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Subject[PATCH v4 7/7] dmaengine: xilinx_dma: Drop SG support for VDMA IP
Date
xilinx_vdma_start_transfer() is used only for VDMA IP, still it contains
conditional code on has_sg variable. has_sg is set only whenever the HW
does support SG mode, that is never true for VDMA IP.

This patch drops the never-taken branches.

Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
---
Changes in V4: introduced this patch in series
---
drivers/dma/xilinx/xilinx_dma.c | 84 +++++++++++++--------------------
1 file changed, 32 insertions(+), 52 deletions(-)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 78d0f2f8225e..07ceadef0a00 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -1093,6 +1093,8 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
struct xilinx_dma_tx_descriptor *desc, *tail_desc;
u32 reg, j;
struct xilinx_vdma_tx_segment *tail_segment;
+ struct xilinx_vdma_tx_segment *segment, *last = NULL;
+ int i = 0;

/* This function was invoked with lock held */
if (chan->err)
@@ -1112,14 +1114,6 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
tail_segment = list_last_entry(&tail_desc->segments,
struct xilinx_vdma_tx_segment, node);

- /*
- * If hardware is idle, then all descriptors on the running lists are
- * done, start new transfers
- */
- if (chan->has_sg)
- dma_ctrl_write(chan, XILINX_DMA_REG_CURDESC,
- desc->async_tx.phys);
-
/* Configure the hardware using info in the config structure */
reg = dma_ctrl_read(chan, XILINX_DMA_REG_DMACR);

@@ -1128,15 +1122,11 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
else
reg &= ~XILINX_DMA_DMACR_FRAMECNT_EN;

- /*
- * With SG, start with circular mode, so that BDs can be fetched.
- * In direct register mode, if not parking, enable circular mode
- */
- if (chan->has_sg || !config->park)
- reg |= XILINX_DMA_DMACR_CIRC_EN;
-
+ /* If not parking, enable circular mode */
if (config->park)
reg &= ~XILINX_DMA_DMACR_CIRC_EN;
+ else
+ reg |= XILINX_DMA_DMACR_CIRC_EN;

dma_ctrl_write(chan, XILINX_DMA_REG_DMACR, reg);

@@ -1158,48 +1148,38 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan)
return;

/* Start the transfer */
- if (chan->has_sg) {
- dma_ctrl_write(chan, XILINX_DMA_REG_TAILDESC,
- tail_segment->phys);
- list_splice_tail_init(&chan->pending_list, &chan->active_list);
- chan->desc_pendingcount = 0;
- } else {
- struct xilinx_vdma_tx_segment *segment, *last = NULL;
- int i = 0;
-
- if (chan->desc_submitcount < chan->num_frms)
- i = chan->desc_submitcount;
-
- list_for_each_entry(segment, &desc->segments, node) {
- if (chan->ext_addr)
- vdma_desc_write_64(chan,
- XILINX_VDMA_REG_START_ADDRESS_64(i++),
- segment->hw.buf_addr,
- segment->hw.buf_addr_msb);
- else
- vdma_desc_write(chan,
+ if (chan->desc_submitcount < chan->num_frms)
+ i = chan->desc_submitcount;
+
+ list_for_each_entry(segment, &desc->segments, node) {
+ if (chan->ext_addr)
+ vdma_desc_write_64(chan,
+ XILINX_VDMA_REG_START_ADDRESS_64(i++),
+ segment->hw.buf_addr,
+ segment->hw.buf_addr_msb);
+ else
+ vdma_desc_write(chan,
XILINX_VDMA_REG_START_ADDRESS(i++),
segment->hw.buf_addr);

- last = segment;
- }
-
- if (!last)
- return;
+ last = segment;
+ }

- /* HW expects these parameters to be same for one transaction */
- vdma_desc_write(chan, XILINX_DMA_REG_HSIZE, last->hw.hsize);
- vdma_desc_write(chan, XILINX_DMA_REG_FRMDLY_STRIDE,
- last->hw.stride);
- vdma_desc_write(chan, XILINX_DMA_REG_VSIZE, last->hw.vsize);
+ if (!last)
+ return;

- chan->desc_submitcount++;
- chan->desc_pendingcount--;
- list_del(&desc->node);
- list_add_tail(&desc->node, &chan->active_list);
- if (chan->desc_submitcount == chan->num_frms)
- chan->desc_submitcount = 0;
- }
+ /* HW expects these parameters to be same for one transaction */
+ vdma_desc_write(chan, XILINX_DMA_REG_HSIZE, last->hw.hsize);
+ vdma_desc_write(chan, XILINX_DMA_REG_FRMDLY_STRIDE,
+ last->hw.stride);
+ vdma_desc_write(chan, XILINX_DMA_REG_VSIZE, last->hw.vsize);
+
+ chan->desc_submitcount++;
+ chan->desc_pendingcount--;
+ list_del(&desc->node);
+ list_add_tail(&desc->node, &chan->active_list);
+ if (chan->desc_submitcount == chan->num_frms)
+ chan->desc_submitcount = 0;

chan->idle = false;
}
--
2.17.1
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