On 11 February 2015 at 13:27, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote: > On 02/10, Ashwin Chaugule wrote: >> Hi Stephen, >> >> On 10 February 2015 at 20:05, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote: >> > Scorpion supports a set of local performance monitor event >> > selection registers (LPM) sitting behind a cp15 based interface >> > that extend the architected PMU events to include Scorpion CPU >> > and Venum VFP specific events. To use these events the user is >> > expected to program the lpm register with the event code shifted >> > into the group they care about and then point the PMNx event at >> > that region+group combo by writing a LPMn_GROUPx event. Add >> > support for this hardware. >> > >> > Note: the raw event number is a pure software construct that >> > allows us to map the multi-dimensional number space of regions, >> > groups, and event codes into a flat event number space suitable >> > for use by the perf framework. >> > >> > This is based on code originally written by Ashwin Chaugule and >> > Neil Leeder [1] massed to become similar to the Krait PMU support >> > code. >> >> Thanks for taking this up! >> Overall this series looks good to me, but from what I faintly >> recollect, doesn't this (and the Krait pmu code) get affected by >> powercollapse issues anymore? >> e.g. >> https://www.codeaurora.org/cgit/quic/la/kernel/msm/commit/arch/arm/kernel/perf_event_msm.c?h=msm-3.4&id=b5ca687960f0fea2f4735e83ca5c9543474c19de >> > > Right now there isn't any power collapse support in mainline so > there's no immediate problem. Once we add power collapse support > (i.e. cpuidle) to the Scorpion and Krait platforms we'll need to > do something in the perf event code to properly maintain the > counts across idle. I imagine it would be done by registering for > cpu_pm notifications and then doing the save/restore on > CPU_PM_ENTER and CPU_PM_EXIT. At least, that's what you started > doing in this patch[1]. And then it seems the patch you mention > came after that and actually did the save/restore of the counts. > > [1] https://www.codeaurora.org/cgit/quic/la/kernel/msm/commit/?h=msm-3.4&id=464983a7e991a484cac0bc0885cee4fee318d659 Right. Thats essential whenever the power collapse stuff goes in. Thanks, Ashwin. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
