On Mon, Nov 19, 2012 at 09:19:15AM -0700, Mark A. Greer wrote:
> On Mon, Nov 19, 2012 at 11:01:44AM +0100, Peter Ujfalusi wrote:
> > Hi,
> >
> > On 10/19/2012 12:20 AM, Mark A. Greer wrote:
> > > Enable DMA prefetching by setting the 'OMAP_DMA_DST_SYNC_PREFETCH'
> > > flag whenever there is a destination synchronized DMA transfer.
> > > Prefetching is not allowed on source synchronized DMA transfers.
> > >
> > > Enabling prefetch significantly improves DMA performance.
> > > For example, running 'modprobe tcrypt sec=2 mode=403' which
> > > exercises the omap-sham driver on an am37x EVM yeilds the
> > > following results:
> >
> > > drivers/dma/omap-dma.c | 4 ++--
> > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c
> > > index bb2d8e7..aadddb2 100644
> > > --- a/drivers/dma/omap-dma.c
> > > +++ b/drivers/dma/omap-dma.c
> > > @@ -310,7 +310,7 @@ static struct dma_async_tx_descriptor *omap_dma_prep_slave_sg(
> > > dev_addr = c->cfg.dst_addr;
> > > dev_width = c->cfg.dst_addr_width;
> > > burst = c->cfg.dst_maxburst;
> > > - sync_type = OMAP_DMA_DST_SYNC;
> > > + sync_type = OMAP_DMA_DST_SYNC | OMAP_DMA_DST_SYNC_PREFETCH;
> >
> > This should be:
> > - sync_type = OMAP_DMA_DST_SYNC;
> > + sync_type = OMAP_DMA_DST_SYNC_PREFETCH;
>
> Ah, right. I will fix.
>
> > > } else {
> > > dev_err(chan->device->dev, "%s: bad direction?\n", __func__);
> > > return NULL;
> > > @@ -387,7 +387,7 @@ static struct dma_async_tx_descriptor *omap_dma_prep_dma_cyclic(
> > > dev_addr = c->cfg.dst_addr;
> > > dev_width = c->cfg.dst_addr_width;
> > > burst = c->cfg.dst_maxburst;
> > > - sync_type = OMAP_DMA_DST_SYNC;
> > > + sync_type = OMAP_DMA_DST_SYNC | OMAP_DMA_DST_SYNC_PREFETCH;
> >
> > We should not enable the prefetch for cyclic right now. We will investigate it
> > more.
>
> OK. I'll send a patch in a few minutes.
https://patchwork.kernel.org/patch/1765941/
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