From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH 1/4] ARM: OMAP2+: omap_hwmod: Introduce ti,no-init dt property Date: Thu, 5 Mar 2015 16:41:57 -0800 Message-ID: <20150306004157.GI13520@atomide.com> References: <1425561211-31003-1-git-send-email-d-gerlach@ti.com> <1425561211-31003-2-git-send-email-d-gerlach@ti.com> <20150305184952.GF13520@atomide.com> <54F8B2C7.7060202@ti.com> <20150305201713.GH13520@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20150305201713.GH13520@atomide.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Dave Gerlach Cc: devicetree@vger.kernel.org, Paul Walmsley , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, KEERTHY List-Id: linux-omap@vger.kernel.org * Tony Lindgren [150305 12:24]: > * Dave Gerlach [150305 11:53]: > > On 03/05/2015 12:49 PM, Tony Lindgren wrote: > > > * Paul Walmsley [150305 10:16]: > > >> On Thu, 5 Mar 2015, Dave Gerlach wrote: > > >> > > >>> Introduce a dt property, ti,no-init, that prevents hwmod initialization. > > >>> Even if a dt node is marked as disabled, hwmod still at least enables > > >>> the hwmod and programs the sysconfig before attempting to idle it at > > >>> boot. If an IP has been disabled by the hardware configuration on a > > >>> platform, this will cause a hang due to writing to inactive registers. > > >>> This property prevents that from happening by marking the hwmod as > > >>> _HWMOD_STATE_DISABLED during init. > > >> > > >> I'm kind of wondering if hwmod should even touch a device if it's marked > > >> as disabled in the DT. Tony, what do you think? > > > > > > Well nothing happens if a device is status = "disabled". No dev entry > > > gets created for it at all and hwmod won't have any data for the device > > > populated. The only way hwmod code could see that device if the device > > > gets it's data from the legacy omap_hwmod_*_data.c instead of DT. > > > > > > > We still need this for the sysconfig programming, correct? hwmod programs that > > regardless of dt status and then idles the IP, > > Well hwmod does not even know about the IP IO addresses if it's marked > with status = "disabled".. Which IP are you having problems with? > > > which is why I needed the ti,no-init for the epos evm. It isn't just a > > matter of we shouldnt write to it because we don't want to use it; we > > can't write to it because the module is held off so it causes an > > external abort if we do. > > Well hard to say not knowing which module this is.. Pretty much all > the modules have drivers and the driver just does pm_runtime_get() > on it? Heh OK this thread is about the RTC driver, so I assume that's the problem :) So if you set the rtc to status = "disabled" how can the hwmod code do anything as AFAIK it won't even get the rtc IO address? Or am I missing something here? Regards, Tony