On Wednesday, November 04, 2015 08:59:43 AM Kevin Hilman wrote: > Vinod Koul <vinod.koul@xxxxxxxxx> writes: > > > On Tue, Nov 03, 2015 at 01:25:09PM -0800, Kevin Hilman wrote: > >> >>>>> /* Enable clock before accessing register */ > >> >>>>> - ret = tegra_dma_runtime_resume(dev); > >> >>>>> + ret = pm_runtime_get_sync(dev); > >> >>>> > >> >>>> If you are runtime suspended then core will runtime resume you before > >> >>>> invoking suspend, so why do we need this > >> >>> > >> >>> Is this change now in the mainline? Do you have commit ID for that? > >> >>> > >> >>> I recall the last time we discussed this that Rafael said that they were > >> >>> going to do that, but he said as a rule of thumb if you need to resume > >> >>> it, resume it [0]. > >> >> > >> >> IIRC this has been always the behaviour, at least I see this when I test the > >> >> devices > >> > > >> > I have been doing some testing today and if the DMA is runtime > >> > suspended, then I don't see it runtime resumed before suspend is called. > >> > > >> > Can you elborate on "at least I see this when I test the devices"? What > >> > are you looking at? Are you using kernel function tracers in some way? > >> > >> The PM core does a _get_noresume()[1] which tries to prevent runtime > >> suspends *during* a system suspend. However, the PM core should not be > >> doing an actual runtime resume of the device, so if the device is > >> already runtime suspended, it will not be runtime resumed by the core, > >> so if the driver needs it to be runtime resumed, it needs to do it > >> itself. > > > > + Rafael > > > > This is contrariry to what I see, If my driver is runtime suspended and on > > suspend, it gets runtime resumed and then suspended > > Since I was late to the thread, can you explain what kind of driver and > on what bus type you're seeing this behavior? > > It could be that your bus-type is doing something, but I don't think it > should be the PM core. Right. Bus types do that, the core doesn't. The ACPI PM domain does that too for some devices. So Vinod, more details, please. Thanks, Rafael -- 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
