Re: [Intel-gfx] [PATCH v2] drm/i915/ttm: implement access_memory

[Andi Shyti <andi.shyti@linux.intel.com>]

Hi Matt,

[...]

> +static int i915_ttm_access_memory(struct ttm_buffer_object *bo,
> +				  unsigned long offset, void *buf,
> +				  int len, int write)
> +{
> +	struct drm_i915_gem_object *obj = i915_ttm_to_gem(bo);
> +	resource_size_t iomap = obj->mm.region->iomap.base -
> +		obj->mm.region->region.start;
> +	unsigned long page = offset >> PAGE_SHIFT;
> +	unsigned long bytes_left = len;
> +
> +	/*
> +	 * TODO: For now just let it fail if the resource is non-mappable,
> +	 * otherwise we need to perform the memcpy from the gpu here, without
> +	 * interfering with the object (like moving the entire thing).
> +	 */
> +	if (!i915_ttm_resource_mappable(bo->resource))
> +		return -EIO;
> +
> +	offset -= page << PAGE_SHIFT;
> +	do {
> +		unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
> +		void __iomem *ptr;
> +		dma_addr_t daddr;
> +
> +		daddr = i915_gem_object_get_dma_address(obj, page);
> +		ptr = ioremap_wc(iomap + daddr + offset, PAGE_SIZE);

PAGE_SIZE or bytes? We don't know what there is after "bytes".

Andi

> +		if (!ptr)
> +			return -EIO;
> +
> +		if (write)
> +			memcpy_toio(ptr, buf, bytes);
> +		else
> +			memcpy_fromio(buf, ptr, bytes);
> +		iounmap(ptr);
> +
> +		page++;
> +		buf += bytes;
> +		bytes_left -= bytes;
> +		offset = 0;
> +	} while (bytes_left);
> +
> +	return len;
> +}