[PATCH 4/6] dmaengine: mxs: switch from dma_coherent to dma_pool

[Han Xu]

create one dma_pool dedicate for mxs-dma to avoid the
"alloc_contig_range: [xxx, xxx) PFNs busy" warning message during
frequently alloc/free resource ops in runtime pm.

Signed-off-by: Han Xu <han.xu@xxxxxxx>
---
 drivers/dma/mxs-dma.c | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
index 251492c5ea58..dfee41ae1981 100644
--- a/drivers/dma/mxs-dma.c
+++ b/drivers/dma/mxs-dma.c
@@ -26,6 +26,7 @@
 #include <linux/list.h>
 #include <linux/dma/mxs-dma.h>
 #include <linux/pm_runtime.h>
+#include <linux/dmapool.h>
 
 #include <asm/irq.h>
 
@@ -121,6 +122,7 @@ struct mxs_dma_chan {
 	enum dma_status			status;
 	unsigned int			flags;
 	bool				reset;
+	struct dma_pool			*ccw_pool;
 #define MXS_DMA_SG_LOOP			(1 << 0)
 #define MXS_DMA_USE_SEMAPHORE		(1 << 1)
 };
@@ -422,9 +424,10 @@ static int mxs_dma_alloc_chan_resources(struct dma_chan *chan)
 	struct device *dev = &mxs_dma->pdev->dev;
 	int ret;
 
-	mxs_chan->ccw = dma_alloc_coherent(mxs_dma->dma_device.dev,
-					   CCW_BLOCK_SIZE,
-					   &mxs_chan->ccw_phys, GFP_KERNEL);
+	mxs_chan->ccw = dma_pool_zalloc(mxs_chan->ccw_pool,
+					GFP_ATOMIC,
+					&mxs_chan->ccw_phys);
+
 	if (!mxs_chan->ccw) {
 		ret = -ENOMEM;
 		goto err_alloc;
@@ -454,8 +457,8 @@ 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, CCW_BLOCK_SIZE,
-			mxs_chan->ccw, mxs_chan->ccw_phys);
+	dma_pool_free(mxs_chan->ccw_pool, mxs_chan->ccw,
+		      mxs_chan->ccw_phys);
 err_alloc:
 	return ret;
 }
@@ -470,8 +473,8 @@ 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, CCW_BLOCK_SIZE,
-			mxs_chan->ccw, mxs_chan->ccw_phys);
+	dma_pool_free(mxs_chan->ccw_pool, mxs_chan->ccw,
+		      mxs_chan->ccw_phys);
 
 	pm_runtime_mark_last_busy(dev);
 	pm_runtime_put_autosuspend(dev);
@@ -796,6 +799,7 @@ static int mxs_dma_probe(struct platform_device *pdev)
 	const struct mxs_dma_type *dma_type;
 	struct mxs_dma_engine *mxs_dma;
 	struct resource *iores;
+	struct dma_pool *ccw_pool;
 	int ret, i;
 
 	mxs_dma = devm_kzalloc(&pdev->dev, sizeof(*mxs_dma), GFP_KERNEL);
@@ -843,7 +847,6 @@ static int mxs_dma_probe(struct platform_device *pdev)
 		tasklet_init(&mxs_chan->tasklet, mxs_dma_tasklet,
 			     (unsigned long) mxs_chan);
 
-
 		/* Add the channel to mxs_chan list */
 		list_add_tail(&mxs_chan->chan.device_node,
 			&mxs_dma->dma_device.channels);
@@ -858,6 +861,17 @@ static int mxs_dma_probe(struct platform_device *pdev)
 
 	mxs_dma->dma_device.dev = &pdev->dev;
 
+	/* create the dma pool */
+	ccw_pool = dma_pool_create("ccw_pool",
+				   mxs_dma->dma_device.dev,
+				   CCW_BLOCK_SIZE, 32, 0);
+
+	for (i = 0; i < MXS_DMA_CHANNELS; i++) {
+		struct mxs_dma_chan *mxs_chan = &mxs_dma->mxs_chans[i];
+
+		mxs_chan->ccw_pool = ccw_pool;
+	}
+
 	/* mxs_dma gets 65535 bytes maximum sg size */
 	mxs_dma->dma_device.dev->dma_parms = &mxs_dma->dma_parms;
 	dma_set_max_seg_size(mxs_dma->dma_device.dev, MAX_XFER_BYTES);
@@ -899,11 +913,13 @@ static int mxs_dma_remove(struct platform_device *pdev)
 	int i;
 
 	dma_async_device_unregister(&mxs_dma->dma_device);
+	dma_pool_destroy(mxs_dma->mxs_chans[0].ccw_pool);
 
 	for (i = 0; i < MXS_DMA_CHANNELS; i++) {
 		struct mxs_dma_chan *mxs_chan = &mxs_dma->mxs_chans[i];
 
 		tasklet_kill(&mxs_chan->tasklet);
+		mxs_chan->ccw_pool = NULL;
 	}
 
 	return 0;
-- 
2.17.1