From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kever Yang Subject: Re: [RESEND PATCH] ARM: dts: make arch-timer always on in rk3288 soc Date: Fri, 29 Aug 2014 08:35:16 +0800 Message-ID: <53FFCAC4.7030702@rock-chips.com> References: <1409190017-12656-1-git-send-email-kever.yang@rock-chips.com> <20140828091758.GB14650@leverpostej> <20140828151121.GM14650@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140828151121.GM14650@leverpostej> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Rutland Cc: "heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org" , "dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org" , "sonnyrao-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org" , "addy.ke-TNX95d0MmH7DzftRWevZcw@public.gmane.org" , "cf-TNX95d0MmH7DzftRWevZcw@public.gmane.org" , "xjq-TNX95d0MmH7DzftRWevZcw@public.gmane.org" , "wulf-TNX95d0MmH7DzftRWevZcw@public.gmane.org" , "lyz-TNX95d0MmH7DzftRWevZcw@public.gmane.org" , "hj-TNX95d0MmH7DzftRWevZcw@public.gmane.org" , "huangtao-TNX95d0MmH7DzftRWevZcw@public.gmane.org" , Rob Herring , Pawel Moll , Ian Campbell , Kumar Gala , Russell King , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org List-Id: devicetree@vger.kernel.org Mark, Thanks for your reply and advice. On 08/28/2014 11:11 PM, Mark Rutland wrote: > On Thu, Aug 28, 2014 at 10:17:58AM +0100, Mark Rutland wrote: >> Hi Kever, >> >> On Thu, Aug 28, 2014 at 02:40:17AM +0100, Kever Yang wrote: >>> We need use the hrtimer, which need the arch-timer to be 'always-on' >> I asked a question on the last posting [1]. Can you please confirm >> either way? >> >> Thanks, >> Mark. >> >> [1] lists.infradead.org/pipermail/linux-arm-kernel/2014-August/282327.html > To clarify: if there are low power states that the CPU can enter where > we lose state, then this patch isn't correct. rk3288 has low power state and may turn off the cpu power domain which will lost any logic state in cpu. > > A more general approach would be to enable the broadcast hrtimer for > arm, as has been done for arm64. > > See commit 5d1638acb9f6 (tick: Introduce hrtimer based broadcast) which > introduced the broadcast hrtimer, and commit 9358d755bd5c (arm64: > kernel: initialize broadcast hrtimer based clock event device) which > added the requisite plumbing for arm64. I'll going to implement this and send another patch. Thanks. -Kever -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html