[Intel-gfx] [PATCH 03/17] drm/i915: align the vma start to the gtt page size

[Chris Wilson]

On Tue, May 16, 2017 at 09:29:34AM +0100, Matthew Auld wrote:
> When inserting into a 48bit PPGTT we need to align the vma start address
> to the required page size boundary. The size will already be aligned so
> no padding is needed.
> 
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_vma.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 1aba47024656..53f6c94b2ee6 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -471,6 +471,14 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
>  	if (ret)
>  		return ret;
>  
> +	if (i915_vm_is_48bit(vma->vm) &&
> +	    obj->gtt_page_size > I915_GTT_PAGE_SIZE) {
> +		unsigned int page_alignment = obj->gtt_page_size;
> +
> +		alignment = max_t(typeof(alignment), alignment, page_alignment);
> +		GEM_BUG_ON(!IS_ALIGNED(vma->size, obj->gtt_page_size));
> +	}
> +
>  	if (flags & PIN_OFFSET_FIXED) {

We should only increase the minimum alignment for !FIXED. Otherwise the
softpin user will not know what games we are playing and be able to
compensate.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre