Re: [PATCH v5 07/14] dmaengine: add dma_request_slave_channel_compat()

Matt Porter
2013-01-30T06:35:47Z

On Wed, Jan 23, 2013 at 10:28:46PM +0000, Arnd Bergmann wrote:
> On Tuesday 15 January 2013, Matt Porter wrote:
> > Adds a dma_request_slave_channel_compat() wrapper which accepts
> > both the arguments from dma_request_channel() and
> > dma_request_slave_channel(). Based on whether the driver is
> > instantiated via DT, the appropriate channel request call will be
> > made.
> >
> > This allows for a much cleaner migration of drivers to the
> > dmaengine DT API as platforms continue to be mixed between those
> > that boot using DT and those that do not.
>
> I noticed today some drivers in linux-next that rely on this patch,
> but the patch itself still missing from -next.
>
> > --- a/include/linux/dmaengine.h
> > +++ b/include/linux/dmaengine.h
> > @@ -1047,6 +1047,16 @@ void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
> > struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type);
> > struct dma_chan *net_dma_find_channel(void);
> > #define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
> > +static inline struct dma_chan
> > +*dma_request_slave_channel_compat(dma_cap_mask_t mask, dma_filter_fn fn,
> > + void *fn_param, struct device *dev,
> > + char *name)
> > +{
> > + if (dev->of_node)
> > + return dma_request_slave_channel(dev, name);
> > + else
> > + return dma_request_channel(mask, fn, fn_param);
> > +}
>
> Hmm, dma_request_channel is actually a macro that passes mask by reference,
> presumably because it can get modified by the filter function. Also, there
> may be cases where we do have an of_node but don't use the dma binding
> yet, or where dma_request_slave_channel doesn't actually use DT information
> but rather one of the other methods that Vinod was talking about adding.
>
> I think what it should look like instead is the below.

Yes, looks correct now, thanks. I've incorporated it into v6.

-Matt

>
> Arnd
>
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index bfcdecb..b6ffd7d 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -993,6 +993,19 @@ static inline void dma_release_channel(struct dma_chan *chan)
> }
> #endif
>
> +static inline struct dma_chan *__dma_request_slave_channel_compat(dma_cap_mask_t *mask,
> + dma_filter_fn fn, void *fn_param, struct device *dev,
> + char *name)
> +{
> + struct dma_chan *chan;
> +
> + chan = dma_request_slave_channel(dev, name);
> + if (chan)
> + return chan;
> +
> + return __dma_request_channel(mask, fn, fn_param);
> +}
> +
> /* --- DMA device --- */
>
> int dma_async_device_register(struct dma_device *device);
> @@ -1001,6 +1014,8 @@ void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
> struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type);
> struct dma_chan *net_dma_find_channel(void);
> #define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
> +#define dma_request_slave_channel_compat(mask, x, y, dev, name) \
> + __dma_request_slave_channel_compat(&(mask), x, y, dev, name)
>
> /* --- Helper iov-locking functions --- */
>
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