dmaengine: dw: Don't pollute CTL_LO on iDMA 32-bit

Intel iDMA 32-bit doesn't have a concept of bus masters and thus
there is no need to setup any kind of masters in the CTL_LO register.

Moreover, the burst size for memory-to-memory transfer is not what is says,
we need to have a corrected list of possible sizes. Note, that
the size of 8 items, each of that up to 4 bytes, is chosen because of
maximum of 1/2 FIFO, which is 64 bytes on Intel Merrifield.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/dw/dw.c

@@ -4,6 +4,7 @@
 // Copyright (C) 2013,2018 Intel Corporation
 
 #include <linux/bitops.h>
+#include <linux/dmaengine.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
 #include <linux/types.h>
@@ -63,6 +64,22 @@ static size_t dw_dma_block2bytes(struct dw_dma_chan *dwc, u32 block, u32 width)
 	return DWC_CTLH_BLOCK_TS(block) << width;
 }
 
+static u32 dw_dma_prepare_ctllo(struct dw_dma_chan *dwc)
+{
+	struct dma_slave_config	*sconfig = &dwc->dma_sconfig;
+	bool is_slave = is_slave_direction(dwc->direction);
+	u8 smsize = is_slave ? sconfig->src_maxburst : DW_DMA_MSIZE_16;
+	u8 dmsize = is_slave ? sconfig->dst_maxburst : DW_DMA_MSIZE_16;
+	u8 p_master = dwc->dws.p_master;
+	u8 m_master = dwc->dws.m_master;
+	u8 dms = (dwc->direction == DMA_MEM_TO_DEV) ? p_master : m_master;
+	u8 sms = (dwc->direction == DMA_DEV_TO_MEM) ? p_master : m_master;
+
+	return DWC_CTLL_LLP_D_EN | DWC_CTLL_LLP_S_EN |
+	       DWC_CTLL_DST_MSIZE(dmsize) | DWC_CTLL_SRC_MSIZE(smsize) |
+	       DWC_CTLL_DMS(dms) | DWC_CTLL_SMS(sms);
+}
+
 static void dw_dma_encode_maxburst(struct dw_dma_chan *dwc, u32 *maxburst)
 {
 	/*
@@ -99,6 +116,7 @@ int dw_dma_probe(struct dw_dma_chip *chip)
 	dw->initialize_chan = dw_dma_initialize_chan;
 	dw->suspend_chan = dw_dma_suspend_chan;
 	dw->resume_chan = dw_dma_resume_chan;
+	dw->prepare_ctllo = dw_dma_prepare_ctllo;
 	dw->encode_maxburst = dw_dma_encode_maxburst;
 	dw->bytes2block = dw_dma_bytes2block;
 	dw->block2bytes = dw_dma_block2bytes;