Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751500Ab3IJL25 (ORCPT ); Tue, 10 Sep 2013 07:28:57 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:14163 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751069Ab3IJL2z (ORCPT ); Tue, 10 Sep 2013 07:28:55 -0400 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Tue, 10 Sep 2013 04:28:55 -0700 Message-ID: <522F02A4.7060702@nvidia.com> Date: Tue, 10 Sep 2013 19:29:40 +0800 From: Wei Ni User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130804 Thunderbird/17.0.8 MIME-Version: 1.0 To: Mark Brown CC: Guenter Roeck , "khali@linux-fr.org" , "swarren@wwwdotorg.org" , "lm-sensors@lm-sensors.org" , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v3 1/2] hwmon: (lm90) Add power control References: <20130909111242.GW29403@sirena.org.uk> <522DB253.6000707@roeck-us.net> <20130909135022.GZ29403@sirena.org.uk> <20130909155043.GA18975@roeck-us.net> <20130909160237.GR29403@sirena.org.uk> <20130909161735.GC18975@roeck-us.net> <20130909203910.GV29403@sirena.org.uk> <522E9A85.9050803@nvidia.com> <522EA51C.90706@roeck-us.net> <522EB0AF.9030708@nvidia.com> <20130910101359.GX29403@sirena.org.uk> In-Reply-To: <20130910101359.GX29403@sirena.org.uk> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1341 Lines: 35 On 09/10/2013 06:13 PM, Mark Brown wrote: > * PGP Signed by an unknown key > > On Tue, Sep 10, 2013 at 01:39:59PM +0800, Wei Ni wrote: > >> I think the device need time to wait stable after power on, but it's >> difficult to get an exact delay value, and this delay may also relate >> with platform design, so how about to add a optional property in the DT >> node, such as "power-on-delay-ms" ? > > This is something you should *really* be able to get from the datasheet > for the part - this sort of stuff has to be documented for hardware to > be used robustly. It seems entirely possible that you are working > around an issue with the regulator driver you are using not correctly > providing its ramp time here. On my platform, it use palmas-regulator.c, ldo6 for this lm90 power rail. I checked this driver, it will handle ramp_delay except LDOx. Since I'm not familiar with this palmas device and driver, so do you mean I can set regulator-ramp-delay property in the DT for ldo6, but I really don't know what value should I set :( Thanks. Wei. > > * Unknown Key > * 0x7EA229BD > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/