dmaengine/dw_dmac: Divide one sg to many desc, if sg len is greater than DWC_MAX_COUNT

If len passed in sg for slave_sg transfers is greater than DWC_MAX_COUNT, then
driver programmes controller incorrectly.  This patch adds code to handle this
situation by allocation more than one desc for same sg.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 44 insertions, 21 deletions

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index f209ff8835e8..a9755e3dd603 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -693,9 +693,15 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                 reg = dws->tx_reg;
                 for_each_sg(sgl, sg, sg_len, i) {
                         struct dw_desc  *desc;
-                        u32             len;
-                        u32             mem;
+                        u32             len, dlen, mem;
 
+                        mem = sg_phys(sg);
+                        len = sg_dma_len(sg);
+                        mem_width = 2;
+                        if (unlikely(mem & 3 || len & 3))
+                                mem_width = 0;
+
+slave_sg_todev_fill_desc:
                         desc = dwc_desc_get(dwc);
                         if (!desc) {
                                 dev_err(chan2dev(chan),
@@ -703,16 +709,19 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                                 goto err_desc_get;
                         }
 
-                        mem = sg_phys(sg);
-                        len = sg_dma_len(sg);
-                        mem_width = 2;
-                        if (unlikely(mem & 3 || len & 3))
-                                mem_width = 0;
-
                         desc->lli.sar = mem;
                         desc->lli.dar = reg;
                         desc->lli.ctllo = ctllo | DWC_CTLL_SRC_WIDTH(mem_width);
-                        desc->lli.ctlhi = len >> mem_width;
+                        if ((len >> mem_width) > DWC_MAX_COUNT) {
+                                dlen = DWC_MAX_COUNT << mem_width;
+                                mem += dlen;
+                                len -= dlen;
+                        } else {
+                                dlen = len;
+                                len = 0;
+                        }
+
+                        desc->lli.ctlhi = dlen >> mem_width;
 
                         if (!first) {
                                 first = desc;
@@ -726,7 +735,10 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                                                 &first->tx_list);
                         }
                         prev = desc;
-                        total_len += len;
+                        total_len += dlen;
+
+                        if (len)
+                                goto slave_sg_todev_fill_desc;
                 }
                 break;
         case DMA_FROM_DEVICE:
@@ -739,15 +751,7 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                 reg = dws->rx_reg;
                 for_each_sg(sgl, sg, sg_len, i) {
                         struct dw_desc  *desc;
-                        u32             len;
-                        u32             mem;
-
-                        desc = dwc_desc_get(dwc);
-                        if (!desc) {
-                                dev_err(chan2dev(chan),
-                                        "not enough descriptors available\n");
-                                goto err_desc_get;
-                        }
+                        u32             len, dlen, mem;
 
                         mem = sg_phys(sg);
                         len = sg_dma_len(sg);
@@ -755,10 +759,26 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                         if (unlikely(mem & 3 || len & 3))
                                 mem_width = 0;
 
+slave_sg_fromdev_fill_desc:
+                        desc = dwc_desc_get(dwc);
+                        if (!desc) {
+                                dev_err(chan2dev(chan),
+                                                "not enough descriptors available\n");
+                                goto err_desc_get;
+                        }
+
                         desc->lli.sar = reg;
                         desc->lli.dar = mem;
                         desc->lli.ctllo = ctllo | DWC_CTLL_DST_WIDTH(mem_width);
-                        desc->lli.ctlhi = len >> reg_width;
+                        if ((len >> reg_width) > DWC_MAX_COUNT) {
+                                dlen = DWC_MAX_COUNT << reg_width;
+                                mem += dlen;
+                                len -= dlen;
+                        } else {
+                                dlen = len;
+                                len = 0;
+                        }
+                        desc->lli.ctlhi = dlen >> reg_width;
 
                         if (!first) {
                                 first = desc;
@@ -772,7 +792,10 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                                                 &first->tx_list);
                         }
                         prev = desc;
-                        total_len += len;
+                        total_len += dlen;
+
+                        if (len)
+                                goto slave_sg_fromdev_fill_desc;
                 }
                 break;
         default: