From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Shilimkar, Santosh" Subject: Re: [PATCH v4 3/5] ARM: topology: Update cpu_power according to DT information Date: Mon, 9 Jul 2012 20:07:14 +0530 Message-ID: References: <1341826026-6504-1-git-send-email-vincent.guittot@linaro.org> <1341826026-6504-4-git-send-email-vincent.guittot@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linaro-dev-bounces-cunTk1MwBs8s++Sfvej+rw@public.gmane.org Errors-To: linaro-dev-bounces-cunTk1MwBs8s++Sfvej+rw@public.gmane.org To: Vincent Guittot Cc: linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org, a.p.zijlstra-/NLkJaSkS4VmR6Xm/wNWPw@public.gmane.org, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org, yong.zhang0-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, namhyung-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linaro-dev-cunTk1MwBs8s++Sfvej+rw@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On Mon, Jul 9, 2012 at 8:06 PM, Vincent Guittot wrote: > On 9 July 2012 15:00, Shilimkar, Santosh wrote: >> On Mon, Jul 9, 2012 at 6:02 PM, Vincent Guittot >> wrote: >>> On 9 July 2012 12:55, Shilimkar, Santosh wrote: >>>> Vincent, >>>> On Mon, Jul 9, 2012 at 2:57 PM, Vincent Guittot >>>> wrote: >>>>> Use cpu compatibility field and clock-frequency field of DT to >>>>> estimate the capacity of each core of the system and to update >>>>> the cpu_power field accordingly. >>>>> This patch enables to put more running tasks on big cores than >>>>> on LITTLE ones. But this patch doesn't ensure that long running >>>>> tasks will run on big cores and short ones on LITTLE cores. >>>>> >>>>> Signed-off-by: Vincent Guittot >>>>> Reviewed-by: Namhyung Kim >>>>> --- >>>>> arch/arm/kernel/topology.c | 153 ++++++++++++++++++++++++++++++++++++++++++++ >>>>> 1 file changed, 153 insertions(+) >>>>> >>>> Sorry for not giving this comment on previous version but we should also >>>> have a way to provide the big.LITTLE information without Device Tree. >>>> May be a platform device/data. >>> >>> Hi Santosh, >>> >>> I had thought of adding such additional way to set cpu_power of >>> big.LITTLE but my conclusion was >>> -it's a new platform so it should come with DT >>> -DT is already required by other patches linked to big.LITTLE >>> (http://lists.infradead.org/pipermail/linux-arm-kernel/2012-January/080873.html) >>> -There is no device that can be easily used to get such information at >>> this early boot stage. >>> >> I see. Its new processor but it is just 1 one of the IP in an entire SOC. >> As mentioned below I was talking about full SOC support including >> all the driver subsystem with DT. >> >>>> >>>> I know we are moving DT way, but remember apart from core kernel >>>> infrastructure, to have a complete product build with DT means all the >>>> drivers must be already supporting DT which is not the case with >>>> many huge driver sub-systems like USB, display subsystem, Audio etc. >>>> >>>> Having that support would greatly help for the SOC's which have not yet >>>> reached to stage where entire SOC is DT compliant and want to use >>>> big.LITTLE infrastructure. >>> >>> Can't you support both type of devices on your platform ? You can move >>> your device to DT mode when it is supported ? >>> >> That is what eventually people end up doing who don't have >> DT ready for entire SOC. I was trying to ask whether at least some >> method is proposed(need not be merged in mainline) to have >> the big.LITTLE information parsing without DT. > > Ok, IIUC, you need a temporary methods, which doesn't need to be > merged in mainline, to set the cpu_scale field ? > Yep. Regards Santosh