From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH] cpufreq: qoriq: optimize the CPU frequency switching time Date: Tue, 16 Jun 2015 01:46:16 +0200 Message-ID: <1528534.foUvvcDHWW@vostro.rjw.lan> References: <1433399142-18324-1-git-send-email-Yuantian.Tang@freescale.com> <20150604063636.GH11325@linux> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <20150604063636.GH11325@linux> Sender: cpufreq-owner@vger.kernel.org To: Viresh Kumar Cc: Yuantian.Tang@freescale.com, linux-pm@vger.kernel.org, cpufreq@vger.kernel.org, linuxppc-dev@lists.ozlabs.org List-Id: linux-pm@vger.kernel.org On Thursday, June 04, 2015 12:06:36 PM Viresh Kumar wrote: > On 04-06-15, 14:25, Yuantian.Tang@freescale.com wrote: > > From: Tang Yuantian > > > > Each time the CPU switches its frequency, the clock nodes in > > DTS are walked through to find proper clock source. This is > > very time-consuming, for example, it is up to 500+ us on T4240. > > Besides, switching time varies from clock to clock. > > To optimize this, each input clock of CPU is buffered, so that > > it can be picked up instantly when needed. > > > > Since for each CPU each input clock is stored in a pointer > > which takes 4 or 8 bytes memory and normally there are several > > input clocks per CPU, that will not take much memory as well. > > Not sure how it got included in this form in the first place. :) > > > Signed-off-by: Tang Yuantian > > --- > > drivers/cpufreq/qoriq-cpufreq.c | 32 +++++++++++++++++++++----------- > > 1 file changed, 21 insertions(+), 11 deletions(-) > > Acked-by: Viresh Kumar Queued up for 4.2, thanks! -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.