From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Turquette Subject: Re: [RFC PATCH] dt: describe base reset signal binding Date: Wed, 31 Oct 2012 03:32:21 -0700 Message-ID: <20121031103221.18780.43096@nucleus> References: <1351028756-22309-1-git-send-email-swarren@wwwdotorg.org> <20121029183233.18780.11964@nucleus> <5090161D.2030702@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5090161D.2030702-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Stephen Warren Cc: "Rafael J. Wysocki" , Stephen Warren , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Rob Herring , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org Quoting Stephen Warren (2012-10-30 11:02:05) > On 10/29/2012 12:32 PM, Mike Turquette wrote: > > Quoting Stephen Warren (2012-10-23 14:45:56) > >> What do people think of this? Does it sound like a good idea to go ahead > >> with a reset subsystem? Should we simply add a new API to the common clock > >> subsystem instead (and assume that reset and clock domains match 1:1). > >> Should this be implemented as part of the generic power management domains; > >> see include/linux/pm_domain.h instead? > >> > > > > Hi Stephen, > > > > I'm not sure a "reset subsystem" is necessary, but I also do not like > > using clocks as the keys for IP reset. > > I'm not sure what you're suggesting as an alternative to a reset > subsystem (or API if you want something that sounds smaller!) :-) > My point was that I do not know if a new subsystem is necessary or not. Your suggestion to "simply add a new API to the common clock subsystem" is an example of an alternative to a whole new subsystem. However I instinctively feel that the clock api is not the right place for reseting devices. > > I think it is more common to map IPs to struct device, no? > > It is indeed probably common that there's a 1:1 mapping between IP > blocks and struct device. However, I'm sure there are plenty of > counter-examples; IP blocks with multiple reset domains (hence struct > devices that encompass multiple reset domains, or reset domains that > encompass multiple struct devices), just as there are many examples of > non-1:1 mappings between struct device and struct clk. > In OMAP code we handle IP resets through the hwmod code and I prefer that IP-centric approach to associating IP resets with a clock node. Perhaps the hwmod approach could serve as inspiration for a new generic way to reset modules. > Even ignoring that, we'd still need to API say device_reset(struct > device *dev) or device_reset(struct device *dev, const char *conid) > wouldn't we? That's really all I meant by a reset subsystem. > Of course. The api must exist. > An alternative here would be to simply move Tegra's > tegra_periph_reset_{de,}assert() function prototypes into a header in > include/linux rather than mach-tegra/include/mach. However, I imagine at > least some other SoC needs a similar API, so a common API might be useful? I also agree. I think that there was simply some confusion about how I responded. To reiterate, I'm not sure whether a new subsystem should be created or if the API can find a home in some existing subsystem, but I don't think the clock framework is the right place for it. Regards, Mike