[alsa-devel] [PATCH 01/11] dma: imx-sdma: make channel0 operations atomic

[Richard Zhao]

On Fri, Apr 27, 2012 at 09:55:44AM +0200, Sascha Hauer wrote:
> On Fri, Apr 27, 2012 at 03:02:55PM +0800, Richard Zhao wrote:
> > device_prep_dma_cyclic may be call in audio trigger function which is
> > atomic context, so we make it atomic too.
> > 
> >  - change channel0 lock to spinlock.
> >  - Use polling to wait for channel0 finish running.
> > 
> > Signed-off-by: Lothar Waßmann <LW at KARO-electronics.de>
> > Signed-off-by: Richard Zhao <richard.zhao at freescale.com>
> > ---
> >  drivers/dma/imx-sdma.c |   57 +++++++++++++++++++++++++++--------------------
> >  1 files changed, 33 insertions(+), 24 deletions(-)
> > 
> > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> > index fddccae..fc49ffa 100644
> > --- a/drivers/dma/imx-sdma.c
> > +++ b/drivers/dma/imx-sdma.c
> > @@ -24,7 +24,7 @@
> >  #include <linux/mm.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/clk.h>
> > -#include <linux/wait.h>
> > +#include <linux/delay.h>
> >  #include <linux/sched.h>
> >  #include <linux/semaphore.h>
> >  #include <linux/spinlock.h>
> > @@ -324,7 +324,7 @@ struct sdma_engine {
> >  	struct dma_device		dma_device;
> >  	struct clk			*clk_ipg;
> >  	struct clk			*clk_ahb;
> > -	struct mutex			channel_0_lock;
> > +	spinlock_t		channel_0_lock;
> >  	struct sdma_script_start_addrs	*script_addrs;
> >  };
> >  
> > @@ -402,19 +402,31 @@ static void sdma_enable_channel(struct sdma_engine *sdma, int channel)
> >  }
> >  
> >  /*
> > - * sdma_run_channel - run a channel and wait till it's done
> > + * sdma_run_channel0 - run a channel and wait till it's done
> >   */
> > -static int sdma_run_channel(struct sdma_channel *sdmac)
> > +static int sdma_run_channel0(struct sdma_channel *sdmac)
> 
> Renaming this to sdma_run_channel0 is fine, but then the argument should
> be changed to struct sdma_engine. It makes no sense to say in the
> function name that this function is channel 0 only and at the same time
> allow to pass in an arbitrary other channel.
Correct. Thanks.

Richard
> 
> Sascha
> 
> 
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