From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter De Schrijver Subject: Re: [v2 1/4] ARM: tegra20: create a DT header defining CLK IDs Date: Thu, 21 Feb 2013 14:25:36 +0200 Message-ID: <20130221122536.GJ23234@tbergstrom-lnx.Nvidia.com> References: <1360868369-20093-1-git-send-email-hdoyu@nvidia.com> <1360868369-20093-2-git-send-email-hdoyu@nvidia.com> <511D45E0.1080105@wwwdotorg.org> <20130215092407.GO3073@tbergstrom-lnx.Nvidia.com> <511E6639.1090909@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <511E6639.1090909@wwwdotorg.org> Sender: linux-doc-owner@vger.kernel.org To: Stephen Warren Cc: Hiroshi Doyu , Russell King , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Rob Herring , "linux-tegra@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" List-Id: devicetree@vger.kernel.org On Fri, Feb 15, 2013 at 05:45:45PM +0100, Stephen Warren wrote: ... > > I would suggest removing this clock. It's not actually implemented in the CCF > > and rather useless. If you would gate the CPU clock from the CPU by writing to > > this register, how would you ungate it? :) Note that this would gate the clock > > to all CPUs. > > (Note that my comment was re: all clocks, not just that one clock) > > Can't the PMC or flow-controller ungate the clock based on some event? I don't think the flow-controller controls this gate. The usual way of clockgating a core is to execute a WFI instruction. That will trigger clockgating the core, unless the flow-controller has been programmed to do something else. The flow-controller will ungate the clock when there is an interrupt. > Either way, that clock definition exists in HW, right? So I don't think > there's actually any harm in including the definition in the binding > even if we never implement/use it. The clock definition seems to exist in HW yes, the corresponding resetbit however is marked as 'reserved' in the Tegra114 documentation. Cheers, Peter.