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 7B5C1C433E7 for ; Mon, 12 Oct 2020 08:57:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C17320773 for ; Mon, 12 Oct 2020 08:57:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728884AbgJLI55 (ORCPT ); Mon, 12 Oct 2020 04:57:57 -0400 Received: from foss.arm.com ([217.140.110.172]:59472 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726104AbgJLI55 (ORCPT ); Mon, 12 Oct 2020 04:57:57 -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 48EA031B; Mon, 12 Oct 2020 01:57:56 -0700 (PDT) Received: from bogus (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 833103F66B; Mon, 12 Oct 2020 01:57:54 -0700 (PDT) Date: Mon, 12 Oct 2020 09:57:38 +0100 From: Sudeep Holla To: Etienne Carriere Cc: linux-kernel@vger.kernel.org, "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" , Cristian Marussi , Vincent Guittot , Souvik Chakravarty , Sudeep Holla , Peng Fan Subject: Re: [PATCH 4/5] firmware: arm_scmi: smc transport supports multi-message pool Message-ID: <20201012085546.GA16519@bogus> References: <20201008143722.21888-1-etienne.carriere@linaro.org> <20201008143722.21888-4-etienne.carriere@linaro.org> <20201008211116.l6gbym2ypb6lzlo7@bogus> <20201009151752.fxqakqrritrgzo4r@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201009151752.fxqakqrritrgzo4r@bogus> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 09, 2020 at 04:17:52PM +0100, Sudeep Holla wrote: > On Fri, Oct 09, 2020 at 02:43:31PM +0200, Etienne Carriere wrote: > > On Thu, 8 Oct 2020 at 23:11, Sudeep Holla wrote: > > > > > > On Thu, Oct 08, 2020 at 04:37:21PM +0200, Etienne Carriere wrote: > > > > There is no reason for the smc transport to restrict itself to a 1 > > > > message pool. More can be allocated, messages are copied from/to the > > > > shared memory only on SMC exit/entry hence SCMI driver can play with > > > > several messages. > > > > > > > > Use value of 20 to mimic mailbox transport implementation. > > > > > > What is the need to mimic ? > > > > I had to pick a value. I can't say whether 2, 5 or 20 is better. > > I looks how the mailbox transport did and used the same value > > as it seemed reasonable regarding its memory cost. > > > > > > > > > Any high value could fit. This should be something configurable. > > > > > > Why not 10 or 100 ? I see any value other than 1 is useless as we lock > > > the channel in send_message and we don't maintain a queue like mailbox. > > > > I'll check again. > > Playing with SCMI voltage domain [1], it happens that I needed several > > preallocated message buffers unless what regulators fail to be probed. > > > I may be missing something but I can't see how, we simply block in > send_message while mailbox has a queue of 20 which is why it has 20 there. > > The issue you are seeing could be different. Let me know if I am missing > something. > OK, I gave this some thought and realise that in-order to allow multiple requests simultaneously, we do need this value > 1. I will take this and make some tweaks to the commit log to indicate the same. -- Regards, Sudeep