Vinod Koul <vinod.koul@xxxxxxxxx> writes: > On Thu, Dec 08, 2016 at 11:44:53AM +0000, Måns Rullgård wrote: >> Vinod Koul <vinod.koul@xxxxxxxxx> writes: >> >> > On Wed, Dec 07, 2016 at 04:45:58PM +0000, Måns Rullgård wrote: >> >> Vinod Koul <vinod.koul@xxxxxxxxx> writes: >> >> >> >> > On Tue, Dec 06, 2016 at 01:14:20PM +0000, Måns Rullgård wrote: >> >> >> >> >> >> That's not going to work very well. Device drivers typically request >> >> >> dma channels in their probe functions or when the device is opened. >> >> >> This means that reserving one of the few channels there will inevitably >> >> >> make some other device fail to operate. >> >> > >> >> > No that doesnt make sense at all, you should get a channel only when you >> >> > want to use it and not in probe! >> >> >> >> Tell that to just about every single driver ever written. >> > >> > Not really, few do yes which is wrong but not _all_ do that. >> >> Every driver I ever looked at does. Name one you consider "correct." > > That only tells me you haven't looked enough and want to rant! > > FWIW look at ALSA-dmaengine lib, thereby every audio driver that uses it. I > could find other examples and go on and on, but that's besides the point and > looks like you don't want to listen to people telling you something.. ALSA is a particularly poor example. ALSA drivers request a dma channel at some point between the device being opened and playback (or capture) starting. They then set up a cyclic transfer that runs continuously until playback is stopped. It's a completely different model of operation than we're talking about here. -- Måns Rullgård -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
