[PATCH] Revert "dma: use dma/cpu conversions correctly in dma_map/unmap_single"

[Sascha Hauer]

This reverts commit d13d870986eeecc58d8652268557e4a159b9d4c4.

While the patch itself is correct, it at least breaks USB on the
Raspberry Pi 3b.

With this patch dma_sync_single_for_device() is passed the DMA address.
This is correct as even the prototype suggests that it should get a
dma_addr_t. Unfortunately this is not what the function implements and
also not what the users expect. Most if not all users simply pass a CPU
pointer casted to unsigned long. dma_sync_single_for_device() on ARM
then takes the DMA address as a CPU pointer and does cache maintenance
on it.

Before we can merge this patch again dma_sync_single_for_device() must
get a struct device * argument and (on ARM) the cpu_to_dma() conversion
must be reverted before doing cache maintenance.
---
 drivers/dma/map.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/map.c b/drivers/dma/map.c
index fea04c38a3..114c0f7db3 100644
--- a/drivers/dma/map.c
+++ b/drivers/dma/map.c
@@ -23,15 +23,17 @@ static inline void *dma_to_cpu(struct device *dev, dma_addr_t addr)
 dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
 			  enum dma_data_direction dir)
 {
-	dma_addr_t ret = cpu_to_dma(dev, ptr);
+	unsigned long addr = (unsigned long)ptr;
 
-	dma_sync_single_for_device(ret, size, dir);
+	dma_sync_single_for_device(addr, size, dir);
 
-	return ret;
+	return cpu_to_dma(dev, ptr);
 }
 
 void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 		      enum dma_data_direction dir)
 {
-	dma_sync_single_for_cpu(dma_addr, size, dir);
+	unsigned long addr = (unsigned long)dma_to_cpu(dev, dma_addr);
+
+	dma_sync_single_for_cpu(addr, size, dir);
 }
-- 
2.39.2