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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3565C433F5 for ; Wed, 4 May 2022 02:22:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343964AbiEDC0F (ORCPT ); Tue, 3 May 2022 22:26:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343912AbiEDC0E (ORCPT ); Tue, 3 May 2022 22:26:04 -0400 Received: from alexa-out-sd-01.qualcomm.com (alexa-out-sd-01.qualcomm.com [199.106.114.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9ADC222BDD; Tue, 3 May 2022 19:22:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1651630950; x=1683166950; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=qlXIY1CWPzwHXGxBw+qIB1k+fX6YOx/8ySBx/gBpvGA=; b=zEKoJAvUa1UwY/DBDAm05zTs1rdGRsYOgiCnWgLCz/ozuR7L0hUMMhKg Hngdk9VOuGoDJpnvUqnsBWYHiUeMgDajV1COVttF5/uVQ4+SBoQ4oY/r4 Eq+er7l1C/sx8Qzhy8Y4YHwpmRNRnCUYfQS3P8TVPO2toHW+EKR/58DMV g=; Received: from unknown (HELO ironmsg05-sd.qualcomm.com) ([10.53.140.145]) by alexa-out-sd-01.qualcomm.com with ESMTP; 03 May 2022 19:22:30 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg05-sd.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 May 2022 19:22:30 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Tue, 3 May 2022 19:22:30 -0700 Received: from [10.110.46.161] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Tue, 3 May 2022 19:22:29 -0700 Message-ID: Date: Tue, 3 May 2022 19:22:28 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH 5/5] bus: mhi: host: Remove redundant dma_wmb() before ctx wp update Content-Language: en-US To: Manivannan Sadhasivam , CC: , , , References: <20220502104144.91806-1-manivannan.sadhasivam@linaro.org> <20220502104144.91806-6-manivannan.sadhasivam@linaro.org> From: Hemant Kumar In-Reply-To: <20220502104144.91806-6-manivannan.sadhasivam@linaro.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 5/2/2022 3:41 AM, Manivannan Sadhasivam wrote: > The endpoint device will only read the context wp when the host rings > the doorbell. And moreover the doorbell write is using writel(). This > guarantess that the prior writes will be completed before ringing > doorbell. > > So there is no need of an additional dma_wmb() to order the coherent > memory writes w.r.t each other. Even if the writes gets reordered, it > won't affect the endpoint device. > > Cc: Loic Poulain > Signed-off-by: Manivannan Sadhasivam > Reviewed by: Hemant Kumar >