From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754644AbdECSxK (ORCPT ); Wed, 3 May 2017 14:53:10 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:38560 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751564AbdECSxE (ORCPT ); Wed, 3 May 2017 14:53:04 -0400 Date: Wed, 3 May 2017 19:52:51 +0100 From: Russell King - ARM Linux To: Keerthy Cc: sboyd@codeaurora.org, t-kristo@ti.com, mturquette@baylibre.com, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, Russ Dill Subject: Re: [PATCH] clk: Add functions to save and restore clock/dpll context en-masse Message-ID: <20170503185251.GR23750@n2100.armlinux.org.uk> References: <1492492369-19662-1-git-send-email-j-keerthy@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1492492369-19662-1-git-send-email-j-keerthy@ti.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 18, 2017 at 10:42:49AM +0530, Keerthy wrote: > From: Russ Dill > > The clock/dpll registers are in the WKUP power domain. Under both RTC-only > suspend and hibernation, these registers are lost. Hence save/restore > them accordingly. This looks like a huge hammer, and I think this will cause problems for some systems, especially where some clocks are on remote devices which need to be controlled via I2C buses. The generic part walks all root clocks in the system, and all children of those clocks. If we have clocks on an I2C device, then we could very well end up with a circular dependency - the I2C controller needs its clocks restored in order for control of the clocks on the I2C device to be accessible. So, I think this needs more thought - clocks are not just about core SoC clocks - and cracking this nut with such a big hammer is likely to cause regressions all over the place. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.