Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752248AbbGQLRP (ORCPT ); Fri, 17 Jul 2015 07:17:15 -0400 Received: from foss.arm.com ([217.140.101.70]:48415 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750795AbbGQLRN (ORCPT ); Fri, 17 Jul 2015 07:17:13 -0400 Message-ID: <55A8E434.2010709@arm.com> Date: Fri, 17 Jul 2015 12:17:08 +0100 From: Sudeep Holla User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Stephen Boyd CC: Sudeep Holla , "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" , "linux-clk@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Liviu Dudau , Lorenzo Pieralisi , "Jon Medhurst (Tixy)" , Arnd Bergmann , Kevin Hilman , Olof Johansson , Mike Turquette Subject: Re: [PATCH v4 3/8] clk: add support for clocks provided by SCP(System Control Processor) References: <1433760002-24120-1-git-send-email-sudeep.holla@arm.com> <1433760002-24120-4-git-send-email-sudeep.holla@arm.com> <20150702172310.GF4301@codeaurora.org> <5596A1B6.8020307@arm.com> <559ADC94.4080505@codeaurora.org> <559BF858.1020301@arm.com> <20150708014606.GH30412@codeaurora.org> <55A7D79B.3080305@arm.com> <20150716193114.GA17952@codeaurora.org> In-Reply-To: <20150716193114.GA17952@codeaurora.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3392 Lines: 81 On 16/07/15 20:31, Stephen Boyd wrote: > On 07/16, Sudeep Holla wrote: >> On 08/07/15 02:46, Stephen Boyd wrote: >>> >>> Yes struct clk would have min/max, and struct clk_core would have >>> min/max. Then some sort of provider API (or possibly even >>> clk_init_data) would take the min/max fields and copy them over >>> to struct clk_core. Then during set_rate operations we would >>> aggregate the constraints from struct clk like we already do and >>> add in the constrains in struct clk_core. >>> >>> One downside to adding new fields to clk_init_data is that there >>> are drivers out there that aren't initializing that structure to >>> 0, and they're putting it on the stack, so stack junk can come >>> through. Furthermore, min/max would mean that every driver needs >>> to specify some large number for max or we have to special case >>> min == max == 0 and ignore it. Somehow it needs to be opt-in. If >>> we want to go down the clk_init_data route then perhaps we need >>> some sort of rate_constraint struct pointer in there that drivers >>> can optionally setup. >>> >>> struct clk_rate_constraint { >>> unsigned long min; >>> unsigned long max; >>> }; >>> >>> struct clk_init_data { >>> ... >>> struct clk_rate_constraint *rate_constraint; >>> }; >>> >>> I haven't thought it through completely, but I can probably write >>> up some patch tomorrow after I sleep on it. >>> >> >> I am hoping to get this series for v4.3. In order to avoid using >> consumer API, I can revert back to the min,max check I had in the >> round_rate earlier if that's fine with you ? Let me know so that I can >> post the next version based on that. All the other comments are already >> addressed. > > Ok. I'm fine with the consumer API being used, but it would be > nice if we didn't have to do so. Try out the patch below, > hopefully it's good enough for your purposes. It may need to be > more robust, and we may still want to use the init_data structure > to avoid races with providers and consumers, but we can leave > that for later after sweeping all the structure users. > Agreed, I would avoid using clk consumer API or use it with TODO so that I remember to remove it soon. Anyways, thanks for the patch, I tested it and works fine to me. You can add Tested-by if you decide to push it. >> >> Also since this series depends on SCPI, I was thinking to get it merged >> via ARM-SoC, but that might conflict with the round_rate prototype >> change. Do do plan to share a stable base with arm-soc guys or you >> expect all the changes to be contained in clk tree ? >> > > We can share a stable branch for the determine_rate change with > arm-soc. We already have it on a separate branch but haven't > published it so far because nobody has asked. > determine_rate change shouldn't affect SCPI clock driver but I remember seeing round_rate change too on the list which returns value using the argument from Boris. Is that planned for v4.3 ? I would need the stable branch from this clk_hw_set_rate_range if you decide to push. Let me know your preferences. I will post the updated version of the patch accordingly. Regards, Sudeep -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/