Re: [RFC/PATCH] Stop Apple i2s DMA gracefully

[Johannes Berg <johannes@sipsolutions.net>]

On Sun, 2006-10-29 at 15:19 +1100, Paul Mackerras wrote:

>  	case SNDRV_PCM_TRIGGER_STOP:
>  	case SNDRV_PCM_TRIGGER_SUSPEND:
>  		if (!pi->dbdma_ring.running) {
>  			result = -EALREADY;
>  			goto out_unlock;
>  		}
> +		pi->dbdma_ring.running = 0;
>  
> -		/* turn off all relevant bits */
> -		out_le32(&pi->dbdma->control,
> -			 (RUN | WAKE | FLUSH | PAUSE) << 16);
> -		{
> -			/* FIXME: move to own function */
> -			int timeout = 5000;
> -			while ((in_le32(&pi->dbdma->status) & RUN)
> -			       && --timeout > 0)
> -				udelay(1);
> -			if (!timeout)
> -				printk(KERN_ERR
> -				       "i2sbus: timed out turning "
> -				       "off dbdma engine!\n");
> -		}
> +		/* Set the S0 bit to make the DMA branch to the stop cmd */
> +		out_le32(&pi->dbdma->control, (1 << 16) | 1);
> +		pi->dbdma_ring.stopping = 1;

Something that just crossed my mind because Ben was complaining about
suspend/resume breakage... In the suspend case we actually have to make
sure to have DMA stopped, no?

johannes

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