On 16 May 2017 at 10:59, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
> On Tue, May 16, 2017 at 09:29:33AM +0100, Matthew Auld wrote:
>> In preparation for supporting huge gtt pages for the ppgtt, we introduce
>> a gtt_page_size member for gem objects. We fill in the gtt page size by
>> scanning the sg table to determine the max page size which satisfies the
>> alignment for each sg entry.
>>
>> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
>> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
>> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
>> Cc: Daniel Vetter <daniel@xxxxxxxx>
>> ---
>> drivers/gpu/drm/i915/i915_drv.h | 2 ++
>> drivers/gpu/drm/i915/i915_gem.c | 23 +++++++++++++++++++++++
>> drivers/gpu/drm/i915/i915_gem_object.h | 2 ++
>> 3 files changed, 27 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>> index e18f11f77f35..a7a108d18a2d 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -2843,6 +2843,8 @@ intel_info(const struct drm_i915_private *dev_priv)
>> #define USES_PPGTT(dev_priv) (i915.enable_ppgtt)
>> #define USES_FULL_PPGTT(dev_priv) (i915.enable_ppgtt >= 2)
>> #define USES_FULL_48BIT_PPGTT(dev_priv) (i915.enable_ppgtt == 3)
>> +#define HAS_PAGE_SIZE(dev_priv, page_size) \
>> + ((dev_priv)->info.page_size_mask & (page_size))
>>
>> #define HAS_OVERLAY(dev_priv) ((dev_priv)->info.has_overlay)
>> #define OVERLAY_NEEDS_PHYSICAL(dev_priv) \
>> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
>> index 0c1cbe98c994..6a5e864d7710 100644
>> --- a/drivers/gpu/drm/i915/i915_gem.c
>> +++ b/drivers/gpu/drm/i915/i915_gem.c
>> @@ -2294,6 +2294,8 @@ void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj,
>> if (!IS_ERR(pages))
>> obj->ops->put_pages(obj, pages);
>>
>> + obj->gtt_page_size = 0;
>> +
>> unlock:
>> mutex_unlock(&obj->mm.lock);
>> }
>> @@ -2473,6 +2475,13 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
>> void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
>> struct sg_table *pages)
>> {
>> + struct drm_i915_private *i915 = to_i915(obj->base.dev);
>> + unsigned long supported_page_sizes = INTEL_INFO(i915)->page_size_mask;
>> + struct scatterlist *sg;
>> + unsigned int sg_mask = 0;
>> + unsigned int i;
>> + unsigned int bit;
>> +
>> lockdep_assert_held(&obj->mm.lock);
>>
>> obj->mm.get_page.sg_pos = pages->sgl;
>> @@ -2486,6 +2495,20 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
>> __i915_gem_object_pin_pages(obj);
>> obj->mm.quirked = true;
>> }
>> +
>> + for_each_sg(pages->sgl, sg, pages->nents, i)
>> + sg_mask |= sg->length;
>> +
>> + GEM_BUG_ON(!sg_mask);
>> +
>
> This should just be obj->gtt_page_sizes = sg_mask & supported_sizes;
But wouldn't this assume that sg->length is exactly a page size, I
would have imagined it would be possible for shmem to give us two or
more continuous super-pages, or am I missing something?
>
> And it should be obj->mm.gtt_page_sizes.
>
> Then latter steps can make decisions based on the most strict
> requirements, or least strict etc.
> -Chris
>
> --
> Chris Wilson, Intel Open Source Technology Centre
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
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