sp == NULL)
>                  return -ENOMEM;
> -       set_pages_uc(page, 1);
>
> -#ifdef CONFIG_INTEL_IOMMU
> -       dma_addr = pci_map_page(dev->pdev, page, 0, PAGE_SIZE,
> -                               PCI_DMA_BIDIRECTIONAL);
> -       if (pci_dma_mapping_error(dev->pdev, dma_addr)) {
> -               __free_page(page);
> -               return -EINVAL;
> +       ret = __setup_page_dma(vm->dev, px_base(sp), GFP_DMA32 | __GFP_ZERO);
> +       if (ret) {
> +               kfree(sp);
> +               return ret;
>          }
> -#else
> -       dma_addr = page_to_phys(page);
> -#endif

Should we keep a no-iommu option?
This seems to have been added for gen6 (gtt).

> -       dev_priv->gtt.base.scratch.page = page;
> -       dev_priv->gtt.base.scratch.addr = dma_addr;
> +
> +       set_pages_uc(px_page(sp), 1);
> +
> +       vm->scratch_page = sp;
>
>          return 0;
>   }
>
> -static void teardown_scratch_page(struct drm_device *dev)
> +static void free_scratch_page(struct i915_address_space *vm)
>   {
> -       struct drm_i915_private *dev_priv = dev->dev_private;
> -       struct page *page = dev_priv->gtt.base.scratch.page;
> +       struct i915_page_scratch *sp = vm->scratch_page;
>
> -       set_pages_wb(page, 1);
> -       pci_unmap_page(dev->pdev, dev_priv->gtt.base.scratch.addr,
> -                      PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
> -       __free_page(page);
> +       set_pages_wb(px_page(sp), 1);
> +
> +       cleanup_px(vm->dev, sp);
> +       kfree(sp);
> +
> +       vm->scratch_page = NULL;
>   }
>
>   static unsigned int gen6_get_total_gtt_size(u16 snb_gmch_ctl)
> @@ -2300,7 +2309,7 @@ static int ggtt_probe_common(struct drm_device *dev,
>                  return -ENOMEM;
>          }
>
> -       ret = setup_scratch_page(dev);
> +       ret = alloc_scratch_page(&dev_priv->gtt.base);
>          if (ret) {
>                  DRM_ERROR("Scratch setup failed\n");
>                  /* iounmap will also get called at remove, but meh */
> @@ -2479,7 +2488,7 @@ static void gen6_gmch_remove(struct i915_address_space *vm)
>          struct i915_gtt *gtt = container_of(vm, struct i915_gtt, base);
>
>          iounmap(gtt->gsm);
> -       teardown_scratch_page(vm->dev);
> +       free_scratch_page(vm);
>   }
>
>   static int i915_gmch_probe(struct drm_device *dev,
> @@ -2543,13 +2552,13 @@ int i915_gem_gtt_init(struct drm_device *dev)
>                  dev_priv->gtt.base.cleanup = gen6_gmch_remove;
>          }
>
> +       gtt->base.dev = dev;
> +
>          ret = gtt->gtt_probe(dev, &gtt->base.total, &gtt->stolen_size,
>                               &gtt->mappable_base, &gtt->mappable_end);
>          if (ret)
>                  return ret;
>
> -       gtt->base.dev = dev;
> -
>          /* GMADR is the PCI mmio aperture into the global GTT. */
>          DRM_INFO("Memory usable by graphics device = %lluM\n",
>                   gtt->base.total >> 20);
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> index 006b839..1fd4041 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> @@ -217,6 +217,10 @@ struct i915_page_dma {
>   #define px_page(px) (px_base(px)->page)
>   #define px_dma(px) (px_base(px)->daddr)
>
> +struct i915_page_scratch {
> +       struct i915_page_dma base;
> +};
> +
>   struct i915_page_table {
>          struct i915_page_dma base;
>
> @@ -243,10 +247,7 @@ struct i915_address_space {
>          u64 start;              /* Start offset always 0 for dri2 */
>          u64 total;              /* size addr space maps (ex. 2GB for ggtt) */
>
> -       struct {
> -               dma_addr_t addr;
> -               struct page *page;
> -       } scratch;
> +       struct i915_page_scratch *scratch_page;
>
>          /**
>           * List of objects currently involved in rendering.
> --
> 1.9.1
>
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