On Tue, Nov 28, 2017 at 12:09:06PM -0600, Grygorii Strashko wrote: > > > On 11/23/2017 05:06 AM, Ladislav Michl wrote: > > On Thu, Nov 23, 2017 at 11:26:04AM +0100, Ladislav Michl wrote: > > > On Thu, Nov 23, 2017 at 10:35:42AM +0100, Ladislav Michl wrote: > > > > On Thu, Nov 16, 2017 at 03:04:48PM -0600, Grygorii Strashko wrote: > > > > [snip] > > > > > I recommend to disable CPU idle completely in config and re-check test, > > > > > before continue with other things. > > > > > > > > Strangely enough latency is much worse with CONFIG_CPU_IDLE disabled. > > > > > > While it is better with: > > > CONFIG_HZ_PERIODIC=y > > > CONFIG_CPU_FREQ=n > > > CONFIG_PM=n > > > > > > But both ehci and musb does not see any device connected and: > > [snip] > > > > The culprit here is CONFIG_PM. With CONFIG_PM disabled latency jitter is > > about 30us, which is pretty good for general purpose OS. But some drivers > > do not work without CONFIG_PM. Suggestions? > > Not sure OMAP ever expected to fully work with CONFIG_PM=n > > You can try play with HWMOD props, like add flags to gpio hwmods: > HWMOD_NO_OCP_AUTOIDLE > HWMOD_NO_IDLE > HWMOD_CLKDM_NOAUTO And that did the trick! Well, almost. 'ti,no-idle' to gpio5 node and Tony's suggestion to allow only C1 cpuidle state gives almost as good jitter as with CONFIG_PM disabled. Just out of curiosity, I'll try with -rt patch. 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
