[PATCH net/next 3/3] net: ethernet: mtk_eth_soc: use genpool allocator for SRAM

[Andrew Lunn]

> +static void *mtk_dma_ring_alloc(struct mtk_eth *eth, size_t size,
> +				dma_addr_t *dma_handle)
> +{
> +	void *dma_ring;
> +
> +	if (WARN_ON(mtk_use_legacy_sram(eth)))
> +		return -ENOMEM;
> +
> +	if (eth->sram_pool) {
> +		dma_ring = (void *)gen_pool_alloc(eth->sram_pool, size);
> +		if (!dma_ring)
> +			return dma_ring;
> +		*dma_handle = gen_pool_virt_to_phys(eth->sram_pool, (unsigned long)dma_ring);

I don't particularly like all the casting backwards and forwards
between unsigned long and void *. These two APIs are not really
compatible with each other. So any sort of wrapping is going to be
messy.

Maybe define a cookie union:

struct mtk_dma_cookie {
	union {
		unsigned long gen_pool;
		void *coherent;
	}
}

Only dma_handle appears to be used by the rest of the code, so only
the _alloc and _free need to know about the union.

	Andrew