| Message ID | 23394379.8nZhno5foU@bear (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
On Tue, Mar 06, 2018 at 11:03:22AM -0500, Frank Mori Hess wrote: > Do DMAFLUSHP _before_ the first DMAWFP to ensure controller > and peripheral are in agreement about dma request state before first > transfer. Add support for burst transfers to/from peripherals. In the new > scheme, the controller does as many burst transfers as it can then > transfers the remaining dregs with either single transfers for > peripherals, or with a reduced size burst for memory-to-memory transfers. > > Signed-off-by: Frank Mori Hess <fmh6jj@gmail.com> > Tested-by: Frank Mori Hess <fmh6jj@gmail.com> sorry if it wasnt clear earlier, the lines below should come after the --- line. git-am skips that part while applying.. > > I tested dma transfers to peripherals with designware serial port > (drivers/tty/serial/8250/8250_dw.c) and a GPIB interface > (https://github.com/fmhess/fmh_gpib_core). I tested memory-to-memory > transfers using the dmatest module. > > v3 of this patch should be the same as v2 except with checkpatch.pl > warnings and errors cleaned up. > > --- > drivers/dma/pl330.c | 146 +++++++++++++++++++++++++++++++++++++--------------- > 1 file changed, 104 insertions(+), 42 deletions(-) > > diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c > index d7327fd5f445..cc2e4456bec1 100644 > --- a/drivers/dma/pl330.c > +++ b/drivers/dma/pl330.c > @@ -1094,26 +1094,33 @@ static inline int _ldst_memtomem(unsigned dry_run, u8 buf[], > return off; > } > > -static inline int _ldst_devtomem(struct pl330_dmac *pl330, unsigned dry_run, > - u8 buf[], const struct _xfer_spec *pxs, > - int cyc) > +static inline int _ldst_devtomem(struct pl330_dmac *pl330, > + unsigned int dry_run, u8 buf[], > + const struct _xfer_spec *pxs, > + int cyc, enum pl330_cond cond) > { > int off = 0; > - enum pl330_cond cond; > > if (pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) > cond = BURST; > - else > - cond = SINGLE; > > + /* do FLUSHP at beginning to clear any stale dma requests before the > + * first WFP. > + */ multiline comments should be: /* * this is an example of multi-line * comment */ Pls fix at this and other places... > static inline int _ldst_memtodev(struct pl330_dmac *pl330, > unsigned dry_run, u8 buf[], > - const struct _xfer_spec *pxs, int cyc) > + const struct _xfer_spec *pxs, int cyc, > + enum pl330_cond cond) > { > int off = 0; > - enum pl330_cond cond; > > if (pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) > cond = BURST; > - else > - cond = SINGLE; > > + /* do FLUSHP at beginning to clear any stale dma requests before the > + * first WFP. > + */ > + if (!(pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)) > + off += _emit_FLUSHP(dry_run, &buf[off], pxs->desc->peri); > while (cyc--) { > off += _emit_WFP(dry_run, &buf[off], cond, pxs->desc->peri); > off += _emit_LD(dry_run, &buf[off], ALWAYS); > - off += _emit_STP(dry_run, &buf[off], cond, pxs->desc->peri); > - > - if (!(pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)) > - off += _emit_FLUSHP(dry_run, &buf[off], > - pxs->desc->peri); > + if (cond == ALWAYS) { > + off += _emit_STP(dry_run, &buf[off], SINGLE, > + pxs->desc->peri); > + off += _emit_STP(dry_run, &buf[off], BURST, > + pxs->desc->peri); > + } else { > + off += _emit_STP(dry_run, &buf[off], cond, > + pxs->desc->peri); > + } this looks quite similar to previous routine above, if so can we please make it common function and invoke from both of these... > +static int _dregs(struct pl330_dmac *pl330, unsigned int dry_run, u8 buf[], > + const struct _xfer_spec *pxs, int transfer_length) > +{ > + int off = 0; > + int dregs_ccr; > + > + if (transfer_length == 0) > + return off; > + > + switch (pxs->desc->rqtype) { > + case DMA_MEM_TO_DEV: > + off += _ldst_memtodev(pl330, dry_run, &buf[off], pxs, > + transfer_length, SINGLE); > + break; empty line after each case pls > + case DMA_DEV_TO_MEM: > + off += _ldst_devtomem(pl330, dry_run, &buf[off], pxs, > + transfer_length, SINGLE); > + break; > + case DMA_MEM_TO_MEM: > + dregs_ccr = pxs->ccr; > + dregs_ccr &= ~((0xf << CC_SRCBRSTLEN_SHFT) | > + (0xf << CC_DSTBRSTLEN_SHFT)); > + dregs_ccr |= (((transfer_length - 1) & 0xf) << > + CC_SRCBRSTLEN_SHFT); > + dregs_ccr |= (((transfer_length - 1) & 0xf) << > + CC_DSTBRSTLEN_SHFT); > + off += _emit_MOV(dry_run, &buf[off], CCR, dregs_ccr); > + off += _ldst_memtomem(dry_run, &buf[off], pxs, 1); > + break; > + default: > + off += 0x40000000; /* Scare off the Client */ Can you explain this bit, shouldnt this be err? > @@ -1303,11 +1362,6 @@ static int _setup_req(struct pl330_dmac *pl330, unsigned dry_run, > /* DMAMOV CCR, ccr */ > off += _emit_MOV(dry_run, &buf[off], CCR, pxs->ccr); > > - x = &pxs->desc->px; > - /* Error if xfer length is not aligned at burst size */ > - if (x->bytes % (BRST_SIZE(pxs->ccr) * BRST_LEN(pxs->ccr))) > - return -EINVAL; > - > off += _setup_xfer(pl330, dry_run, &buf[off], pxs); > > /* DMASEV peripheral/event */ > @@ -2115,15 +2169,29 @@ static int pl330_config(struct dma_chan *chan, > pch->fifo_addr = slave_config->dst_addr; > if (slave_config->dst_addr_width) > pch->burst_sz = __ffs(slave_config->dst_addr_width); > - if (slave_config->dst_maxburst) > - pch->burst_len = slave_config->dst_maxburst; > + if (pch->dmac->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) > + pch->burst_len = 1; so in this case we don't honour the requested burst length? > + else if (slave_config->dst_maxburst) { > + if (slave_config->dst_maxburst > PL330_MAX_BURST) > + pch->burst_len = PL330_MAX_BURST; > + else > + pch->burst_len = slave_config->dst_maxburst; > + } else > + pch->burst_len = 1; > } else if (slave_config->direction == DMA_DEV_TO_MEM) { > if (slave_config->src_addr) > pch->fifo_addr = slave_config->src_addr; > if (slave_config->src_addr_width) > pch->burst_sz = __ffs(slave_config->src_addr_width); > - if (slave_config->src_maxburst) > - pch->burst_len = slave_config->src_maxburst; > + if (pch->dmac->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) > + pch->burst_len = 1; > + else if (slave_config->src_maxburst) { > + if (slave_config->src_maxburst > PL330_MAX_BURST) > + pch->burst_len = PL330_MAX_BURST; > + else > + pch->burst_len = slave_config->src_maxburst; > + } else > + pch->burst_len = 1; again this looks duplicate..
On Sun, Mar 11, 2018 at 11:01 AM, Vinod Koul <vinod.koul@intel.com> wrote: > > sorry if it wasnt clear earlier, the lines below should come after the --- > line. git-am skips that part while applying.. ok >> >> + /* do FLUSHP at beginning to clear any stale dma requests before the >> + * first WFP. >> + */ > > multiline comments should be: > > /* > * this is an example of multi-line > * comment > */ > > Pls fix at this and other places... ok > >> static inline int _ldst_memtodev(struct pl330_dmac *pl330, >> unsigned dry_run, u8 buf[], >> - const struct _xfer_spec *pxs, int cyc) >> + const struct _xfer_spec *pxs, int cyc, >> + enum pl330_cond cond) >> { >> int off = 0; >> - enum pl330_cond cond; >> >> if (pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) >> cond = BURST; >> - else >> - cond = SINGLE; >> >> + /* do FLUSHP at beginning to clear any stale dma requests before the >> + * first WFP. >> + */ >> + if (!(pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)) >> + off += _emit_FLUSHP(dry_run, &buf[off], pxs->desc->peri); >> while (cyc--) { >> off += _emit_WFP(dry_run, &buf[off], cond, pxs->desc->peri); >> off += _emit_LD(dry_run, &buf[off], ALWAYS); >> - off += _emit_STP(dry_run, &buf[off], cond, pxs->desc->peri); >> - >> - if (!(pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)) >> - off += _emit_FLUSHP(dry_run, &buf[off], >> - pxs->desc->peri); >> + if (cond == ALWAYS) { >> + off += _emit_STP(dry_run, &buf[off], SINGLE, >> + pxs->desc->peri); >> + off += _emit_STP(dry_run, &buf[off], BURST, >> + pxs->desc->peri); >> + } else { >> + off += _emit_STP(dry_run, &buf[off], cond, >> + pxs->desc->peri); >> + } > > this looks quite similar to previous routine above, if so can we please make > it common function and invoke from both of these... _ldst_memtodev and _ldst_devtomem are similar, but they were even more similar before my patch. Do I really have to refactor existing code to get my patch applied? I'm not trying to take over maintainership of the pl330.c driver. > >> +static int _dregs(struct pl330_dmac *pl330, unsigned int dry_run, u8 buf[], >> + const struct _xfer_spec *pxs, int transfer_length) >> +{ >> + int off = 0; >> + int dregs_ccr; >> + >> + if (transfer_length == 0) >> + return off; >> + >> + switch (pxs->desc->rqtype) { >> + case DMA_MEM_TO_DEV: >> + off += _ldst_memtodev(pl330, dry_run, &buf[off], pxs, >> + transfer_length, SINGLE); >> + break; > > empty line after each case pls ok > >> + case DMA_DEV_TO_MEM: >> + off += _ldst_devtomem(pl330, dry_run, &buf[off], pxs, >> + transfer_length, SINGLE); >> + break; >> + case DMA_MEM_TO_MEM: >> + dregs_ccr = pxs->ccr; >> + dregs_ccr &= ~((0xf << CC_SRCBRSTLEN_SHFT) | >> + (0xf << CC_DSTBRSTLEN_SHFT)); >> + dregs_ccr |= (((transfer_length - 1) & 0xf) << >> + CC_SRCBRSTLEN_SHFT); >> + dregs_ccr |= (((transfer_length - 1) & 0xf) << >> + CC_DSTBRSTLEN_SHFT); >> + off += _emit_MOV(dry_run, &buf[off], CCR, dregs_ccr); >> + off += _ldst_memtomem(dry_run, &buf[off], pxs, 1); >> + break; >> + default: >> + off += 0x40000000; /* Scare off the Client */ > > Can you explain this bit, shouldnt this be err? > I just copied that behavior from the existing _bursts() function. I guess the original author's idea was returning a big offset would result in a dry run failure due to exceeding the maximum buffer size. I do agree an error would be better, although it would require refactoring since the return values from _bursts and _dregs are not checked for errors, they just blindly add the return value to the offset. >> @@ -1303,11 +1362,6 @@ static int _setup_req(struct pl330_dmac *pl330, unsigned dry_run, >> /* DMAMOV CCR, ccr */ >> off += _emit_MOV(dry_run, &buf[off], CCR, pxs->ccr); >> >> - x = &pxs->desc->px; >> - /* Error if xfer length is not aligned at burst size */ >> - if (x->bytes % (BRST_SIZE(pxs->ccr) * BRST_LEN(pxs->ccr))) >> - return -EINVAL; >> - >> off += _setup_xfer(pl330, dry_run, &buf[off], pxs); >> >> /* DMASEV peripheral/event */ >> @@ -2115,15 +2169,29 @@ static int pl330_config(struct dma_chan *chan, >> pch->fifo_addr = slave_config->dst_addr; >> if (slave_config->dst_addr_width) >> pch->burst_sz = __ffs(slave_config->dst_addr_width); >> - if (slave_config->dst_maxburst) >> - pch->burst_len = slave_config->dst_maxburst; >> + if (pch->dmac->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) >> + pch->burst_len = 1; > > so in this case we don't honour the requested burst length? > I don't have any experience with the PL330_QUIRK_BROKEN_NO_FLUSHP hardware, or knowledge of how it (mis)behaves. So I just tried to maintain the existing behavior as much as possible. The old code advertised the max burst length as 1 with PL330_QUIRK_BROKEN_NO_FLUSHP hardware, and programmed the pl330 to respond only to burst requests (and of course the old code never did any peripheral bursts longer than 1). I actually don't mind changing the behavior of PL330_QUIRK_BROKEN_NO_FLUSHP but it seems like someone with more knowledge of that hardware should be involved, like the rock-chips.com guys who introduced it in commit 271e1b86e69140fe65718ae8a264284c46d3129d , >> + else if (slave_config->dst_maxburst) { >> + if (slave_config->dst_maxburst > PL330_MAX_BURST) >> + pch->burst_len = PL330_MAX_BURST; >> + else >> + pch->burst_len = slave_config->dst_maxburst; >> + } else >> + pch->burst_len = 1; >> } else if (slave_config->direction == DMA_DEV_TO_MEM) { >> if (slave_config->src_addr) >> pch->fifo_addr = slave_config->src_addr; >> if (slave_config->src_addr_width) >> pch->burst_sz = __ffs(slave_config->src_addr_width); >> - if (slave_config->src_maxburst) >> - pch->burst_len = slave_config->src_maxburst; >> + if (pch->dmac->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) >> + pch->burst_len = 1; >> + else if (slave_config->src_maxburst) { >> + if (slave_config->src_maxburst > PL330_MAX_BURST) >> + pch->burst_len = PL330_MAX_BURST; >> + else >> + pch->burst_len = slave_config->src_maxburst; >> + } else >> + pch->burst_len = 1; > > again this looks duplicate.. > -- > ~Vinod Ok, I'll make a little helper function.
diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index d7327fd5f445..cc2e4456bec1 100644 --- a/drivers/dma/pl330.c +++ b/drivers/dma/pl330.c @@ -1094,26 +1094,33 @@ static inline int _ldst_memtomem(unsigned dry_run, u8 buf[], return off; } -static inline int _ldst_devtomem(struct pl330_dmac *pl330, unsigned dry_run, - u8 buf[], const struct _xfer_spec *pxs, - int cyc) +static inline int _ldst_devtomem(struct pl330_dmac *pl330, + unsigned int dry_run, u8 buf[], + const struct _xfer_spec *pxs, + int cyc, enum pl330_cond cond) { int off = 0; - enum pl330_cond cond; if (pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) cond = BURST; - else - cond = SINGLE; + /* do FLUSHP at beginning to clear any stale dma requests before the + * first WFP. + */ + if (!(pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)) + off += _emit_FLUSHP(dry_run, &buf[off], pxs->desc->peri); while (cyc--) { off += _emit_WFP(dry_run, &buf[off], cond, pxs->desc->peri); - off += _emit_LDP(dry_run, &buf[off], cond, pxs->desc->peri); + if (cond == ALWAYS) { + off += _emit_LDP(dry_run, &buf[off], SINGLE, + pxs->desc->peri); + off += _emit_LDP(dry_run, &buf[off], BURST, + pxs->desc->peri); + } else { + off += _emit_LDP(dry_run, &buf[off], cond, + pxs->desc->peri); + } off += _emit_ST(dry_run, &buf[off], ALWAYS); - - if (!(pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)) - off += _emit_FLUSHP(dry_run, &buf[off], - pxs->desc->peri); } return off; @@ -1121,24 +1128,31 @@ static inline int _ldst_devtomem(struct pl330_dmac *pl330, unsigned dry_run, static inline int _ldst_memtodev(struct pl330_dmac *pl330, unsigned dry_run, u8 buf[], - const struct _xfer_spec *pxs, int cyc) + const struct _xfer_spec *pxs, int cyc, + enum pl330_cond cond) { int off = 0; - enum pl330_cond cond; if (pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) cond = BURST; - else - cond = SINGLE; + /* do FLUSHP at beginning to clear any stale dma requests before the + * first WFP. + */ + if (!(pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)) + off += _emit_FLUSHP(dry_run, &buf[off], pxs->desc->peri); while (cyc--) { off += _emit_WFP(dry_run, &buf[off], cond, pxs->desc->peri); off += _emit_LD(dry_run, &buf[off], ALWAYS); - off += _emit_STP(dry_run, &buf[off], cond, pxs->desc->peri); - - if (!(pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)) - off += _emit_FLUSHP(dry_run, &buf[off], - pxs->desc->peri); + if (cond == ALWAYS) { + off += _emit_STP(dry_run, &buf[off], SINGLE, + pxs->desc->peri); + off += _emit_STP(dry_run, &buf[off], BURST, + pxs->desc->peri); + } else { + off += _emit_STP(dry_run, &buf[off], cond, + pxs->desc->peri); + } } return off; @@ -1148,13 +1162,16 @@ static int _bursts(struct pl330_dmac *pl330, unsigned dry_run, u8 buf[], const struct _xfer_spec *pxs, int cyc) { int off = 0; + enum pl330_cond cond = BRST_LEN(pxs->ccr) > 1 ? BURST : SINGLE; switch (pxs->desc->rqtype) { case DMA_MEM_TO_DEV: - off += _ldst_memtodev(pl330, dry_run, &buf[off], pxs, cyc); + off += _ldst_memtodev(pl330, dry_run, &buf[off], pxs, cyc, + cond); break; case DMA_DEV_TO_MEM: - off += _ldst_devtomem(pl330, dry_run, &buf[off], pxs, cyc); + off += _ldst_devtomem(pl330, dry_run, &buf[off], pxs, cyc, + cond); break; case DMA_MEM_TO_MEM: off += _ldst_memtomem(dry_run, &buf[off], pxs, cyc); @@ -1167,6 +1184,46 @@ static int _bursts(struct pl330_dmac *pl330, unsigned dry_run, u8 buf[], return off; } +/* transfer dregs with single transfers to peripheral, or a reduced size burst + * for mem-to-mem. + */ +static int _dregs(struct pl330_dmac *pl330, unsigned int dry_run, u8 buf[], + const struct _xfer_spec *pxs, int transfer_length) +{ + int off = 0; + int dregs_ccr; + + if (transfer_length == 0) + return off; + + switch (pxs->desc->rqtype) { + case DMA_MEM_TO_DEV: + off += _ldst_memtodev(pl330, dry_run, &buf[off], pxs, + transfer_length, SINGLE); + break; + case DMA_DEV_TO_MEM: + off += _ldst_devtomem(pl330, dry_run, &buf[off], pxs, + transfer_length, SINGLE); + break; + case DMA_MEM_TO_MEM: + dregs_ccr = pxs->ccr; + dregs_ccr &= ~((0xf << CC_SRCBRSTLEN_SHFT) | + (0xf << CC_DSTBRSTLEN_SHFT)); + dregs_ccr |= (((transfer_length - 1) & 0xf) << + CC_SRCBRSTLEN_SHFT); + dregs_ccr |= (((transfer_length - 1) & 0xf) << + CC_DSTBRSTLEN_SHFT); + off += _emit_MOV(dry_run, &buf[off], CCR, dregs_ccr); + off += _ldst_memtomem(dry_run, &buf[off], pxs, 1); + break; + default: + off += 0x40000000; /* Scare off the Client */ + break; + } + + return off; +} + /* Returns bytes consumed and updates bursts */ static inline int _loop(struct pl330_dmac *pl330, unsigned dry_run, u8 buf[], unsigned long *bursts, const struct _xfer_spec *pxs) @@ -1256,6 +1313,8 @@ static inline int _setup_loops(struct pl330_dmac *pl330, struct pl330_xfer *x = &pxs->desc->px; u32 ccr = pxs->ccr; unsigned long c, bursts = BYTE_TO_BURST(x->bytes, ccr); + int num_dregs = (x->bytes - BURST_TO_BYTE(bursts, ccr)) / + BRST_SIZE(ccr); int off = 0; while (bursts) { @@ -1263,6 +1322,7 @@ static inline int _setup_loops(struct pl330_dmac *pl330, off += _loop(pl330, dry_run, &buf[off], &c, pxs); bursts -= c; } + off += _dregs(pl330, dry_run, &buf[off], pxs, num_dregs); return off; } @@ -1294,7 +1354,6 @@ static int _setup_req(struct pl330_dmac *pl330, unsigned dry_run, struct _xfer_spec *pxs) { struct _pl330_req *req = &thrd->req[index]; - struct pl330_xfer *x; u8 *buf = req->mc_cpu; int off = 0; @@ -1303,11 +1362,6 @@ static int _setup_req(struct pl330_dmac *pl330, unsigned dry_run, /* DMAMOV CCR, ccr */ off += _emit_MOV(dry_run, &buf[off], CCR, pxs->ccr); - x = &pxs->desc->px; - /* Error if xfer length is not aligned at burst size */ - if (x->bytes % (BRST_SIZE(pxs->ccr) * BRST_LEN(pxs->ccr))) - return -EINVAL; - off += _setup_xfer(pl330, dry_run, &buf[off], pxs); /* DMASEV peripheral/event */ @@ -2115,15 +2169,29 @@ static int pl330_config(struct dma_chan *chan, pch->fifo_addr = slave_config->dst_addr; if (slave_config->dst_addr_width) pch->burst_sz = __ffs(slave_config->dst_addr_width); - if (slave_config->dst_maxburst) - pch->burst_len = slave_config->dst_maxburst; + if (pch->dmac->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) + pch->burst_len = 1; + else if (slave_config->dst_maxburst) { + if (slave_config->dst_maxburst > PL330_MAX_BURST) + pch->burst_len = PL330_MAX_BURST; + else + pch->burst_len = slave_config->dst_maxburst; + } else + pch->burst_len = 1; } else if (slave_config->direction == DMA_DEV_TO_MEM) { if (slave_config->src_addr) pch->fifo_addr = slave_config->src_addr; if (slave_config->src_addr_width) pch->burst_sz = __ffs(slave_config->src_addr_width); - if (slave_config->src_maxburst) - pch->burst_len = slave_config->src_maxburst; + if (pch->dmac->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) + pch->burst_len = 1; + else if (slave_config->src_maxburst) { + if (slave_config->src_maxburst > PL330_MAX_BURST) + pch->burst_len = PL330_MAX_BURST; + else + pch->burst_len = slave_config->src_maxburst; + } else + pch->burst_len = 1; } return 0; @@ -2517,14 +2585,8 @@ static inline int get_burst_len(struct dma_pl330_desc *desc, size_t len) burst_len >>= desc->rqcfg.brst_size; /* src/dst_burst_len can't be more than 16 */ - if (burst_len > 16) - burst_len = 16; - - while (burst_len > 1) { - if (!(len % (burst_len << desc->rqcfg.brst_size))) - break; - burst_len--; - } + if (burst_len > PL330_MAX_BURST) + burst_len = PL330_MAX_BURST; return burst_len; } @@ -2596,7 +2658,7 @@ static struct dma_async_tx_descriptor *pl330_prep_dma_cyclic( desc->rqtype = direction; desc->rqcfg.brst_size = pch->burst_sz; - desc->rqcfg.brst_len = 1; + desc->rqcfg.brst_len = pch->burst_len; desc->bytes_requested = period_len; fill_px(&desc->px, dst, src, period_len); @@ -2741,7 +2803,7 @@ pl330_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, } desc->rqcfg.brst_size = pch->burst_sz; - desc->rqcfg.brst_len = 1; + desc->rqcfg.brst_len = pch->burst_len; desc->rqtype = direction; desc->bytes_requested = sg_dma_len(sg); }