Hi Greg, On Tue, Nov 28, 2017 at 08:33:28AM +0100, Greg KH wrote: > On Mon, Nov 27, 2017 at 11:08:33PM +0100, Ladislav Michl wrote: > > Hi there, > > > > USB hosts do not discover any connected device on OMAP3 based board > > with CONFIG_PM=n. Just enabling this option is enough to restore working > > behaviour. Nothing unusual in log. Tested 4.14.2 and 4.15-rc1. I know > > a lot of stuff depends on CONFIG_PM, but is this expected behaviour? > > Neither EHCI nor MUSB is working without CONFIG_PM. > > What bus type is your controllers on? PCI? platform? Something else? Platform controllers inside OMAP3630 Soc. > And yes, perhaps this is to be expected, why would you not want > CONFIG_PM to be enabled? :) For a start, I know Linux is general purpose OS and I know I cannot expect low latency or low jitter when dealing with interrupts. Original problem is described here: https://www.spinics.net/lists/linux-omap/msg140081.html Shortly, with CONFIG_PM jitter of GPIO interrupt is about 350us which renders IR receiver unuseable - is cannot reliably decode IR protocol (gpio-ir-recv is used). With CONFIG_PM disabled, jitter is around 30us and that's enough to make IR decoders work. And as I was unable to fix it, nor anyone provided useful hint, I though I could work around problem from another side. And here we are... Thank you, ladis -- 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
