[PATCH V6 2/2] dmaengine: add helper function to request a slave DMA channel
Arnd Bergmann
arnd at arndb.de
Mon Sep 17 21:59:27 EST 2012
On Monday 17 September 2012, Vinod Koul wrote:
> On Fri, 2012-09-14 at 17:41 -0500, Jon Hunter wrote:
> > +/**
> > + * dma_request_slave_channel - try to allocate an exclusive slave
> > channel
> > + * @dev: pointer to client device structure
> > + * @name: slave channel name
> > + */
> > +struct dma_chan *dma_request_slave_channel(struct device *dev, char *name)
> > +{
> > + /* If device-tree is present get slave info from here */
> > + if (dev->of_node)
> > + return of_dma_request_slave_channel(dev->of_node, name);
> > +
> Shouldn't this be conditionally compiled only when OF is built. I think
> this might be problematic for systems which doesn't have device tree.
> Or perhaps you can declare these symbols as dummy in of_dma.h when
> device tree is not selected.
Right, good point. I'd prefer the dummy functions, since that is in line
with what a lot of other subsystems do:
#ifdef CONFIG_OF
extern int of_dma_controller_register(struct device_node *np,
struct dma_chan *(*of_dma_xlate)
(struct of_phandle_args *, struct of_dma *),
void *data);
extern void of_dma_controller_free(struct device_node *np);
extern struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
char *name);
extern struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma);
#else
static inline int of_dma_controller_register(struct device_node *np,
struct dma_chan *(*of_dma_xlate)
(struct of_phandle_args *, struct of_dma *),
void *data)
{
return -ENODEV;
}
static inline void of_dma_controller_free(struct device_node *np)
{
}
static inline struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
char *name)
{
return NULL;
}
static inline struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma)
{
return NULL;
}
#endif
I believe that Jon is on vacation this week, so if this is the only issue
holding up the merge, maybe you can change this in his patch directly, or
I can send an updated version if you prefer.
Arnd
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