On Mon, Feb 04, 2013 at 05:41:53PM +0200, Felipe Balbi wrote: > Hi, > > On Fri, Feb 01, 2013 at 09:30:03PM +0000, Russell King - ARM Linux wrote: > > > > > I guess to make the MUSB side simpler we would need musb-dma-engine glue > > > > > to map dmaengine to the private MUSB API. Then we would have some > > > > > starting point to also move inventra (and anybody else) to dmaengine > > > > > API. > > > > > > > > Why? Inventra is a dedicated device's private DMA controller, why make > > > > universal DMA driver for it? > > > > > > because it doesn't make sense to support multiple DMA APIs. We can check > > > from MUSB's registers if it was configured with Inventra DMA support and > > > based on that we can register MUSB's own DMA Engine to dmaengine API. > > > > Hang on. This is one of the DMA implementations which is closely > > coupled with the USB and only the USB? If it is... > > > > I thought this had been discussed _extensively_ before. I thought the > > resolution on it was: > > 1. It would not use the DMA engine API. > > 2. It would not live in arch/arm. > > 3. It would be placed nearby the USB driver it's associated with. > > > > (1) because we don't use APIs just for the hell of it - think. Do we > > use the DMA engine API for PCI bus mastering ethernet controllers? No. > > Do we use it for PCI bus mastering SCSI controllers? No. Because the > > DMA is integral to the rest of the device. > > that's not really a fair comparison, however. MUSB is used with several > DMA engines. I only mentioned it because it _was_ brought up as an argument against using the DMA engine API in the previous discussions. I'm just reminding people what was discussed. > Considering all of the above, it's far better to use DMA engine and get > rid of all the mess. Which is what both you and I have been saying for the last 3 or so years on this subject... -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
