On Tuesday 28 January 2014 13:05:10 Arnd Bergmann wrote: > On Tuesday 28 January 2014 17:02:42 Vinod Koul wrote: > > On Tue, Jan 28, 2014 at 11:17:57AM +0000, Russell King - ARM Linux wrote: > > > On Tue, Jan 28, 2014 at 10:16:53AM +0100, Arnd Bergmann wrote: > > > > On Tuesday 28 January 2014 10:05:35 Lars-Peter Clausen wrote: > > > > > Why does the direction needs to be specified in specifier? I see two > > > > > options, either the direction per is fixed in hardware. In that case the DMA > > > > > controller node should describe which channel is which direction. Or the > > > > > direction is not fixed in hardware and can be changed at runtime in which > > > > > case it should be set on a per descriptor basis. > > > > > > > > Normally the direction is implied by dmaengine_slave_config(). > > > > > > No. The direction argument in there is deprecated - we've been talking > > > about removing it for some time. > > > > > > DMA engine drivers should store all parameters of the configuration, and > > > then select the appropriate ones when preparing a transfer (which itself > > > involves a direction.) > > > > Right all the prep_ calls for slave cases have explcit direction argument so > > sending it using slave config makes no sense. So will remove it after the merge > > window closes and fix > > Ok, thanks for clearing up my mistake. However, the argument remains: > the direction doesn't need to be in the DT DMA descriptor since it > gets set by software anyway. On a related note, should we try to remove the slave_id field from the slave config structure as well? I believe it is still used by the shmobile dma engine in non-DT mode, but that is inconsistent with how all the others work, and with what the same driver does for DT. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
