From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755484AbbB0Vtt (ORCPT ); Fri, 27 Feb 2015 16:49:49 -0500 Received: from mail-wg0-f47.google.com ([74.125.82.47]:46838 "EHLO mail-wg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755007AbbB0Vtr (ORCPT ); Fri, 27 Feb 2015 16:49:47 -0500 Date: Fri, 27 Feb 2015 21:49:41 +0000 From: Lee Jones To: Robert Jarzmik Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mturquette@linaro.org, sboyd@codeaurora.org, kernel@stlinux.com, devicetree@vger.kernel.org Subject: Re: [PATCH v3 0/4] clk: st: New always-on clock domain Message-ID: <20150227214941.GB12821@x1> References: <1424799222-9301-1-git-send-email-lee.jones@linaro.org> <87385r3uk9.fsf@free.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87385r3uk9.fsf@free.fr> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 27 Feb 2015, Robert Jarzmik wrote: > Lee Jones writes: > > > v2 => v3: > > - Ensure DT actually reflects h/w > > - i.e. Nodes should not contain a mishmash of different IP > > blocks, but should identify related h/w. In the current > > example we use interconnects > > - Change naming from clkdomain to clk-always-on > > - Place "do not abuse" warning in documentation > > > > v1 => v2: > > - Turned the ST specific driver into a generic one > > > > Hardware can have a bunch of clocks which must not be turned off. > > If drivers a) fail to obtain a reference to any of these or b) give > > up a previously obtained reference during suspend, the common clk > > framework will attempt to turn them off and the hardware will > > subsequently die. The only way to recover from this failure is to > > restart. > > > > To avoid either of these two scenarios from catastrophically > > disabling the running system we have implemented a clock domain > > where clocks are consumed and references are taken, thus preventing > > them from being shut down by the framework. > > Hi Lee, > > I wonder why there is a need for a new clock when CLK_IGNORE_UNUSED does > exist. What is the usecase that is covered by this patchset which is not used by > CLK_IGNORE_UNUSED clock flag ? > > And if that reason exists, I'd like to find it in the commit message. The problem is applying that flag in a generic way. However, I guess you haven't seen this [1] yet? [1] https://lkml.org/lkml/2015/2/27/548 -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog