On Fri, 2013-05-17 at 02:19 +0800, Stephen Warren wrote: > On 05/16/2013 03:53 AM, Joseph Lo wrote: > > On Thu, 2013-05-16 at 07:38 +0800, Stephen Warren wrote: > >> On 05/15/2013 04:27 AM, Joseph Lo wrote: > >>> Tegra 114 is different with other Tegra SoC chips. It using ARM Cortex-A15 > >>> as CPU core and a enhanced flow controller for CPU power control. So > >>> we need to skip some code that was for Contex-A9 and some other support > >>> code that was for other Tegra SoC chips. Then adding the proper power up > >>> and hot plug control for Tegra114. > >> > >> This series mostly works OK, but I see one problem: I can't hotunplug > >> CPU0, which the commit descriptions and code changes imply I should be > >> able to do: > >> > >> root@localhost:~# echo 0 > /sys/devices/system/cpu/cpu0/online > >> -bash: echo: write error: Operation not permitted > > > > I want to provide this function originally. But I found the > > tegra_cpu_disable() was removed recently. It was replaced by the common > > cpu_disable() function that didn't allow CPU0 to be un-plugged. > > Is there a specific reason for that; is there some problem in the core > ARM code that implies CPU0 should never be disabled? > I think the CPU0 is the boot CPU for most of the case. We always need at least one CPU online. That assumes to be the boot CPU. > > But I had verified the CPU0 is OK to be un-plugged on the older > > linux-next branch that tegra_cpu_disable() watn't removed yet. > > > > Do you want me to add them back to support this function for Tegra114? > > If there is a problem removing CPU0 in the core code, the functionality > of this series is OK, although it's probably worth removing the parts > that attempt to make CPU0 hot-unpluggable to reduce the diff size. > > If there's no problem removing CPU0, it'd be good to make it work, > although that could be done in followon patches. OK. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
