Messages in this thread | | | Date | Wed, 1 Oct 2014 08:21:49 -0700 | Subject | Re: [PATCH v3] clocksource: arch_timer: Allow the device tree to specify the physical timer | From | Doug Anderson <> |
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Hi,
On Mon, Sep 29, 2014 at 10:30 AM, Sonny Rao <sonnyrao@chromium.org> wrote: > On Fri, Sep 26, 2014 at 3:00 AM, Mark Rutland <mark.rutland@arm.com> wrote: >> On Thu, Sep 11, 2014 at 06:00:01PM +0100, Doug Anderson wrote: >>> +** Optional properties: >>> + >>> +- arm,use-physical-timer : Don't ever use the virtual timer, just use the >>> + physical one. Only supported for ARM (not ARM64). >> >> I'm still not keen on telling the kernel what to do rather than >> describing the actual state of affairs and having the kernel decide what >> to do. Perhaps what we actually need is: >> >> - cntvoff-not-fw-configured: Firmware does not configure CNTVOFF, which >> may reset to (different) arbitrary values on each CPU. >> >> This also doesn't describe that CNTHCTL.PL1PC(T)EN must both be 1. While >> that is the reset state, it still feels dodbgy to me to rely on that. >> >> Mark. > > Mark, I'm happy to repost it with that name for Doug. > > I think it's fair to describe this state in the binding, and if a > firmware were to put this property into the device-tree for and > CNTHCTL.PL1P(T)CEN also have configured to 0, then the kernel can > merely consider that to be a broken usage of this property. We > certainly can't protect against all of the possible invalid states > caused and probably shouldn't try. If we implement something like > Christopher's suggestion for transitioning from secure svc to NS hyp > mode then the kernel can simply ignore this property at that point.
I've already talked in person to Sonny about this, but just to post on the list too... I think Mark Rutland's suggestion is a good one and I'm more than happy for Sonny to repost that way for me. Thanks! :)
-Doug
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