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dmaengine: xdmac: Add function to align width
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The code has some logic to compute the burst width according to the alignment
of the address we're using.

Move that in a function of its own to reduce code duplication.

Signed-off-by: Maxime Ripard <[email protected]>
Acked-by: Ludovic Desroches <[email protected]>
Signed-off-by: Vinod Koul <[email protected]>
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@mripard
mripard authored and Vinod Koul committed May 18, 2015
1 parent ee0fe35 commit f0816a3
Showing 1 changed file with 32 additions and 31 deletions.
63 changes: 32 additions & 31 deletions drivers/dma/at_xdmac.c
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Original file line number Diff line number Diff line change
Expand Up @@ -749,6 +749,35 @@ at_xdmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr,
return &first->tx_dma_desc;
}

static inline u32 at_xdmac_align_width(struct dma_chan *chan, dma_addr_t addr)
{
u32 width;

/*
* Check address alignment to select the greater data width we
* can use.
*
* Some XDMAC implementations don't provide dword transfer, in
* this case selecting dword has the same behavior as
* selecting word transfers.
*/
if (!(addr & 7)) {
width = AT_XDMAC_CC_DWIDTH_DWORD;
dev_dbg(chan2dev(chan), "%s: dwidth: double word\n", __func__);
} else if (!(addr & 3)) {
width = AT_XDMAC_CC_DWIDTH_WORD;
dev_dbg(chan2dev(chan), "%s: dwidth: word\n", __func__);
} else if (!(addr & 1)) {
width = AT_XDMAC_CC_DWIDTH_HALFWORD;
dev_dbg(chan2dev(chan), "%s: dwidth: half word\n", __func__);
} else {
width = AT_XDMAC_CC_DWIDTH_BYTE;
dev_dbg(chan2dev(chan), "%s: dwidth: byte\n", __func__);
}

return width;
}

static struct dma_async_tx_descriptor *
at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
size_t len, unsigned long flags)
Expand Down Expand Up @@ -779,24 +808,7 @@ at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
if (unlikely(!len))
return NULL;

/*
* Check address alignment to select the greater data width we can use.
* Some XDMAC implementations don't provide dword transfer, in this
* case selecting dword has the same behavior as selecting word transfers.
*/
if (!((src_addr | dst_addr) & 7)) {
dwidth = AT_XDMAC_CC_DWIDTH_DWORD;
dev_dbg(chan2dev(chan), "%s: dwidth: double word\n", __func__);
} else if (!((src_addr | dst_addr) & 3)) {
dwidth = AT_XDMAC_CC_DWIDTH_WORD;
dev_dbg(chan2dev(chan), "%s: dwidth: word\n", __func__);
} else if (!((src_addr | dst_addr) & 1)) {
dwidth = AT_XDMAC_CC_DWIDTH_HALFWORD;
dev_dbg(chan2dev(chan), "%s: dwidth: half word\n", __func__);
} else {
dwidth = AT_XDMAC_CC_DWIDTH_BYTE;
dev_dbg(chan2dev(chan), "%s: dwidth: byte\n", __func__);
}
dwidth = at_xdmac_align_width(chan, src_addr | dst_addr);

/* Prepare descriptors. */
while (remaining_size) {
Expand Down Expand Up @@ -826,19 +838,8 @@ at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
dev_dbg(chan2dev(chan), "%s: xfer_size=%zu\n", __func__, xfer_size);

/* Check remaining length and change data width if needed. */
if (!((src_addr | dst_addr | xfer_size) & 7)) {
dwidth = AT_XDMAC_CC_DWIDTH_DWORD;
dev_dbg(chan2dev(chan), "%s: dwidth: double word\n", __func__);
} else if (!((src_addr | dst_addr | xfer_size) & 3)) {
dwidth = AT_XDMAC_CC_DWIDTH_WORD;
dev_dbg(chan2dev(chan), "%s: dwidth: word\n", __func__);
} else if (!((src_addr | dst_addr | xfer_size) & 1)) {
dwidth = AT_XDMAC_CC_DWIDTH_HALFWORD;
dev_dbg(chan2dev(chan), "%s: dwidth: half word\n", __func__);
} else if ((src_addr | dst_addr | xfer_size) & 1) {
dwidth = AT_XDMAC_CC_DWIDTH_BYTE;
dev_dbg(chan2dev(chan), "%s: dwidth: byte\n", __func__);
}
dwidth = at_xdmac_align_width(chan,
src_addr | dst_addr | xfer_size);
chan_cc |= AT_XDMAC_CC_DWIDTH(dwidth);

ublen = xfer_size >> dwidth;
Expand Down

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