mxs/dma: Enlarge the CCW descriptor area to 4 pages

In case of a large SPI flash, the amount of DMA descriptors
available to the DMA driver is not large enough anymore. For
example 8MB SPI flash now needs 129 descriptors to be transfered
in one long read. There are currently 53 descriptors available in
one PAGE_SIZE-big block. Enlarge the allocated descriptor area to
four PAGE_SIZE blocks to fulfill such requirements.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Dan Williams <djbw@fb.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>

drivers/dma/mxs-dma.c

@@ -101,7 +101,8 @@ struct mxs_dma_ccw {
 	u32		pio_words[MXS_PIO_WORDS];
 };
 
-#define NUM_CCW	(int)(PAGE_SIZE / sizeof(struct mxs_dma_ccw))
+#define CCW_BLOCK_SIZE	(4 * PAGE_SIZE)
+#define NUM_CCW	(int)(CCW_BLOCK_SIZE / sizeof(struct mxs_dma_ccw))
 
 struct mxs_dma_chan {
 	struct mxs_dma_engine		*mxs_dma;
@@ -354,14 +355,15 @@ static int mxs_dma_alloc_chan_resources(struct dma_chan *chan)
 
 	mxs_chan->chan_irq = data->chan_irq;
 
-	mxs_chan->ccw = dma_alloc_coherent(mxs_dma->dma_device.dev, PAGE_SIZE,
-				&mxs_chan->ccw_phys, GFP_KERNEL);
+	mxs_chan->ccw = dma_alloc_coherent(mxs_dma->dma_device.dev,
+				CCW_BLOCK_SIZE, &mxs_chan->ccw_phys,
+				GFP_KERNEL);
 	if (!mxs_chan->ccw) {
 		ret = -ENOMEM;
 		goto err_alloc;
 	}
 
-	memset(mxs_chan->ccw, 0, PAGE_SIZE);
+	memset(mxs_chan->ccw, 0, CCW_BLOCK_SIZE);
 
 	if (mxs_chan->chan_irq != NO_IRQ) {
 		ret = request_irq(mxs_chan->chan_irq, mxs_dma_int_handler,
@@ -387,7 +389,7 @@ static int mxs_dma_alloc_chan_resources(struct dma_chan *chan)
 err_clk:
 	free_irq(mxs_chan->chan_irq, mxs_dma);
 err_irq:
-	dma_free_coherent(mxs_dma->dma_device.dev, PAGE_SIZE,
+	dma_free_coherent(mxs_dma->dma_device.dev, CCW_BLOCK_SIZE,
 			mxs_chan->ccw, mxs_chan->ccw_phys);
 err_alloc:
 	return ret;
@@ -402,7 +404,7 @@ static void mxs_dma_free_chan_resources(struct dma_chan *chan)
 
 	free_irq(mxs_chan->chan_irq, mxs_dma);
 
-	dma_free_coherent(mxs_dma->dma_device.dev, PAGE_SIZE,
+	dma_free_coherent(mxs_dma->dma_device.dev, CCW_BLOCK_SIZE,
 			mxs_chan->ccw, mxs_chan->ccw_phys);
 
 	clk_disable_unprepare(mxs_dma->clk);