From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 524FBC43387 for ; Thu, 17 Jan 2019 11:19:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 21FA22054F for ; Thu, 17 Jan 2019 11:19:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="I6mXoR1P"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="PvnaG38v" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727301AbfAQLTx (ORCPT ); Thu, 17 Jan 2019 06:19:53 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:35586 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726826AbfAQLTx (ORCPT ); Thu, 17 Jan 2019 06:19:53 -0500 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 7ED3260807; Thu, 17 Jan 2019 11:19:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1547723992; bh=BCZR8UQDjYKKai5NpFpjklSk3mT5UK7jcQhOw69F3T4=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=I6mXoR1Py35p+W8awHHCCTQ5O3N3x+hJ85aAFLdWbaki6d9UOzgn77Z34TT9gQxCM ir8bwOGvZIQ1w2h9laY5cAC0SY8DLYRP84aZ0+EHGAry4gy3R/Ac+oKDyMfBSbVq/4 TMkyXSMKnudlnAGBlXDegwY5mCwZozbu8my3VsPg= Received: from [192.168.225.247] (unknown [49.33.245.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: tdas@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id D0829606E1; Thu, 17 Jan 2019 11:19:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1547723991; bh=BCZR8UQDjYKKai5NpFpjklSk3mT5UK7jcQhOw69F3T4=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=PvnaG38vg/6+ek02L4IMa++e5aBViaSvZFpYNbGnpQdtDsiWjg6U9JAUHAdWey+8u R/A//gAWyh6XJtQvLJ4glViqXb5ZGZ26lClXYpBHeVX0LHlfi0H4NhfEjJFMIu6wDb /gICebHf3rzt2KhUm1fcF8/14wrsMJWZ9rcI4Cs0= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org D0829606E1 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=tdas@codeaurora.org Subject: Re: [PATCH v1] clk: qcom: lpass: Add CLK_IGNORE_UNUSED for lpass clocks To: Stephen Boyd , Michael Turquette Cc: Andy Gross , David Brown , Rajendra Nayak , linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org References: <1545306385-31240-1-git-send-email-tdas@codeaurora.org> <154533989563.79149.10213938035592547726@swboyd.mtv.corp.google.com> <154689507747.15366.6553307032295093169@swboyd.mtv.corp.google.com> <154750471090.169631.5712250327468594228@swboyd.mtv.corp.google.com> From: Taniya Das Message-ID: <6ad2f27c-0afc-af6a-8198-679a88dcc2f9@codeaurora.org> Date: Thu, 17 Jan 2019 16:49:22 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <154750471090.169631.5712250327468594228@swboyd.mtv.corp.google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org On 1/15/2019 3:55 AM, Stephen Boyd wrote: > Quoting Taniya Das (2019-01-13 22:12:39) >> >> >> On 1/8/2019 2:34 AM, Stephen Boyd wrote: >>> >>> As far as I know, I'm not suggesting the use of CLK_IS_CRITICAL here. >>> But removing CLK_IS_CRITICAL and relying on some random bootloader >>> behavior also looks wrong. Can you clarify what's going on? >>> >> >> To enable LPASS clocks the requirement is to enable the GCC_LPASS_SWAY >> clock. >> 1) If the LPASS drivers are enabled/probed before the clock late init >> the client would take care to maintain the dependency to enable the >> GCC_LPASS_SWAY clock before enabling the LPASS clocks. >> >> 2) There could be a condition where the LPASS drivers would probe/init >> later the clock late_init. When the clock_late_init would try to access >> the LPASS clocks, since we cannot maintain the dependency this access >> would fail. To avoid this the earlier patch has made the GCC_LPASS_SWAY >> clock as CRITICAL. >> >> 3) Marking the GCC_LPASS_SWAY clock as CRITICAL has a issue, in the case >> where the LPASS subsystem would be restarted due to some critical >> failure on LPASS. Toggling the restart register of LPASS would clear the >> hardware state of this clock and thus the next access of the LPASS >> clocks would result in failure of the system. >> >> 4) To avoid issues happening in (2) and (3) all the LPASS clocks chould >> be safely marked as CLK_IGNORE_UNUSED. And lpass drivers would take care >> of the dependency to enable the required clocks. >> > > Ok, so why can't we enable/disable the lpass sway clk in the > prepare/unprepare phase of the lpass clk driver paths? Or why can't we > forcibly enable this lpass sway clk after the reset is deasserted? Which > clk controller is the reset part of? GCC or LPASS? It is part of Always On Subsystem. > > It still sounds like the LPASS clk driver isn't handling dependencies it > has on accessing registers, but maybe we can get away with not handling > the dependency still if we make the reset "do the right thing" and turn > the clk back on so it stays "critical". > This is a reset from hardware and it does not bring back the clock to the previous state and so we can not mark it "critical". I would submit the next series with comments updated. Please let me know in case you have any comments. -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation. --