[PATCH v3] dmaengine: pl330: flush before wait, and add dev burst support.

[PATCH v3] dmaengine: pl330: flush before wait, and add dev burst support.

[Frank Mori Hess]

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>

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.
+	 */
+	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);
 	}
-- 
2.11.0

Re: [PATCH v3] dmaengine: pl330: flush before wait, and add dev burst support.

[Vinod Koul]

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..
-- 
~Vinod

Re: [PATCH v3] dmaengine: pl330: flush before wait, and add dev burst support.

[Frank Mori Hess]

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.

-- 
Frank

[PATCH v4] dmaengine: pl330: flush before wait, and add dev burst support.

[Frank Mori Hess]

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>
---

I tested dma transfers to peripherals with v3 patch and 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.

v4 addresses cosmetic complaints about v3, should be functionally unchanged.

 drivers/dma/pl330.c | 209 +++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 159 insertions(+), 50 deletions(-)

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index d7327fd5f445..819a578e317f 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -27,6 +27,7 @@
 #include <linux/of_dma.h>
 #include <linux/err.h>
 #include <linux/pm_runtime.h>
+#include <linux/bug.h>
 
 #include "dmaengine.h"
 #define PL330_MAX_CHAN		8
@@ -1094,51 +1095,96 @@ 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 u32 _emit_load(unsigned int dry_run, u8 buf[],
+	enum pl330_cond cond, enum dma_transfer_direction direction,
+	u8 peri)
 {
 	int off = 0;
-	enum pl330_cond cond;
 
-	if (pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)
-		cond = BURST;
-	else
-		cond = SINGLE;
+	switch (direction) {
+	case DMA_MEM_TO_MEM:
+		/* fall through */
+	case DMA_MEM_TO_DEV:
+		off += _emit_LD(dry_run, &buf[off], cond);
+		break;
 
-	while (cyc--) {
-		off += _emit_WFP(dry_run, &buf[off], cond, pxs->desc->peri);
-		off += _emit_LDP(dry_run, &buf[off], cond, pxs->desc->peri);
-		off += _emit_ST(dry_run, &buf[off], ALWAYS);
+	case DMA_DEV_TO_MEM:
+		if (cond == ALWAYS) {
+			off += _emit_LDP(dry_run, &buf[off], SINGLE,
+				peri);
+			off += _emit_LDP(dry_run, &buf[off], BURST,
+				peri);
+		} else {
+			off += _emit_LDP(dry_run, &buf[off], cond,
+				peri);
+		}
+		break;
 
-		if (!(pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP))
-			off += _emit_FLUSHP(dry_run, &buf[off],
-					    pxs->desc->peri);
+	default:
+		/* this code should be unreachable */
+		WARN_ON(1);
+		break;
 	}
 
 	return off;
 }
 
-static inline int _ldst_memtodev(struct pl330_dmac *pl330,
+static inline u32 _emit_store(unsigned int dry_run, u8 buf[],
+	enum pl330_cond cond, enum dma_transfer_direction direction,
+	u8 peri)
+{
+	int off = 0;
+
+	switch (direction) {
+	case DMA_MEM_TO_MEM:
+		/* fall through */
+	case DMA_DEV_TO_MEM:
+		off += _emit_ST(dry_run, &buf[off], cond);
+		break;
+
+	case DMA_MEM_TO_DEV:
+		if (cond == ALWAYS) {
+			off += _emit_STP(dry_run, &buf[off], SINGLE,
+				peri);
+			off += _emit_STP(dry_run, &buf[off], BURST,
+				peri);
+		} else {
+			off += _emit_STP(dry_run, &buf[off], cond,
+				peri);
+		}
+		break;
+
+	default:
+		/* this code should be unreachable */
+		WARN_ON(1);
+		break;
+	}
+
+	return off;
+}
+
+static inline int _ldst_peripheral(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);
+		off += _emit_load(dry_run, &buf[off], cond, pxs->desc->rqtype,
+			pxs->desc->peri);
+		off += _emit_store(dry_run, &buf[off], cond, pxs->desc->rqtype,
+			pxs->desc->peri);
 	}
 
 	return off;
@@ -1148,19 +1194,65 @@ 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);
-		break;
+		/* fall through */
 	case DMA_DEV_TO_MEM:
-		off += _ldst_devtomem(pl330, dry_run, &buf[off], pxs, cyc);
+		off += _ldst_peripheral(pl330, dry_run, &buf[off], pxs, cyc,
+			cond);
 		break;
+
 	case DMA_MEM_TO_MEM:
 		off += _ldst_memtomem(dry_run, &buf[off], pxs, cyc);
 		break;
+
+	default:
+		/* this code should be unreachable */
+		WARN_ON(1);
+		break;
+	}
+
+	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:
+		/* fall through */
+	case DMA_DEV_TO_MEM:
+		off += _ldst_peripheral(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 */
+		/* this code should be unreachable */
+		WARN_ON(1);
 		break;
 	}
 
@@ -1256,6 +1348,8 @@ 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 +1357,7 @@ 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 +1389,6 @@ 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 +1397,6 @@ 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 */
@@ -1365,6 +1454,20 @@ static int pl330_submit_req(struct pl330_thread *thrd,
 	u32 ccr;
 	int ret = 0;
 
+	switch (desc->rqtype) {
+	case DMA_MEM_TO_DEV:
+		break;
+
+	case DMA_DEV_TO_MEM:
+		break;
+
+	case DMA_MEM_TO_MEM:
+		break;
+
+	default:
+		return -ENOTSUPP;
+	}
+
 	if (pl330->state == DYING
 		|| pl330->dmac_tbd.reset_chan & (1 << thrd->id)) {
 		dev_info(thrd->dmac->ddma.dev, "%s:%d\n",
@@ -2104,6 +2207,18 @@ static bool pl330_prep_slave_fifo(struct dma_pl330_chan *pch,
 	return true;
 }
 
+static int fixup_burst_len(int max_burst_len, int quirks)
+{
+	if (quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)
+		return 1;
+	else if (max_burst_len > PL330_MAX_BURST)
+		return PL330_MAX_BURST;
+	else if (max_burst_len < 1)
+		return 1;
+	else
+		return max_burst_len;
+}
+
 static int pl330_config(struct dma_chan *chan,
 			struct dma_slave_config *slave_config)
 {
@@ -2115,15 +2230,15 @@ 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;
+		pch->burst_len = fixup_burst_len(slave_config->dst_maxburst,
+			pch->dmac->quirks);
 	} 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;
+		pch->burst_len = fixup_burst_len(slave_config->src_maxburst,
+			pch->dmac->quirks);
 	}
 
 	return 0;
@@ -2517,14 +2632,8 @@ 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 +2705,7 @@ 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 +2850,7 @@ 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);
 	}
-- 
2.11.0

Re: [PATCH v4] dmaengine: pl330: flush before wait, and add dev burst support.

[Frank Mori Hess]

On Tue, Mar 13, 2018 at 2:34 PM, Frank Mori Hess <fmh6jj@gmail.com> 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.

Hi, what is the state of this patch?  I just noticed in patchwork it
is now listed as "Not applicable"?  The original broken-by-wordwrap
patch is listed as "Accepted"?

https://patchwork.kernel.org/project/linux-dmaengine/list/?submitter=178687&state=*

I found it has a bug handling dregs btw, I'll include a fix for that
in the next version or as a follow-on patch as appropriate.

Re: [PATCH v4] dmaengine: pl330: flush before wait, and add dev burst support.

[Vinod Koul]

On Mon, Apr 09, 2018 at 08:41:18PM -0400, Frank Mori Hess wrote:
> On Tue, Mar 13, 2018 at 2:34 PM, Frank Mori Hess <fmh6jj@gmail.com> 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.
> 
> Hi, what is the state of this patch?  I just noticed in patchwork it
> is now listed as "Not applicable"?  The original broken-by-wordwrap
> patch is listed as "Accepted"?
> 
> https://patchwork.kernel.org/project/linux-dmaengine/list/?submitter=178687&state=*

That is not correct state, my script would update as not applicable when it
doesn't find patch in my queue..

> I found it has a bug handling dregs btw, I'll include a fix for that
> in the next version or as a follow-on patch as appropriate.

Looks like I have missed this one somehow, so please update the patch with
fix and I shall look into it.

Thanks

-- 
~Vinod

Re: [PATCH v4] dmaengine: pl330: flush before wait, and add dev burst support.

[Frank Mori Hess]

On Tue, Apr 10, 2018 at 11:37 AM, Vinod Koul <vinod.koul@intel.com> wrote:
>>
>> Hi, what is the state of this patch?  I just noticed in patchwork it
>> is now listed as "Not applicable"?  The original broken-by-wordwrap
>> patch is listed as "Accepted"?
>>
>> https://patchwork.kernel.org/project/linux-dmaengine/list/?submitter=178687&state=*
>
> That is not correct state, my script would update as not applicable when it
> doesn't find patch in my queue..
>
>> I found it has a bug handling dregs btw, I'll include a fix for that
>> in the next version or as a follow-on patch as appropriate.
>
> Looks like I have missed this one somehow, so please update the patch with
> fix and I shall look into it.
>

Ok, I tested the v4 patch and it turns out it was a false alarm about
the bug in handling dregs.  It works fine.  I've registered in the
dmaengine patchwork, and changed the state of the v4 patch back to
"new".



-- 
Frank

Re: [PATCH v4] dmaengine: pl330: flush before wait, and add dev burst support.

[Vinod Koul]

On Sun, Apr 15, 2018 at 02:12:30PM -0400, Frank Mori Hess wrote:
> On Tue, Apr 10, 2018 at 11:37 AM, Vinod Koul <vinod.koul@intel.com> wrote:
> >>
> >> Hi, what is the state of this patch?  I just noticed in patchwork it
> >> is now listed as "Not applicable"?  The original broken-by-wordwrap
> >> patch is listed as "Accepted"?
> >>
> >> https://patchwork.kernel.org/project/linux-dmaengine/list/?submitter=178687&state=*
> >
> > That is not correct state, my script would update as not applicable when it
> > doesn't find patch in my queue..
> >
> >> I found it has a bug handling dregs btw, I'll include a fix for that
> >> in the next version or as a follow-on patch as appropriate.
> >
> > Looks like I have missed this one somehow, so please update the patch with
> > fix and I shall look into it.
> >
> 
> Ok, I tested the v4 patch and it turns out it was a false alarm about
> the bug in handling dregs.  It works fine.  I've registered in the
> dmaengine patchwork, and changed the state of the v4 patch back to
> "new".

Can you please repost this one after rebasing to dmaengine -next

-- 
~Vinod