From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH v2 05/11] ARM: dt: tegra30: Add device node for APB MISC Date: Thu, 03 Jan 2013 21:00:35 -0700 Message-ID: <50E653E3.5060901@wwwdotorg.org> References: <1356619644-18565-1-git-send-email-pgaikwad@nvidia.com> <1356619644-18565-6-git-send-email-pgaikwad@nvidia.com> <50E4AE19.1060503@wwwdotorg.org> <50E520FC.4070805@nvidia.com> <50E5ADA6.1070904@wwwdotorg.org> <50E634D0.6080702@nvidia.com> <50E6470E.8090206@wwwdotorg.org> <50E64B18.8060806@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <50E64B18.8060806@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Prashant Gaikwad Cc: "mturquette@linaro.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-tegra@vger.kernel.org" List-Id: linux-tegra@vger.kernel.org On 01/03/2013 08:23 PM, Prashant Gaikwad wrote: > On Friday 04 January 2013 08:35 AM, Stephen Warren wrote: >> On 01/03/2013 06:48 PM, Prashant Gaikwad wrote: >>> On Thursday 03 January 2013 09:41 PM, Stephen Warren wrote: ... >>>> OK. It sounds like we need a true APB MISC driver then, to abstract the >>>> differences; the clock driver really shouldn't be touching the APB MISC >>>> registers in all likelihood, unless a subset of the sections you >>>> mention >>>> above are truly dedicated to clock functionality. >>> >>> I don't think it is a good idea to create a driver for APB MISC, all >>> registers are used by different drivers. >> >> Well, it's even worse to have a bunch of other drivers randomly trample >> on a set of registers they don't own. >> >>> Only chip id revision registers are used in clock driver. >> There are already global variables exposed by the Tegra fuse driver; can >> you just read those? > > It is not about variables or some value, we have to read some apb > register to flush the write operation in apb bus before we disable > peripheral clock. > We are using chip id revision register for this purpose. Ah. That's definitely not something the clock driver should be doing directly. It's probably OK to add a custom Tegra-specific function to some file in arch/arm/mach-tegra to implement this. Even better would be a full bus driver for the APB bus, but that's probably too much bloat for now.