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=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 B7BB6C04AB5 for ; Thu, 6 Jun 2019 15:41:00 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 923A0206BB for ; Thu, 6 Jun 2019 15:41:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="kET2K43+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 923A0206BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=de8ro4AxnpsN/YtJs21AxYKbIoTEvc0mrk+zuXY5yI0=; b=kET2K43+0MHMJH OuZmhWNYTjiqTBWMJ/uFK0OlVgmvMnRGLfu5kKZ+TCcDKRVK9LB71O2X2Py0Hz/vd83c1FS9KV8xC wwc/hP/iFbIwxUUem0B+rj8Ljl+2hUW+YVXaeaVOtJ/7rzp22G0iFUxwznHDTalXkwSNcZWkh+5H1 GiEwYkQGMrpkBU/kHwo/MR8jTJf3aVenfdo5o/qDmCu9FEqdaN+BBNmccfyafvb4cn1I8XtZINVcX zNXAOQoIjhqwmsIBysqPvsNCsyyRy19CxIpGXe5YVHZ+kxu5OkF4g2ud09OyT1IiQkZBNpUjzDe5C Y6IpX1KLmzyNt0h+jF7w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hYuVf-0000fa-L8; Thu, 06 Jun 2019 15:40:59 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hYuVb-0000et-OX for linux-arm-kernel@lists.infradead.org; Thu, 06 Jun 2019 15:40:57 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0760DA78; Thu, 6 Jun 2019 08:40:54 -0700 (PDT) Received: from e107155-lin (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5D8473F690; Thu, 6 Jun 2019 08:40:52 -0700 (PDT) Date: Thu, 6 Jun 2019 16:40:45 +0100 From: Sudeep Holla To: Jassi Brar Subject: Re: [PATCH 0/6] mailbox: arm_mhu: add support to use in doorbell mode Message-ID: <20190606154045.GA2429@e107155-lin> References: <20190531143320.8895-1-sudeep.holla@arm.com> <20190531165326.GA18115@e107155-lin> <20190603193946.GC2456@sirena.org.uk> <20190604093827.GA31069@e107533-lin.cambridge.arm.com> <20190605194636.GW2456@sirena.org.uk> <20190606125140.GB26273@e107155-lin> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190606_084055_806463_D33EC451 X-CRM114-Status: GOOD ( 21.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Arnd Bergmann , Mark Brown , Linux Kernel Mailing List , Bjorn Andersson , Rob Herring , Cristian Marussi , Sudeep Holla , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jun 06, 2019 at 10:20:40AM -0500, Jassi Brar wrote: > On Thu, Jun 6, 2019 at 7:51 AM Sudeep Holla wrote: > > > > > > BTW, this is not going to be the end of SCMI troubles (I believe > > > that's what his client is). SCMI will eventually have to be broken up > > > in layers (protocol and transport) for many legit platforms to use it. > > > That is mbox_send_message() will have to be replaced by, say, > > > platform_mbox_send() in drivers/firmware/arm_scmi/driver.c OR the > > > platforms have to have shmem and each mailbox controller driver (that > > > could ever be used under scmi) will have to implement "doorbell > > > emulation" mode. That is the reason I am not letting the way paved for > > > such emulations. > > > > > > > While I don't dislike or disagree with separate transport in SCMI which > > I have invested time and realised that I will duplicate mailbox framework > > at the end. > > > Can you please share the code? Or is it no more available? > > > So I am against it only because of duplication and extra > > layer of indirection which has performance impact(we have this seen in > > sched governor for DVFS). > > > I don't see why the overhead should increase noticeably. > Simple, if 2 protocols share the same channel, then the requests are serialised. E.g. if bits 0 and 1 are allocated for protocol#1 and bits 2 and 3 for protocol#2 and protocol#1 has higher latency requirements like sched-governor DVFS and there are 3-4 pending requests on protocol#2, then the incoming request for protocol#1 is blocked. > > So idea wise, it's good and I don't disagree > > with practically seen performance impact. Hence I thought it's sane to > > do something I am proposing. > > > Please suggest how is SCMI supposed to work on ~15 controllers > upstream (except tegra-hsp) ? > Do you mean we have to implement platform layer to make it work ? That's not necessary IMO. > > It also avoids coming up with virtual DT > > nodes for this layer of abstract which I am completely against. > > > I don't see why virtual DT nodes would be needed for platform layer. So how will 2 or more different users of the same mailbox identify the bits allocated for them ? -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel