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

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