From dc9b60552f6a6a56b1defb88aa9f7f1498fcc045 Mon Sep 17 00:00:00 2001
From: Peter Ujfalusi <peter.ujfalusi@ti.com>
Date: Wed, 14 Oct 2015 14:42:47 +0300
Subject: [PATCH] ARM/dmaengine: edma: Move of_dma_controller_register to the
 dmaengine driver

If the of_dma_controller is registered in the non dmaengine driver we could
have race condition:
the of_dma_controller has been registered, but the dmaengine driver is not
yet probed. Drivers requesting DMA channels during this window will fail
since we do not yet have dmaengine drivers registered.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
---
 arch/arm/common/edma.c | 10 ----------
 drivers/dma/edma.c     | 16 ++++++++++++++++
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/arch/arm/common/edma.c b/arch/arm/common/edma.c
index 7c2fe527e53b..d82fceda13a3 100644
--- a/arch/arm/common/edma.c
+++ b/arch/arm/common/edma.c
@@ -29,7 +29,6 @@
 #include <linux/dma-mapping.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
-#include <linux/of_dma.h>
 #include <linux/of_irq.h>
 #include <linux/pm_runtime.h>
 
@@ -1191,10 +1190,6 @@ static int edma_of_parse_dt(struct device *dev,
 	return ret;
 }
 
-static struct of_dma_filter_info edma_filter_info = {
-	.filter_fn = edma_filter_fn,
-};
-
 static struct edma_soc_info *edma_setup_info_from_dt(struct device *dev,
 						      struct device_node *node)
 {
@@ -1209,11 +1204,6 @@ static struct edma_soc_info *edma_setup_info_from_dt(struct device *dev,
 	if (ret)
 		return ERR_PTR(ret);
 
-	dma_cap_set(DMA_SLAVE, edma_filter_info.dma_cap);
-	dma_cap_set(DMA_CYCLIC, edma_filter_info.dma_cap);
-	of_dma_controller_register(dev->of_node, of_dma_simple_xlate,
-				   &edma_filter_info);
-
 	return info;
 }
 #else
diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 19fa49d6f555..fcb4680efed7 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -25,6 +25,7 @@
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/of.h>
+#include <linux/of_dma.h>
 
 #include <linux/platform_data/edma.h>
 
@@ -987,9 +988,14 @@ static void edma_dma_init(struct edma_cc *ecc, struct dma_device *dma,
 	INIT_LIST_HEAD(&dma->channels);
 }
 
+static struct of_dma_filter_info edma_filter_info = {
+	.filter_fn = edma_filter_fn,
+};
+
 static int edma_probe(struct platform_device *pdev)
 {
 	struct edma_cc *ecc;
+	struct device_node *parent_node = pdev->dev.parent->of_node;
 	int ret;
 
 	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
@@ -1024,6 +1030,13 @@ static int edma_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, ecc);
 
+	if (parent_node) {
+		dma_cap_set(DMA_SLAVE, edma_filter_info.dma_cap);
+		dma_cap_set(DMA_CYCLIC, edma_filter_info.dma_cap);
+		of_dma_controller_register(parent_node, of_dma_simple_xlate,
+					   &edma_filter_info);
+	}
+
 	dev_info(&pdev->dev, "TI EDMA DMA engine driver\n");
 
 	return 0;
@@ -1037,7 +1050,10 @@ static int edma_remove(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct edma_cc *ecc = dev_get_drvdata(dev);
+	struct device_node *parent_node = pdev->dev.parent->of_node;
 
+	if (parent_node)
+		of_dma_controller_free(parent_node);
 	dma_async_device_unregister(&ecc->dma_slave);
 	edma_free_slot(ecc->dummy_slot);