On Sun, Jun 10, 2012 at 07:19:47PM +0800, Barry Song wrote:
> 2012/6/10 Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>:
> > Dan, Vinod,
> >
> > There's a change I would like to do to the DMA slave configuration.
> > It's currently a pain to have the source and destination parameters in
> > the dma_slave_config structure as separate elements; it means when you
> > want to extract them, you end up with code in DMA engine drivers like:
> >
> > + if (dir == DMA_DEV_TO_MEM) {
> > + dev_addr = c->src_addr;
> > + dev_width = c->src_addr_width;
> > + burst = c->src_maxburst;
> > + } else if (dir == DMA_MEM_TO_DEV) {
> > + dev_addr = c->dst_addr;
> > + dev_width = c->dst_addr_width;
> > + burst = c->dst_maxburst;
> > + }
> >
> > If we redefine the structure as below, this all becomes more simple:
> >
> > + if (dir == DMA_DEV_TO_MEM)
> > + cfg = &c->dev_src;
> > + else if (dir == DMA_MEM_TO_DEV)
> > + cfg = &c->dev_dst;
>
> it seems that might mean an union in your dma_slave_cfg, but not
> co-exitense of both?
No, I want both so it's possible to select between the two when preparing
a DMA slave transfer.
> struct dma_slave_cfg {
> + union {
> struct dma_dev_cfg dev_src;
> struct dma_dev_cfg dev_dst;
> }
> bool device_fc;
> };
If you do that, the union becomes pointless, and you might as well have:
struct dma_slave_cfg {
struct dma_dev_cfg dev;
bool device_fc;
};
instead.
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
