From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [RFC][PATCH 0/7] OMAP4 cpuidle cleanup Date: Wed, 21 Mar 2012 11:59:21 +0100 Message-ID: <4F69B489.9070004@linaro.org> References: <1332322070-24577-1-git-send-email-daniel.lezcano@linaro.org> <4F69A4A5.5020208@linaro.org> <4F69A5BA.1080804@ti.com> <4F69B0D1.6020608@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:54302 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752347Ab2CUK7Y (ORCPT ); Wed, 21 Mar 2012 06:59:24 -0400 Received: by bkcik5 with SMTP id ik5so778188bkc.19 for ; Wed, 21 Mar 2012 03:59:23 -0700 (PDT) In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Shilimkar, Santosh" Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linaro-dev@lists.linaro.org On 03/21/2012 11:49 AM, Shilimkar, Santosh wrote: > On Wed, Mar 21, 2012 at 4:13 PM, Daniel Lezcano > wrote: >> On 03/21/2012 10:56 AM, Santosh Shilimkar wrote: >>> >>> On Wednesday 21 March 2012 03:21 PM, Daniel Lezcano wrote: >>>> >>>> On 03/21/2012 10:36 AM, Shilimkar, Santosh wrote: >>>>> >>>>> On Wed, Mar 21, 2012 at 2:57 PM, Daniel Lezcano >>>>> wrote: >>>>>> >>>>>> This patchset is a proposition to improve a bit the code. >>>>>> The changes are code cleanup and does not change the behavior of= the >>>>>> driver itself. >>>>>> >>>>> Thanks. Will have a look at your series. >>>> >>>> >>>> Cool, thanks. >>>> >>>>>> A couple a things call my intention. Why the cpuidle device is s= et >>>>>> for cpu0 only >>>>> >>>>> Because the mainline code CPUIDLE is supported along with CPUhotp= lug. >>>>> This is going to change though with Couple CPUIDLE and correspond= ing >>>>> OMAP updates. >>>> >>>> >>>> Ok, thanks for the information. I will look deeper. What happens t= o cpu1 >>>> when it is online and has nothing to do ? >>>> >>>>>> and why the WFI is not used ? >>>>>> >>>>> I didn't get this question. Do you mean the generic WFI? >>>> >>>> >>> I execute default idle loop. >> >> >> So is it not possible to add a cpuidle device for cpu1 and define on= ly one >> state for the 'wfi-for-omap' ? >> > That's how my post was handling it. But after the review Kevin sugges= ted > me to drop the CPU1 shallow state since it was same as default idle. Ok, thanks. I am asking that because the more I am looking at the=20 different SoCs cpuidle drivers, the more I am convinced we can factor=20 out more code across SoCs. >>>> yes. >>>> >>>>> If yes, then, it's mainly because OMAP need additional >>>>> custom barriers. >>>> >>>> >>>> Ah, ok. I am not sure if it is possible but that may be cool if we= can >>>> call cpu_do_idle instead with additional barrier. >>>> >>> There is no need. Since code around WFI is customised, it make no s= ense >>> to call cpu_do_idle(0 ofr only that instruction sake. >> >> >> For my personal information, why the WFI is customised for omap4 ? >> > OMAP4 silicon has couple of hardware issues around interconnect > and needs to drain the axi buffers with strongly order writes to > ensure that data reaches to peripherals and not get stuck. That > lead to have custom function. Note that, the wfi instruction > itself is same. Thanks for the explanation. -- Daniel --=20 Linaro.org =E2=94=82 Open source software fo= r ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html