linux-kernel - [PATCH] staging: ion: Add a default struct device for cma heap

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Date:	Thu,  6 Aug 2015 18:24:58 +0800
From:	Feng Tang <feng.tang@...el.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	John Stultz <john.stultz@...aro.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Nazarewicz <mina86@...a86.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	linux-kernel@...r.kernel.org
Cc:	Feng Tang <feng.tang@...el.com>
Subject: [PATCH] staging: ion: Add a default struct device for cma heap

When trying to use several cma heaps on our platforms,
we met a memory issue due to that the several cma_heaps
are sharing the same "struct device *".

As in current code base, the normal cma heap creating
process is, one platform device is created during boot,
and it will sequentially create cma heaps (usually passing
its own struct device * as a parameter)

For the multiple cma heaps case, there will be one "struct
cma" created for each cma heap, and this "struct cma *" is
saved in dev->cma_area. So the single platform device can't
meet the requirement here.

So this patch add one default device for a cma heap to avoid
sharing the same "struct device", thus fix the issue. And it
doesn't break existing code by only using that default device
when no "struct device *" is passed in.

Also, since the cma framework has been cleaned up, this patch
also add a platform data member to pass the "struct cma*" to
ion_cma_heap_create().

Signed-off-by: Feng Tang <feng.tang@...el.com>
---
 drivers/staging/android/ion/ion.h          |    4 ++++
 drivers/staging/android/ion/ion_cma_heap.c |   20 +++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h
index 443db84..e9af17e 100644
--- a/drivers/staging/android/ion/ion.h
+++ b/drivers/staging/android/ion/ion.h
@@ -45,6 +45,9 @@ struct ion_buffer;
  * @size:	size of the heap in bytes if applicable
  * @align:	required alignment in physical memory if applicable
  * @priv:	private info passed from the board file
+ * @priv2:	when creating CMA heap, platform device should better also
+ *		pass the "struct cma *" info, so that the cma buffer request
+ *		know where to go for the buffer
  *
  * Provided by the board file.
  */
@@ -56,6 +59,7 @@ struct ion_platform_heap {
 	size_t size;
 	ion_phys_addr_t align;
 	void *priv;
+	void *priv2;
 };
 
 /**
diff --git a/drivers/staging/android/ion/ion_cma_heap.c b/drivers/staging/android/ion/ion_cma_heap.c
index f4211f1..b3e8896 100644
--- a/drivers/staging/android/ion/ion_cma_heap.c
+++ b/drivers/staging/android/ion/ion_cma_heap.c
@@ -29,6 +29,7 @@
 struct ion_cma_heap {
 	struct ion_heap heap;
 	struct device *dev;
+	struct device default_dma_dev;
 };
 
 #define to_cma_heap(x) container_of(x, struct ion_cma_heap, heap)
@@ -180,9 +181,22 @@ struct ion_heap *ion_cma_heap_create(struct ion_platform_heap *data)
 		return ERR_PTR(-ENOMEM);
 
 	cma_heap->heap.ops = &ion_cma_ops;
-	/* get device from private heaps data, later it will be
-	 * used to make the link with reserved CMA memory */
-	cma_heap->dev = data->priv;
+
+	/*
+	 * data->priv for cma heap is currently supposed to point
+	 * to a "struct device *"
+	 */
+	if (data->priv) {
+		cma_heap->dev = data->priv;
+	} else {
+		cma_heap->dev = &cma_heap->default_dma_dev;
+		cma_heap->dev->coherent_dma_mask = DMA_BIT_MASK(32);
+		cma_heap->dev->dma_mask = &dev->coherent_dma_mask;
+	}
+
+	/* data->priv2 contains a pointer to struct cma */
+	dev_set_cma_area(cma_heap->dev, data->priv2);
+
 	cma_heap->heap.type = ION_HEAP_TYPE_DMA;
 	return &cma_heap->heap;
 }
-- 
1.7.9.5

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