Russell, On 03/29/2013 06:31 PM, Russell King - ARM Linux wrote: > On Fri, Mar 29, 2013 at 03:12:03PM +0100, Peter Ujfalusi wrote: >> Remove the use of a tasklet to start the DMA channel when issue_pending is >> called. >> The use of tasklet delays the DMA start which can cause issues at drivers, >> for example the audio drivers expect that the DMA is started right away. >> >> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx> >> --- >> Hi Russell, >> >> I know you are against removing the tasklet since you have planed to move the >> omap-dma to use runtime/dynamic DMA channel use. >> I have looked at the amba-pl08x.c driver which is doing that exactly (as you >> pointed out that to me). AMBA did not use tasklet either and I'm sure we can >> change the omap-dma driver to do the same in a same way as we could have done it >> with the tasklet use. > > It's rather sad that you're ignoring what I'm saying, and going by what > another DMA engine driver - which is self contained - is doing, rather > than listening to my arguments against that approach. The reason I send this as RFC to start a discussion to find out how we should handle this. I were to ignore what you were saying I would have just sent a PATCH instead. I don't think that the tasklet is the solution for the runtime DMA channel selection. We can do it in a same way as AMBA has been doing. In this way we can handle all cases with the same code. The pre-allocating of channels and starting the DMA right away is different issue. What need to be done anyway is to convert the remaining drivers to use dmaengine: drivers/usb/musb/tusb6010_omap.c drivers/usb/gadget/omap_udc.c drivers/mtd/onenand/omap2.c drivers/media/platform/omap3isp/isphist.c drivers/media/platform/soc_camera/omap1_camera.c drivers/media/platform/omap/omap_vout_vrfb.c When that is done we can remove the arch/arm/plat-omap/dma.c and migrate the code under dmaengine to restructure it and finally we can have runtime channel allocation. -- Péter -- 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
