dmaengine: dw: Fix FIFO size for Intel Merrifield

Intel Merrifield has a reduced size of FIFO used in iDMA 32-bit controller,
i.e. 512 bytes instead of 1024.

Fix this by partitioning it as 64 bytes per channel.

Note, in the future we might switch to 'fifo-size' property instead of
hard coded value.

Fixes: 199244d694 ("dmaengine: dw: add support of iDMA 32-bit hardware")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/dw/core.c

@@ -1059,12 +1059,12 @@ static void dwc_issue_pending(struct dma_chan *chan)
 /*
  * Program FIFO size of channels.
  *
- * By default full FIFO (1024 bytes) is assigned to channel 0. Here we
+ * By default full FIFO (512 bytes) is assigned to channel 0. Here we
  * slice FIFO on equal parts between channels.
  */
 static void idma32_fifo_partition(struct dw_dma *dw)
 {
-	u64 value = IDMA32C_FP_PSIZE_CH0(128) | IDMA32C_FP_PSIZE_CH1(128) |
+	u64 value = IDMA32C_FP_PSIZE_CH0(64) | IDMA32C_FP_PSIZE_CH1(64) |
 		    IDMA32C_FP_UPDATE;
 	u64 fifo_partition = 0;
 
@@ -1077,7 +1077,7 @@ static void idma32_fifo_partition(struct dw_dma *dw)
 	/* Fill FIFO_PARTITION high bits (Channels 2..3, 6..7) */
 	fifo_partition |= value << 32;
 
-	/* Program FIFO Partition registers - 128 bytes for each channel */
+	/* Program FIFO Partition registers - 64 bytes per channel */
 	idma32_writeq(dw, FIFO_PARTITION1, fifo_partition);
 	idma32_writeq(dw, FIFO_PARTITION0, fifo_partition);
 }