From: "George G. Davis" <[email protected]> When a "linux,dma-default" DMA coherent region is defined, the dma_coherent_default_memory pointer is returned by function dev_get_coherent_memory() for any struct device *dev which has not explicitly assigned a dev->dma_mem memory region, i.e. dev->dma_mem is the NULL pointer. Unfortunately this overlooks the fact that for the CONFIG_DMA_CMA case, it is also possible that a device may have assigned a CMA memory region via the dev->cma_area pointer in which case, the "linux,dma-default" DMA coherent region should not be used. Since the current code did not consider this case, dev->cma_area regions are not used when a "linux,dma-default" DMA coherent region is defined. Instead, memory is allocated from the "linux,dma-default" DMA coherent region. This omission could lead to DMA memory allocation failures for devices such as the "viv,galcore" which require a large contiguous address space which cannot be supplied by the "linux,dma-default" region IFF it has been reconfigured to use a CMA memory region. Similar DMA allocation failures are likely to occur for other devices which require large memory regions and/or overall allocation requests exceed the size of the "linux,dma-default" DMA coherent region size.
Fix this by updating the dev_get_coherent_memory() function to return the NULL pointer if a dev->cma_area region is assigned to a device. Cc: Greg Kroah-Hartman <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Marek Szyprowski <[email protected]> Cc: Robin Murphy <[email protected]> Signed-off-by: George G. Davis <[email protected]> Signed-off-by: Vitaly Kuzmichev <[email protected]> --- drivers/base/dma-coherent.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c index 2ae24c2..acfe140 100644 --- a/drivers/base/dma-coherent.c +++ b/drivers/base/dma-coherent.c @@ -25,6 +25,10 @@ static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *de { if (dev && dev->dma_mem) return dev->dma_mem; +#ifdef CONFIG_DMA_CMA + if (dev && dev->cma_area) + return NULL; +#endif return dma_coherent_default_memory; } -- 1.9.1
