[PATCHv2] dw_dmac: don't exceed AHB master number in dwc_get_data_width

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

The driver's default assumes that hardware has two AHB masters which might be
not true. In such rare cases we have not to exceed a number of the AHB masters
present in the hardware. Thus, the AHB master with highest possible number will
be used to retrieve the data witdh value.

The patch also changes the logic a bit when the master parameter of the
dwc_get_data_width() is out of range. Now the function will return a value
related to the first AHB master.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/dma/dw_dmac.c |   33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index 30ff2a4..561bb9a 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -46,13 +46,29 @@ static inline unsigned int dwc_get_sms(struct dw_dma_slave *slave)
 	return slave ? slave->src_master : 1;
 }
 
+#define SRC_MASTER	0
+#define DST_MASTER	1
+
+static inline unsigned int dwc_get_master(struct dma_chan *chan, int master)
+{
+	struct dw_dma *dw = to_dw_dma(chan->device);
+	struct dw_dma_slave *dws = chan->private;
+	unsigned int m = 0;
+
+	if (master == SRC_MASTER)
+		m = dwc_get_sms(dws);
+	else if (master == DST_MASTER)
+		m = dwc_get_dms(dws);
+
+	return min_t(unsigned int, dw->nr_masters - 1, m);
+}
+
 #define DWC_DEFAULT_CTLLO(_chan) ({				\
-		struct dw_dma_slave *__slave = (_chan->private);	\
 		struct dw_dma_chan *_dwc = to_dw_dma_chan(_chan);	\
 		struct dma_slave_config	*_sconfig = &_dwc->dma_sconfig;	\
 		bool _is_slave = is_slave_direction(_dwc->direction);	\
-		int _dms = dwc_get_dms(__slave);		\
-		int _sms = dwc_get_sms(__slave);		\
+		int _dms = dwc_get_master(_chan, DST_MASTER);		\
+		int _sms = dwc_get_master(_chan, SRC_MASTER);		\
 		u8 _smsize = _is_slave ? _sconfig->src_maxburst :	\
 			DW_DMA_MSIZE_16;			\
 		u8 _dmsize = _is_slave ? _sconfig->dst_maxburst :	\
@@ -73,20 +89,11 @@ static inline unsigned int dwc_get_sms(struct dw_dma_slave *slave)
  */
 #define NR_DESCS_PER_CHANNEL	64
 
-#define SRC_MASTER	0
-#define DST_MASTER	1
-
 static inline unsigned int dwc_get_data_width(struct dma_chan *chan, int master)
 {
 	struct dw_dma *dw = to_dw_dma(chan->device);
-	struct dw_dma_slave *dws = chan->private;
 
-	if (master == SRC_MASTER)
-		return dw->data_width[dwc_get_sms(dws)];
-	else if (master == DST_MASTER)
-		return dw->data_width[dwc_get_dms(dws)];
-
-	return 0;
+	return dw->data_width[dwc_get_master(chan, master)];
 }
 
 /*----------------------------------------------------------------------*/
-- 
1.7.10.4