Re: [PATCH v2] ARM: OMAP: SDMA: Fix omap_stop_dma() API for channel linking

[Tony Lindgren <tony@atomide.com>]

* Shilimkar, Santosh <santosh.shilimkar@ti.com> [091019 23:29]:
> Tony,
> > -----Original Message-----
> > From: Tony Lindgren [mailto:tony@atomide.com]
> > Sent: Monday, October 19, 2009 10:54 PM
> > To: Shilimkar, Santosh
> > Cc: linux-omap@vger.kernel.org; S, Venkatraman; Hari n; Jarkko
> > Nikula
> > Subject: Re: [PATCH v2] ARM: OMAP: SDMA: Fix omap_stop_dma() API for
> > channel linking
> > 
> > * Santosh Shilimkar <santosh.shilimkar@ti.com> [091015 00:07]:
> > > OMAP sDMA driver API omap_stop_dma() doesn't really stop the dma
> > when used
> > > in linking scenario. This patch fixes the same.
> > >
> > > Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
> > > Signed-off-by: Venkatraman S <svenkatr@ti.com>
> > > Reviewed-By: Tony Lindgren <tony@atomide.com>
> > > CC: Hari n <hari.zoom@gmail.com>
> > > CC: Jarkko Nikula <jhnikula@gmail.com>
> > > ---
> > >  arch/arm/plat-omap/dma.c |    5 +++++
> > >  1 files changed, 5 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
> > > index fd3154a..1c933b4 100644
> > > --- a/arch/arm/plat-omap/dma.c
> > > +++ b/arch/arm/plat-omap/dma.c
> > > @@ -987,6 +987,11 @@ void omap_stop_dma(int lch)
> > >  			/* Mark the current channel */
> > >  			dma_chan_link_map[cur_lch] = 1;
> > >
> > > +			/* Disable the DMA channel */
> > > +			l = dma_read(CCR(lch));
> > > +			l &= ~OMAP_DMA_CCR_EN;
> > > +			dma_write(l, CCR(lch));
> > > +
> > >  			disable_lnk(cur_lch);
> > >
> > >  			next_lch = dma_chan[cur_lch].next_lch;
> > 
> > Hmm, I'm thinking it should be like this instead to also clear
> > the dma_chan[lch].flags instead of returning before that.
> > 
> > Can you try this with your testcase?
> This works too. OMAP1 doesn't support channel linking so this is fine. In case it was, then it would have been an issue.

OK, I've updated your original patch with these changes, and
will add it to omap-fixes.

Regards,

Tony

> 
> > diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
> > index 0eb676d..b53125f 100644
> > --- a/arch/arm/plat-omap/dma.c
> > +++ b/arch/arm/plat-omap/dma.c
> > @@ -978,6 +978,14 @@ void omap_stop_dma(int lch)
> >  {
> >  	u32 l;
> > 
> > +	/* Disable all interrupts on the channel */
> > +	if (cpu_class_is_omap1())
> > +		dma_write(0, CICR(lch));
> > +
> > +	l = dma_read(CCR(lch));
> > +	l &= ~OMAP_DMA_CCR_EN;
> > +	dma_write(l, CCR(lch));
> > +
> >  	if (!omap_dma_in_1510_mode() && dma_chan[lch].next_lch != -1)
> > {
> >  		int next_lch, cur_lch = lch;
> >  		char dma_chan_link_map[OMAP_DMA4_LOGICAL_DMA_CH_COUNT];
> > @@ -995,18 +1003,8 @@ void omap_stop_dma(int lch)
> >  			next_lch = dma_chan[cur_lch].next_lch;
> >  			cur_lch = next_lch;
> >  		} while (next_lch != -1);
> > -
> > -		return;
> >  	}
> > 
> > -	/* Disable all interrupts on the channel */
> > -	if (cpu_class_is_omap1())
> > -		dma_write(0, CICR(lch));
> > -
> > -	l = dma_read(CCR(lch));
> > -	l &= ~OMAP_DMA_CCR_EN;
> > -	dma_write(l, CCR(lch));
> > -
> >  	dma_chan[lch].flags &= ~OMAP_DMA_ACTIVE;
> >  }
> >  EXPORT_SYMBOL(omap_stop_dma);
>