From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH V2 2/2] ARM: dts: DRA7: Add node for RTC Date: Mon, 14 Jul 2014 23:59:28 -0700 Message-ID: <20140715065928.GK20068@atomide.com> References: <53BD0C43.1090002@ti.com> <20140709100914.GL28884@atomide.com> <53BD1AF8.2060609@ti.com> <20140709105055.GP28884@atomide.com> <53BD1FC3.6050500@ti.com> <20140709110051.GQ28884@atomide.com> <53BD2249.2080808@ti.com> <53C3ED02.7020206@ti.com> <20140714162324.GF20068@atomide.com> <53C4A8F5.2000302@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <53C4A8F5.2000302@ti.com> Sender: linux-omap-owner@vger.kernel.org To: Lokesh Vutla Cc: Keerthy , paul@pwsan.com, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, rnayak@ti.com, devicetree@vger.kernel.org, nm@ti.com, j-keerthy@ti.com, nsekhar@ti.com List-Id: devicetree@vger.kernel.org * Lokesh Vutla [140714 21:09]: > On Monday 14 July 2014 09:53 PM, Tony Lindgren wrote: > > * Lokesh Vutla [140714 07:47]: > >> > >> In my experiments I observed that when RTC regulator is switched > >> off and switched on, there is an abort while accessing RTC registers. > > > > Right, then you know you have the right regulator :) > > Once we switch it off it is expected, but then if it is *switched on* > it is expected that we should be able to access registers. Here there > is an abort accessing these registers. Most likely you need to also reconfigure the registers or re-enable the clock or reset it at the interconnect too. > >> After discussing with hardware team, it is confirmed that this > >> LDO9 regulator powering RTC cannot be turned off when > >> SoC is active and expected to be always on. > > > > Hmm but sounds like you already proved it can be idled? So > > the regulator really should be managed by the driver? > > Actually I adapted the driver to support a power regulator. > Then I observed that if rtc is loaded as a module there is > an abort( which is happening because the regulator is disabled > once and re-enabled). So when we checked with the hardware team, > they confirmed that ldo9 should not be disabled. Hmm so how is it enabled initially then? To me it sounds like very standard stuff to reinitialize a driver for any omap device when waking from suspend or returning from off-idle. If the RTC device cannot be reset, idled and re-initialized properly, there's something wrong with the RTC driver, clocks, regulators, or hwmod data for that device. Regards, Tony