[PATCH] ARM: Qualify enabling of swiotlb_init()

[Christoph Hellwig]

On Thu, Mar 18, 2021 at 09:03:33PM -0700, Florian Fainelli wrote:
>  #ifdef CONFIG_ARM_LPAE
> +	if (swiotlb_force == SWIOTLB_FORCE ||
> +	    max_pfn > arm_dma_pfn_limit)

Does arm_dma_pfn_limit do the right thing even with the weirdest
remapping ranges?  Maybe a commen here would be useful.

> +		swiotlb_init(1);
> +	else
> +		swiotlb_force = SWIOTLB_NO_FORCE;

Konrad: what do you think of setting swiotlb_force to SWIOTLB_NO_FORCE
and only switching it to SWIOTLB_NORMAL when swiotlb_init* is called?
That kind makes more sense than forcing the callers to do it.

While we're at it, I think swiotlb_force should probably be renamed to
swiotlb_mode or somethng like that.