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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 5A87AC4338F for ; Tue, 27 Jul 2021 10:35:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 46F6F60FA0 for ; Tue, 27 Jul 2021 10:35:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236341AbhG0Kfk (ORCPT ); Tue, 27 Jul 2021 06:35:40 -0400 Received: from so254-9.mailgun.net ([198.61.254.9]:59388 "EHLO so254-9.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236188AbhG0Kfk (ORCPT ); Tue, 27 Jul 2021 06:35:40 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1627382140; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=jcDIGTlNdb13VAIbuMs/ke9zWyHAfziW4NuYUouZlG8=; b=ErDisCzF92DoTZUOiP2cLU+ry77wJmjovEKIrx+OqcJcnYp0q6vcsrsj4eEEcy0xPiNFRRUF VXyWIS0LWo6r3+jATIsaMqSu/a9rhnU8Mgonh5Z3uENEPc1iB8b02welNrVo2Q91TLudl1+1 SppgqdNIAFqcRB5qL+gx3sXAB6g= X-Mailgun-Sending-Ip: 198.61.254.9 X-Mailgun-Sid: WyI1MzIzYiIsICJsaW51eC1hcm0tbXNtQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n06.prod.us-east-1.postgun.com with SMTP id 60ffe162290ea35ee6f2a43f (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 27 Jul 2021 10:35:14 GMT Sender: saiprakash.ranjan=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 6E84AC4323A; Tue, 27 Jul 2021 10:35:13 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: saiprakash.ranjan) by smtp.codeaurora.org (Postfix) with ESMTPSA id A5083C433D3; Tue, 27 Jul 2021 10:35:12 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 27 Jul 2021 16:05:12 +0530 From: Sai Prakash Ranjan To: Robin Murphy Cc: Will Deacon , Joerg Roedel , Rajendra Nayak , Taniya Das , srimuc , linux-arm-msm@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] iommu/arm-smmu: Add clk_bulk_{prepare/unprepare} to system pm callbacks In-Reply-To: References: <20210727093322.13202-1-saiprakash.ranjan@codeaurora.org> <955a3034-f7e7-f8f9-4abd-b65efbfbb404@arm.com> Message-ID: X-Sender: saiprakash.ranjan@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Hi Robin, On 2021-07-27 16:03, Robin Murphy wrote: > On 2021-07-27 11:25, Robin Murphy wrote: >> On 2021-07-27 10:33, Sai Prakash Ranjan wrote: >>> Some clocks for SMMU can have parent as XO such as >>> gpu_cc_hub_cx_int_clk >>> of GPU SMMU in QTI SC7280 SoC and in order to enter deep sleep states >>> in >>> such cases, we would need to drop the XO clock vote in unprepare call >>> and >>> this unprepare callback for XO is in RPMh (Resource Power >>> Manager-Hardened) >>> clock driver which controls RPMh managed clock resources for new QTI >>> SoCs >>> and is a blocking call. >>> >>> Given we cannot have a sleeping calls such as clk_bulk_prepare() and >>> clk_bulk_unprepare() in arm-smmu runtime pm callbacks since the iommu >>> operations like map and unmap can be in atomic context and are in >>> fast >>> path, add this prepare and unprepare call to drop the XO vote only >>> for >>> system pm callbacks since it is not a fast path and we expect the >>> system >>> to enter deep sleep states with system pm as opposed to runtime pm. >>> >>> This is a similar sequence of clock requests (prepare,enable and >>> disable,unprepare) in arm-smmu probe and remove. >> >> Nope. We call arm_smmu_rpm_get(), which may resume the device, from >> atomic contexts. clk_prepare() may sleep. This doesn't work. > > Urgh, or maybe I skimmed the commit message too lightly *and* managed > to totally misread the patch, sorry :( > > I'll wake up some more and try again later... > No worries, we took our time looking through that many times before posting this :) Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation