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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 4491AC433DF for ; Fri, 15 May 2020 09:34:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 243E020727 for ; Fri, 15 May 2020 09:34:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728138AbgEOJea (ORCPT ); Fri, 15 May 2020 05:34:30 -0400 Received: from foss.arm.com ([217.140.110.172]:52002 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727803AbgEOJe3 (ORCPT ); Fri, 15 May 2020 05:34:29 -0400 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 BD32D2F; Fri, 15 May 2020 02:34:28 -0700 (PDT) Received: from bogus (unknown [10.37.12.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 75A863F71E; Fri, 15 May 2020 02:34:27 -0700 (PDT) Date: Fri, 15 May 2020 10:34:24 +0100 From: Sudeep Holla To: Etienne Carriere Cc: linux-kernel@vger.kernel.org, Sudeep Holla , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] firmware: arm_scmi: fix SMCCC_RET_NOT_SUPPORTED management Message-ID: <20200515093424.GC23671@bogus> References: <20200514082428.27864-1-etienne.carriere@linaro.org> <20200514142924.GC23401@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 14, 2020 at 05:06:22PM +0200, Etienne Carriere wrote: > On Thu, 14 May 2020 at 16:29, Sudeep Holla wrote: > > > > On Thu, May 14, 2020 at 10:24:28AM +0200, Etienne Carriere wrote: > > > Fix management of argument a0 output value of arm_smccc_1_1_invoke() that > > > should consider only SMCCC_RET_NOT_SUPPORTED as reporting an unsupported > > > function ID as correctly stated in the inline comment. > > > > > > > I agree on the comment part, but ... > > > > > Signed-off-by: Etienne Carriere > > > --- > > > drivers/firmware/arm_scmi/smc.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c > > > index 49bc4b0e8428..637ad439545f 100644 > > > --- a/drivers/firmware/arm_scmi/smc.c > > > +++ b/drivers/firmware/arm_scmi/smc.c > > > @@ -115,7 +115,7 @@ static int smc_send_message(struct scmi_chan_info *cinfo, > > > mutex_unlock(&scmi_info->shmem_lock); > > > > > > /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */ > > > - if (res.a0) > > > + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) > > > return -EOPNOTSUPP; > > > > Now this will return 0 for all values other than SMCCC_RET_NOT_SUPPORTED. > > Is that what we need ? Or do you see non-zero res.a0 for a success case ? > > If later, we need some fixing, otherwise it is safer to leave it as is > > IMO. > > Firmware following SMCCC v1.x for some OEM/SiP invocation may simply > not modify invocation register argument a0 on invocation with a > SCMI-SMC transport function ID. Yikes, I need to check specification again for this. I will also check with the firmware implementation team/ > Resulting in res.a0 == scmi_info->func_id here. Which is, by SMCCC > v1.x not an error. > But that may get fatal the result in some other cases, not here for sure. But I would rather flag that as error so that it is fixed. Anyways I will check on this again/ > From SMCCC v1.x only SMCCC_RET_NOT_SUPPORTED (-1 signed extended is a > reserved ) is a generic return error whatever function ID value. > Not really, there are couple more I think now. But yes I need to check on the generic return part. > Or consider part of the SCMI-SMC transport API that output arg a0 > shall be 0 on success, SMCCC_RET_NOT_SUPPORTED if function ID is not > supported and any non-zero value for non-generic **error** codes. > I prefer that. Anyways I will check and if anything changes I will ping back on this thread. -- Regards, Sudeep