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

[Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

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-bxm8fMRDkQLDiMYJYoSAnRvVK+yQ3ZXh@public.gmane.org>
> Signed-off-by: Richard Zhao <richard.zhao-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> ---
>  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.

Sascha


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