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=-6.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 5D99FC433DB for ; Tue, 12 Jan 2021 10:11:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0125522CBE for ; Tue, 12 Jan 2021 10:11:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390336AbhALKLn (ORCPT ); Tue, 12 Jan 2021 05:11:43 -0500 Received: from mail.kernel.org ([198.145.29.99]:46918 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389927AbhALKLn (ORCPT ); Tue, 12 Jan 2021 05:11:43 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id C3EF022CBE; Tue, 12 Jan 2021 10:11:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1610446262; bh=SJdJsLW3E8Nwahw4Ky16T74RFBuZ491EnoseBaUMOIU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pqy1p9OhYmPgyJKboHZC2ehmLQo/7Rdm9ZtwZJUJJh1Capla4PRjxfOAXx8uxpOD6 6pcFdlWXd8HXcxBJparAK4h9EhrRU7bZLGqn3M8cI5Mq7x7JKHiPa9TlxG1R4pwyGK t7JX9IpHQpMTAkJhaFelUI7pqcvTqaqM/dQUMDutwBvq5I+2od8uBiEgoA+nUi69qC 3WxsGyy5foUF6MFAvu8fH47zbxKwwYBd2gJ6HZ1q9tGxW9x/4KC2jCG1yrWM7JXhwg GFmcZvUAhEF7kMPIwuAyrtaHDSg5aPckswS6DMfSIjwaidJL9d3Jun0jDOHZg8QjKF 8OF1U9zLGvCwQ== Date: Tue, 12 Jan 2021 15:40:56 +0530 From: Vinod Koul To: mdalam@codeaurora.org Cc: corbet@lwn.net, agross@kernel.org, bjorn.andersson@linaro.org, dan.j.williams@intel.com, dmaengine@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, sricharan@codeaurora.org, mdalam=codeaurora.org@codeaurora.org Subject: Re: [PATCH] dmaengine: qcom: bam_dma: Add LOCK and UNLOCK flag bit support Message-ID: <20210112101056.GI2771@vkoul-mobl> References: <1608215842-15381-1-git-send-email-mdalam@codeaurora.org> <20201221092355.GA3323@vkoul-mobl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 12-01-21, 15:01, mdalam@codeaurora.org wrote: > On 2020-12-21 23:03, mdalam@codeaurora.org wrote: > > On 2020-12-21 14:53, Vinod Koul wrote: > > > Hello, > > > > > > On 17-12-20, 20:07, Md Sadre Alam wrote: > > > > This change will add support for LOCK & UNLOCK flag bit support > > > > on CMD descriptor. > > > > > > > > If DMA_PREP_LOCK flag passed in prep_slave_sg then requester of this > > > > transaction wanted to lock the DMA controller for this transaction so > > > > BAM driver should set LOCK bit for the HW descriptor. > > > > > > > > If DMA_PREP_UNLOCK flag passed in prep_slave_sg then requester > > > > of this > > > > transaction wanted to unlock the DMA controller.so BAM driver > > > > should set > > > > UNLOCK bit for the HW descriptor. > > > > > > Can you explain why would we need to first lock and then unlock..? How > > > would this be used in real world. > > > > > > I have read a bit of documentation but is unclear to me. Also should > > > this be exposed as an API to users, sounds like internal to driver..? > > > > > > > IPQ5018 SoC having only one Crypto Hardware Engine. This Crypto Hardware > > Engine > > will be shared between A53 core & ubi32 core. There is two separate > > driver dedicated > > to A53 core and ubi32 core. So to use Crypto Hardware Engine > > parallelly for encryption/description > > we need bam locking mechanism. if one driver will submit the request > > for encryption/description > > to Crypto then first it has to set LOCK flag bit on command descriptor > > so that other pipes will > > get locked. > > > > The Pipe Locking/Unlocking will be only on command-descriptor. Upon > > encountering a command descriptor Can you explain what is a cmd descriptor? > > with LOCK bit set, The BAM will lock all other pipes not related to > > the current pipe group, and keep > > handling the current pipe only until it sees the UNLOCK set then it > > will release all locked pipes. > > locked pipe will not fetch new descriptors even if it got event/events > > adding more descriptors for > > this pipe (locked pipe). > > > > No need to expose as an API to user because its internal to driver, so > > while preparing command descriptor > > just we have to update the LOCK/UNLOCK flag. So IIUC, no api right? it would be internal to driver..? -- ~Vinod