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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 8CC0CC433E0 for ; Tue, 5 Jan 2021 17:36:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B7C822D01 for ; Tue, 5 Jan 2021 17:36:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729919AbhAERgS (ORCPT ); Tue, 5 Jan 2021 12:36:18 -0500 Received: from foss.arm.com ([217.140.110.172]:58086 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725838AbhAERgR (ORCPT ); Tue, 5 Jan 2021 12:36:17 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7D5A71063; Tue, 5 Jan 2021 09:35:31 -0800 (PST) Received: from bogus (unknown [10.57.35.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CC94A3F66E; Tue, 5 Jan 2021 09:35:29 -0800 (PST) Date: Tue, 5 Jan 2021 17:35:26 +0000 From: Sudeep Holla To: Florian Fainelli Cc: Jim Quinlan , Sudeep Holla , bcm-kernel-feedback-list@broadcom.com, james.quinlan@broadcom.com, "open list:SYSTEM CONTROL & POWER/MANAGEMENT INTERFACE Mes..." , open list Subject: Re: [PATCH v4 2/2] firmware: arm_scmi: Augment SMC/HVC to allow optional interrupt Message-ID: <20210105173526.yvjh2bxnofjzmc6n@bogus> References: <20201222145603.40192-1-jim2101024@gmail.com> <20201222145603.40192-3-jim2101024@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20171215 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 22, 2020 at 07:37:22PM -0800, Florian Fainelli wrote: > > > On 12/22/2020 6:56 AM, Jim Quinlan wrote: > > The SMC/HVC SCMI transport is modified to allow the completion of an SCMI > > message to be indicated by an interrupt rather than the return of the smc > > call. This accommodates the existing behavior of the BrcmSTB SCMI > > "platform" whose SW is already out in the field and cannot be changed. > > > > Signed-off-by: Jim Quinlan > > This looks good to me, just one question below: > > [snip] > > > @@ -111,6 +145,8 @@ static int smc_send_message(struct scmi_chan_info *cinfo, > > shmem_tx_prepare(scmi_info->shmem, xfer); > > > > arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res); > > + if (scmi_info->irq) > > + wait_for_completion(&scmi_info->tx_complete); > > Do we need this to have a preceding call to reinit_completion()? It does > not look like this is going to make any practical difference but there > are drivers doing that for correctness. Why do you think that might not cause any issue ? After first message is completed and ISR is executed, the completion flag remains done for ever. So practically 2nd message onwards won't block in wait_for_completion which means return from smc/hvc is actually completion too which is clearly wrong or am I missing something ? Jim, please confirm either way. If you agree I can add the below snippet, no need to repost. Regards, Sudeep -- diff --git i/drivers/firmware/arm_scmi/smc.c w/drivers/firmware/arm_scmi/smc.c index fd41d436e34b..86eac0831d3c 100644 --- i/drivers/firmware/arm_scmi/smc.c +++ w/drivers/firmware/arm_scmi/smc.c @@ -144,6 +145,8 @@ static int smc_send_message(struct scmi_chan_info *cinfo, shmem_tx_prepare(scmi_info->shmem, xfer); + if (scmi_info->irq) + reinit_completion(&scmi_info->tx_complete); arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res); if (scmi_info->irq) wait_for_completion(&scmi_info->tx_complete);