[Intel-gfx] [PATCH v3 23/37] drm/i915: do not map aperture if it is not available.

[Chris Wilson]

Quoting Matthew Auld (2019-08-09 23:26:29)
> From: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> 
> Skip both setup and cleanup of the aperture mapping if the HW doesn't
> have an aperture bar.
> 
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> Cc: Matthew Auld <matthew.auld at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_gtt.c | 36 ++++++++++++++++++-----------
>  1 file changed, 22 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 5bcf71b18e5f..dd28c54527e3 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -2795,8 +2795,10 @@ static void ggtt_cleanup_hw(struct i915_ggtt *ggtt)
>  
>         mutex_unlock(&i915->drm.struct_mutex);
>  
> -       arch_phys_wc_del(ggtt->mtrr);
> -       io_mapping_fini(&ggtt->iomap);
> +       if (HAS_MAPPABLE_APERTURE(i915)) {

I feel here it should be less shouting.

> +               arch_phys_wc_del(ggtt->mtrr);

wc_del() doesn't care if we call it without a mtrr (nothing has been
using an mtrr since PAT).

if (ggtt->iomap.size)
> +               io_mapping_fini(&ggtt->iomap);

> +       }
>  }
>  
>  /**
> @@ -2992,10 +2994,13 @@ static int gen8_gmch_probe(struct i915_ggtt *ggtt)
>         int err;
>  
>         /* TODO: We're not aware of mappable constraints on gen8 yet */
> -       ggtt->gmadr =
> -               (struct resource) DEFINE_RES_MEM(pci_resource_start(pdev, 2),
> -                                                pci_resource_len(pdev, 2));
> -       ggtt->mappable_end = resource_size(&ggtt->gmadr);
> +       /* FIXME: We probably need to add do device_info or runtime_info */
> +       if (!HAS_LMEM(dev_priv)) {
> +               ggtt->gmadr =
> +                       (struct resource) DEFINE_RES_MEM(pci_resource_start(pdev, 2),
> +                                                        pci_resource_len(pdev, 2));
> +               ggtt->mappable_end = resource_size(&ggtt->gmadr);
> +       }
>  
>         err = pci_set_dma_mask(pdev, DMA_BIT_MASK(39));
>         if (!err)
> @@ -3220,15 +3225,18 @@ static int ggtt_init_hw(struct i915_ggtt *ggtt)
>         if (!HAS_LLC(i915) && !HAS_PPGTT(i915))
>                 ggtt->vm.mm.color_adjust = i915_gtt_color_adjust;
>  
> -       if (!io_mapping_init_wc(&ggtt->iomap,
> -                               ggtt->gmadr.start,
> -                               ggtt->mappable_end)) {
> -               ggtt->vm.cleanup(&ggtt->vm);
> -               ret = -EIO;
> -               goto out;
> -       }
> +       if (HAS_MAPPABLE_APERTURE(i915)) {
> +               if (!io_mapping_init_wc(&ggtt->iomap,

if (ggtt->mappable_end) {

In this file, we are dealing with the low level details so I would 
prefer less obfuscation.

> +                                       ggtt->gmadr.start,
> +                                       ggtt->mappable_end)) {
> +                       ggtt->vm.cleanup(&ggtt->vm);
> +                       ret = -EIO;
> +                       goto out;
> +               }
>  
> -       ggtt->mtrr = arch_phys_wc_add(ggtt->gmadr.start, ggtt->mappable_end);
> +               ggtt->mtrr = arch_phys_wc_add(ggtt->gmadr.start,
> +                                             ggtt->mappable_end);
> +       }