From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751936AbaIKDnY (ORCPT ); Wed, 10 Sep 2014 23:43:24 -0400 Received: from va-smtp01.263.net ([54.88.144.211]:41894 "EHLO vasmtpcom.263.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751185AbaIKDnX (ORCPT ); Wed, 10 Sep 2014 23:43:23 -0400 X-RL-SENDER: zyw@rock-chips.com X-FST-TO: dianders@chromium.org X-SENDER-IP: 127.0.0.1 X-LOGIN-NAME: zyw@rock-chips.com X-UNIQUE-TAG: X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 1 Message-ID: <5411196B.6000507@rock-chips.com> Date: Thu, 11 Sep 2014 11:39:23 +0800 From: Chris Zhong User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Doug Anderson , Lee Jones , Heiko Stuebner CC: linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, Sonny Rao , sameo@linux.intel.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mfd: RK808: Add register caching References: <1410303964-6943-1-git-send-email-dianders@chromium.org> In-Reply-To: <1410303964-6943-1-git-send-email-dianders@chromium.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/10/2014 07:06 AM, Doug Anderson wrote: > Let's define the voltatile registers (those that can't be cached) and > enable caching. The rk808 is accessed almost constantly with cpufreq > so this is really nice. > > As measured by ftrace: > before this change: cpu0_set_target() => ~2200us > after this change: cpu0_set_target() => ~500us > > Signed-off-by: Doug Anderson > --- > drivers/mfd/rk808.c | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/drivers/mfd/rk808.c b/drivers/mfd/rk808.c > index 0324422..bd02150 100644 > --- a/drivers/mfd/rk808.c > +++ b/drivers/mfd/rk808.c > @@ -29,10 +29,40 @@ struct rk808_reg_data { > int value; > }; > > +static bool rk808_is_volatile_reg(struct device *dev, unsigned int reg) > +{ > + /* > + * Notes: > + * - Technically the ROUND_30s bit makes RTC_CTRL_REG volatile, but > + * we don't use that feature. It's better to cache. > + * - It's unlikely we care that RK808_DEVCTRL_REG is volatile since > + * bits are cleared in case when we shutoff anyway, but better safe. > + */ > + > + switch (reg) { > + case RK808_SECONDS_REG ... RK808_WEEKS_REG: > + case RK808_RTC_STATUS_REG: > + case RK808_VB_MON_REG: > + case RK808_THERMAL_REG: > + case RK808_DCDC_UV_STS_REG: > + case RK808_LDO_UV_STS_REG: > + case RK808_DCDC_PG_REG: > + case RK808_LDO_PG_REG: > + case RK808_DEVCTRL_REG: > + case RK808_INT_STS_REG1: > + case RK808_INT_STS_REG2: > + return true; > + } > + > + return false; > +} > + > static const struct regmap_config rk808_regmap_config = { > .reg_bits = 8, > .val_bits = 8, > .max_register = RK808_IO_POL_REG, > + .cache_type = REGCACHE_RBTREE, > + .volatile_reg = rk808_is_volatile_reg, > }; > > static struct resource rtc_resources[] = { Reviewed-by: Chris Zhong