# Re: \[RFC PATCH v3 3/6\] swiotlb: Use restricted DMA pool if available

- From: Christoph Hellwig \<hch@lst.de\>
- Date: 2021-01-13 12:45:07 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2021/01/6233372
- Thread: https://ratatoskr.run/linux-devicetree/2021/01/6224988/t.md

```text
> +#ifdef CONFIG_SWIOTLB
> +	if (unlikely(swiotlb_force == SWIOTLB_FORCE) || dev->dma_io_tlb_mem)
>  		return swiotlb_map(dev, phys, size, dir, attrs);
> +#endif

Please provide a wrapper for the dev->dma_io_tlb_mem check that
always returns false if the per-device swiotlb support is not enabled.

> index 7fb2ac087d23..1f05af09e61a 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -222,7 +222,6 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
>  		mem->orig_addr[i] = INVALID_PHYS_ADDR;
>  	}
>  	mem->index = 0;
> -	no_iotlb_memory = false;

How does this fit in here?

```