On 11/29/2013 02:08 PM, Arnd Bergmann wrote: > On Monday 25 November 2013, Stephen Warren wrote: >> Well, you suggested not using of_dma_simple_xlate() since it wasn't >> appropriate. I then started to implement an open-coded xlate function, >> but found that it was 99% identical to the same thing in the mmp driver, >> and hence created a common of_dma_slave_xlate() so as not to just >> cut/paste it everywhere. Unfortunately, I only sent that patch to >> dmaengine@xxxxxxxxxxxxxxx and the DMA maintainers, and there's no >> archive of that list:-( > > Ok, I see. However, I think the need for nontrivial code to be duplicated > across drivers is not a sign that we are missing a generic xlate function > and another indirection level, but rather that we got the interface > for dma_get_slave_channel() wrong (yes, that would be my fault). > > Can you try coming up with a different method to achieve the same > where you use a different helper from the driver specific xlate > function that does not require a callback? > > I think dma_get_slave_channel is great if you have one channel per > request line and you can directly look up the channel from the > DT data, but it is not good if you have pick a channel and work > around the race. Hmm. Can you take a look at "[PATCH V4] dma: add dma_get_any_slave_channel(), for use in of_xlate()" at the link below. It still implements this via xlate, but I don't see any benefit in making drivers use a different API to request slave channels based on how the DMA controller works. http://lkml.org/lkml/2013/11/26/408 -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
