[PATCH 4/9] spi: sun4i: add DMA support

[Mark Brown]

On Thu, Aug 20, 2015 at 02:19:46PM -0000, Emilio López wrote:

> -	sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
> +	if (sun4i_spi_can_dma(master, spi, tfr) && desc_rx) {
> +		/* The receive transfer should be the last one to finish */
> +		dma_wait_for_async_tx(desc_rx);

What if it's a transmit only transfer?  We'll fall over to this...

> +	} else {
> +		sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
> +	}

...which manually reads data from the FIFO which doesn't seem like what
we want, won't it conflict with the DMA?
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