[RFC PATCH] DMA: PL330: Update PL330 DMAC to support runtime PM

[Russell King - ARM Linux]

On Wed, Jul 27, 2011 at 03:14:27PM +0900, Chanwoo Choi wrote:
> +#ifdef CONFIG_PM_RUNTIME
> +	struct dma_pl330_chan *pch;
> +	struct dma_pl330_dmac *pdmac;
> +#endif
>  
>  	dma_cap_zero(mask);
>  	dma_cap_set(info->cap, mask);
>  
>  	chan = dma_request_channel(mask, pl330_filter, (void *)dma_ch);
>  
> +#ifdef CONFIG_PM_RUNTIME
> +	pch = container_of(chan, struct dma_pl330_chan, chan);
> +	pdmac = pch->dmac;
> +
> +	pm_runtime_get_sync(pdmac->pif.dev);
> +#endif

This is not the right way to do this.  The pm runtime stuff should be
internal to the PL330 driver.  Take a moment to think about this:

You need to wake it up just before a transfer starts.  You need to
put it back to sleep just after the last transfer has finished.
That gives you a hint where the calls need to be.

That can only be done from within the PL330 driver.