[PATCH 16/34] drm: kselftest for drm_mm and top-down alignment

[Joonas Lahtinen]

On ma, 2016-12-12 at 11:53 +0000, Chris Wilson wrote:
> Check that if we request top-down allocation with a particular alignment
> from drm_mm_insert_node() that the start of the node matches our
> request.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Assuming magic numbers be gone in next iteration.

> +static int igt_topdown_align(void *ignored)
> +{
> +	struct drm_mm mm;
> +	struct drm_mm_node tmp, resv;
> +	int ret = -EINVAL;
> +	int n, m, err;
> +
> +	drm_mm_init(&mm, 0, ~0ull);
> +	memset(&tmp, 0, sizeof(tmp));
> +	memset(&resv, 0, sizeof(resv));
> +
> +	for (m = 0; m < 32; m++) {
> +		u64 end = ~0ull;
> +
> +		if (m) {
> +			resv.size = BIT_ULL(m);
> +			end -= resv.size;
> +			resv.start = end;
> +
> +			err = drm_mm_reserve_node(&mm, &resv);
> +			if (err) {
> +				pr_err("reservation of sentinel node failed\n");
> +				ret = err;
> +				goto out;
> +			}
> +		}
> +
> +		for (n = 0; n < 63 - m; n++) {
> +			u64 align = BIT_ULL(n);

DRM_MM_BUG_ON(end % align); to protect somebody from modifying? (or end
& (align - 1))

> +
> +			err = drm_mm_insert_node_generic(&mm, &tmp, 1, align, 0,
> +							 DRM_MM_SEARCH_BELOW,
> +							 DRM_MM_CREATE_TOP);
> +			drm_mm_remove_node(&tmp);

Could move this after if (err) again and in the rest of the code, too.

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation