[PATCH 4.2 056/258] dmaengine: dw: properly read DWC_PARAMS register

[Greg Kroah-Hartman]

4.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

commit 6bea0f6d1c47b07be88dfd93f013ae05fcb3d8bf upstream.

In case we have less than maximum allowed channels (8) and autoconfiguration is
enabled the DWC_PARAMS read is wrong because it uses different arithmetic to
what is needed for channel priority setup.

Re-do the caclulations properly. This now works on AVR32 board well.

Fixes: fed2574b3c9f (dw_dmac: introduce software emulation of LLP transfers)
Cc: yitian.bu@xxxxxxxxxxxxxx
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/dma/dw/core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -1591,7 +1591,6 @@ int dw_dma_probe(struct dw_dma_chip *chi
 	INIT_LIST_HEAD(&dw->dma.channels);
 	for (i = 0; i < nr_channels; i++) {
 		struct dw_dma_chan	*dwc = &dw->chan[i];
-		int			r = nr_channels - i - 1;
 
 		dwc->chan.device = &dw->dma;
 		dma_cookie_init(&dwc->chan);
@@ -1603,7 +1602,7 @@ int dw_dma_probe(struct dw_dma_chip *chi
 
 		/* 7 is highest priority & 0 is lowest. */
 		if (pdata->chan_priority == CHAN_PRIORITY_ASCENDING)
-			dwc->priority = r;
+			dwc->priority = nr_channels - i - 1;
 		else
 			dwc->priority = i;
 
@@ -1622,6 +1621,7 @@ int dw_dma_probe(struct dw_dma_chip *chi
 		/* Hardware configuration */
 		if (autocfg) {
 			unsigned int dwc_params;
+			unsigned int r = DW_DMA_MAX_NR_CHANNELS - i - 1;
 			void __iomem *addr = chip->regs + r * sizeof(u32);
 
 			dwc_params = dma_read_byaddr(addr, DWC_PARAMS);


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