From mboxrd@z Thu Jan 1 00:00:00 1970 From: Santosh Shilimkar Subject: Re: [PATCH, RFC 2/8] ARM: twd: register clock event for 1 core SMP Date: Tue, 19 Feb 2013 17:50:33 +0530 Message-ID: <51236E11.1030900@ti.com> References: <51235076.8040200@ti.com> <20130219121400.GP23197@arwen.pp.htv.fi> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130219121400.GP23197-S8G//mZuvNWo5Im9Ml3/Zg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: balbi-l0cyMroinI0@public.gmane.org Cc: Afzal Mohammed , Russell King , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Sekhar Nori , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Nicolas Pitre , Will Deacon , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Rob Herring , Syed Mohammed Khasim , linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On Tuesday 19 February 2013 05:44 PM, Felipe Balbi wrote: > On Tue, Feb 19, 2013 at 03:44:14PM +0530, Santosh Shilimkar wrote: >> On Monday 18 February 2013 05:07 PM, Afzal Mohammed wrote: >>> Register percpu local timer for scheduler tick in the case of one core >>> SMP configuration. In other cases - secondary cpu's as well as boot >>> cpu's having more than one core, this is being registered as per >>> existing boot flow, with a difference that they happens after delay >>> calibration. Registering the clock for tick in case of one core should >>> be done before Kernel calibrates delay (this is required to boot, >>> unless local timer is the only one registered for tick). Registering >>> twd local timer at init_time (which platforms are doing now) helps >>> achieve that with the proposed change. >>> >>> This helps in an almost booting Kernel (minimal) by only relying on >>> ARM parts for an A9 one core SMP. >>> >>> Signed-off-by: Afzal Mohammed >>> --- >> As mentioned in cover-letter, I don't think we have good >> reasoning to make TWD to work with UP configuration. Even >> you fix the timer code, there are more cascaded dependencies >> which is not worth the effort. > > if CONFIG_SMP_ON_UP is enabled, smp_twd.c can still be compiled, right ? > Yep though just from deps pesrpective TWD is made available for ARM SMP machines as below config HAVE_ARM_TWD bool depends on SMP Regards, Santosh