Re: [PATCH v2 01/13] dmaengine: pl330: Remove the burst limit for quirk 'NO-FLUSHP'

[sugar zhang <sugar.zhang@xxxxxxxxxxxxxx>]

On 2020/6/24 15:54, Vinod Koul wrote:
> On 09-06-20, 09:14, Sugar Zhang wrote:
> > There is no reason to limit the performance on the 'NO-FLUSHP' SoCs,
> > cuz these platforms are just that the 'FLUSHP' instruction is broken.
> Lets not use terms like cuz... 'because' is perfect term :)
>
> It can rephrased to:
> There is no reason to limit the performance on the 'NO-FLUSHP' SoCs
> beacuse 'FLUSHP' instruction is broken on these platforms, so remove the
> limit to improve the efficiency
Thanks, I will send a v3 including these.
> > so, remove the limit to improve the efficiency.
> >
> > Signed-off-by: Sugar Zhang <sugar.zhang@xxxxxxxxxxxxxx>
> > ---
> >
> > Changes in v2: None
> >
> >   drivers/dma/pl330.c | 34 ++++++++++++++++++++++------------
> >   1 file changed, 22 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
> > index 6a158ee..ff0a91f 100644
> > --- a/drivers/dma/pl330.c
> > +++ b/drivers/dma/pl330.c
> > @@ -1183,9 +1183,6 @@ static inline int _ldst_peripheral(struct pl330_dmac *pl330,
> >   {
> >   	int off = 0;
> >   
> > -	if (pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP)
> > -		cond = BURST;
> > -
> >   	/*
> >   	 * do FLUSHP at beginning to clear any stale dma requests before the
> >   	 * first WFP.
> > @@ -1231,8 +1228,9 @@ static int _bursts(struct pl330_dmac *pl330, unsigned dry_run, u8 buf[],
> >   }
> >   
> >   /*
> > - * transfer dregs with single transfers to peripheral, or a reduced size burst
> > - * for mem-to-mem.
> > + * only the unaligned bursts transfers have the dregs.
> > + * transfer dregs with a reduced size burst to peripheral,
> > + * or a reduced size burst for mem-to-mem.
> This is not related to broken flush and should be a different patch
> explaining why this changes were done
ok, I will split this patch in v3.
> >    */
> >   static int _dregs(struct pl330_dmac *pl330, unsigned int dry_run, u8 buf[],
> >   		const struct _xfer_spec *pxs, int transfer_length)
> > @@ -1247,8 +1245,23 @@ static int _dregs(struct pl330_dmac *pl330, unsigned int dry_run, u8 buf[],
> >   	case DMA_MEM_TO_DEV:
> >   		/* fall through */
> >   	case DMA_DEV_TO_MEM:
> > -		off += _ldst_peripheral(pl330, dry_run, &buf[off], pxs,
> > -			transfer_length, SINGLE);
> > +		/*
> > +		 * dregs_len = (total bytes - BURST_TO_BYTE(bursts, ccr)) /
> > +		 *             BRST_SIZE(ccr)
> > +		 * the dregs len must be smaller than burst len,
> > +		 * so, for higher efficiency, we can modify CCR
> > +		 * to use a reduced size burst len for the dregs.
> > +		 */
> > +		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_peripheral(pl330, dry_run, &buf[off], pxs, 1,
> > +					BURST);
> >   		break;
> >   
> >   	case DMA_MEM_TO_MEM:
> > @@ -2221,9 +2234,7 @@ static bool pl330_prep_slave_fifo(struct dma_pl330_chan *pch,
> >   
> >   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)
> > +	if (max_burst_len > PL330_MAX_BURST)
> >   		return PL330_MAX_BURST;
> >   	else if (max_burst_len < 1)
> >   		return 1;
> > @@ -3128,8 +3139,7 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id)
> >   	pd->dst_addr_widths = PL330_DMA_BUSWIDTHS;
> >   	pd->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
> >   	pd->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
> > -	pd->max_burst = ((pl330->quirks & PL330_QUIRK_BROKEN_NO_FLUSHP) ?
> > -			 1 : PL330_MAX_BURST);
> > +	pd->max_burst = PL330_MAX_BURST;
> >   
> >   	ret = dma_async_device_register(pd);
> >   	if (ret) {
> > --
> > 2.7.4
--