mmc/dw_mmc: Fix DMA descriptor corruption

In dwmci_prepare_data, the descriptors are allocated for DMA transfer. These are allocated using the ALLOC_CACHE_ALIGN_BUFFER. This macro uses the stack to allocate these descriptors. This becomes a problem if the DMA transfer continues after the processor leaves the function in which the descriptors were allocated.

Therefore, I have moved the allocated of the buffers up one level, to dwmci_send_cmd(). The DMA transfer should be complete when leaving this function.

Signed-off-by Mischa Jonker <[email protected]>

Cc Alexey Brodkin <[email protected]>

Cc Jaehoon Chung <[email protected]>

Cc Andy Fleming <[email protected]>

---
 drivers/mmc/dw_mmc.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

drivers/mmc/dw_mmc.c +4 -3

index a82ee17..796a811 100644
@@ -41,12 +41,11 @@ static void dwmci_set_idma_desc(struct dwmci_idmac *idmac,
 }
 
 static void dwmci_prepare_data(struct dwmci_host *host,
-		struct mmc_data *data)
+		struct mmc_data *data, struct dwmci_idmac *cur_idmac)
 {
 	unsigned long ctrl;
 	unsigned int i = 0, flags, cnt, blk_cnt;
 	ulong data_start, data_end, start_addr;
-	ALLOC_CACHE_ALIGN_BUFFER(struct dwmci_idmac, cur_idmac, data->blocks);
 
 
 	blk_cnt = data->blocks;

@@ -111,6 +110,8 @@ static int dwmci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
 		struct mmc_data *data)
 {
 	struct dwmci_host *host = (struct dwmci_host *)mmc->priv;
+	ALLOC_CACHE_ALIGN_BUFFER(struct dwmci_idmac, cur_idmac,
+				 data ? data->blocks : 0);
 	int flags = 0, i;
 	unsigned int timeout = 100000;
 	u32 retry = 10000;

@@ -127,7 +128,7 @@ static int dwmci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
 	dwmci_writel(host, DWMCI_RINTSTS, DWMCI_INTMSK_ALL);
 
 	if (data)
-		dwmci_prepare_data(host, data);
+		dwmci_prepare_data(host, data, cur_idmac);
 
 	dwmci_writel(host, DWMCI_CMDARG, cmd->cmdarg);
 

In dwmci_prepare_data, the descriptors are allocated for DMA transfer. These are allocated using the ALLOC_CACHE_ALIGN_BUFFER. This macro uses the stack to allocate these descriptors. This becomes a problem if the DMA transfer continues after the processor leaves the function in which the descriptors were allocated.

Therefore, I have moved the allocated of the buffers up one level, to dwmci_send_cmd(). The DMA transfer should be complete when leaving this function.

Signed-off-by Mischa Jonker <[email protected]>

Cc Alexey Brodkin <[email protected]>

Cc Jaehoon Chung <[email protected]>

Cc Andy Fleming <[email protected]>