dmaengine: imx-sdma: Save imx_dma_data into sdmac

The filter() function is currently called by xlate() while it transfers
imx_dma_data as a local variable to the filter() but releases the data
right after returning a DMA channel pointer, which results chan->private
pointing an invalid memory space.

So this patch just stores the imx_dma_data into sdmac to make usre the
private pointer valid as long as the channel exists.
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/imx-sdma.c

@@ -271,6 +271,7 @@ struct sdma_channel {
 	unsigned int			chn_count;
 	unsigned int			chn_real_count;
 	struct tasklet_struct		tasklet;
+	struct imx_dma_data		data;
 };
 
 #define IMX_DMA_SG_LOOP		BIT(0)
@@ -1413,12 +1414,14 @@ static int __init sdma_init(struct sdma_engine *sdma)
 
 static bool sdma_filter_fn(struct dma_chan *chan, void *fn_param)
 {
+	struct sdma_channel *sdmac = to_sdma_chan(chan);
 	struct imx_dma_data *data = fn_param;
 
 	if (!imx_dma_is_general_purpose(chan))
 		return false;
 
-	chan->private = data;
+	sdmac->data = *data;
+	chan->private = &sdmac->data;
 
 	return true;
 }