linux-kernel - Re: [PATCH 6/7] dw_dmac: check if controller supports LLP

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Date:	Thu, 20 Sep 2012 12:43:26 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	viresh kumar <viresh.kumar@...aro.org>
Cc:	Vinod Koul <vinod.koul@...el.com>, spear-devel@...t.st.com,
	linux-kernel@...r.kernel.org, Hein Tibosch <hein_tibosch@...oo.es>
Subject: Re: [PATCH 6/7] dw_dmac: check if controller supports LLP

On Tue, 2012-09-18 at 12:43 +0530, viresh kumar wrote: 
> On Mon, Sep 17, 2012 at 1:09 PM, Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> wrote:
> > Some controllers have the reduced functionality where the LLP multi block
> > transfers are not supported. This patch introduces a check and refuses to deal
> > with such devices.
> >
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > ---
> >  drivers/dma/dw_dmac.c      |   35 ++++++++++++++++++++++++++++++++++-
> >  drivers/dma/dw_dmac_regs.h |    4 ++++
> >  2 files changed, 38 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
> > index fdb7d5a..00958ad 100644
> > --- a/drivers/dma/dw_dmac.c
> > +++ b/drivers/dma/dw_dmac.c
> > @@ -647,6 +647,12 @@ dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
> >         unsigned int            dst_width;
> >         u32                     ctllo;
> >
> > +       if (dwc->nollp) {
> > +               dev_dbg(chan2dev(&dwc->chan),
> > +                               "channel doesn't support LLP transfers\n");
> > +               return NULL;
> > +       }
> 
> But this could have been a single block request. Isn't it?
I think we could discard this comment in regard to comments on next
patch.


-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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