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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 D04D2C55179 for ; Thu, 5 Nov 2020 18:27:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7ED7E20936 for ; Thu, 5 Nov 2020 18:27:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731648AbgKES1Q (ORCPT ); Thu, 5 Nov 2020 13:27:16 -0500 Received: from foss.arm.com ([217.140.110.172]:39630 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726214AbgKES1Q (ORCPT ); Thu, 5 Nov 2020 13:27:16 -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 02CC01474; Thu, 5 Nov 2020 10:27:15 -0800 (PST) Received: from bogus (unknown [10.57.22.191]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BEDDE3F719; Thu, 5 Nov 2020 10:27:13 -0800 (PST) Date: Thu, 5 Nov 2020 18:27:07 +0000 From: Sudeep Holla To: Jim Quinlan Cc: Rob Herring , "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" , Florian Fainelli , Sudeep Holla , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE" , open list Subject: Re: [PATCH v4 1/2] dt-bindings: Add bindings for BrcmSTB SCMI mailbox driver Message-ID: <20201105182707.l4xx3wu2ch22qysi@bogus> References: <20201029195913.5927-1-james.quinlan@broadcom.com> <20201029195913.5927-2-james.quinlan@broadcom.com> <20201104215050.GA4180546@bogus> 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 Thu, Nov 05, 2020 at 10:28:25AM -0500, Jim Quinlan wrote: > On Thu, Nov 5, 2020 at 10:13 AM Rob Herring wrote: > > > > On Wed, Nov 4, 2020 at 4:04 PM Jim Quinlan wrote: > > > > > > On Wed, Nov 4, 2020 at 4:50 PM Rob Herring wrote: > > > > > > > > On Thu, Oct 29, 2020 at 03:59:06PM -0400, Jim Quinlan wrote: > > > > > Bindings are added. Only one interrupt is needed because > > > > > we do not yet employ the SCMI p2a channel. > > > > > > > > I still don't understand what this is. To repeat from v1: I thought SCMI > > > > was a mailbox consumer, not provider? > > > > > > Hi Rob, > > > > > > I'm not sure where I am implying that SCMI is a mailbox provider? > > > Should I not mention "SCMI" in the subject line? > > > > > > This is just a mailbox driver, "consumed" by SCMI. Our SCMI DT node > > > looks like this: > > > > > > brcm_scmi_mailbox: brcm_scmi_mailbox@0 { > > > #mbox-cells = <1>; > > > compatible = "brcm,brcmstb-mbox"; > > > }; > > > > > > brcm_scmi@0 { > > > compatible = "arm,scmi"; > > > mboxes = <&brcm_scmi_mailbox 0>;; > > > mbox-names = "tx"; > > > shmem = <&NWMBOX>; > > > /* ... */ > > > }; > > > > Okay, that makes more sense. Though it seems like this is just adding > > a pointless level of indirection to turn an interrupt into a mailbox. > > There's nothing more to 'the mailbox' is there? > > Correct. Although you can see that it uses both interrupts and SMC > calls to get the job done. > I was against having 2 separate solutions and would have raised my concern again. As I mentioned earlier, either extend what we have or move the existing SMC solution into this mailbox driver. Having 2 different solution for this just because you have extra interrupt to deal with is definite NACK from me as I had previously mentioned. > > So why not either > > allow SCMI to have an interrupt directly > Not sure here -- perhaps the SCMI folks have an answer? > I did ask why can't you extend the existing SCMI/SMC binding to add this as optional feature ? > > or have a generic irq mailbox driver? Fine with this too. > The SCMI implementation doesn't offer a generic irq mailbox driver > AFAICT. The SCMI folks recently provided an "smc transport" driver > in "drivers/firmware/arm_scmi/smc.c" -- it is close to what we need > but is missing interrupts. IIRC, you were using SGIs and it can't be represented and use today as is ? Am I missing something or anything has changed ? -- Regards, Sudeep