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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B6821CCD1BE for ; Thu, 23 Oct 2025 13:45:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=IgFDytu0jE6zFlGX1fDz906kNW4C+0Iw86IS8J1gB48=; b=TXxiNGS2AtX6TqpR3LoEUKxShQ MtAnvD8vONw/cxWksKadZbKGu+RMWQ4/CzG2SLjD/XzXVv48O59EB32yaj+RjnjHGHRYqMr7bTpo3 wH1D3k9j7N79DWdfq9+G62ykOi96NBGQ9DAU8xfC2k23o/1kIzNBpXn4PEAFIGu6UyIHnaBqaVnu6 kOk+FAOyqJuaPfZ+QfNCacE4DxmEe8FuK+BORqcwATcaR+y011k+7VoqFfsqJslxJrK56iX2zNxEw 5j3ajViWD9h9eXJr/7KI2PeFzdGRsdditkpYm84QIUhYwpX/V0OITOggzgGopTJFsNBHRpu88LeqE UKjOtJ0A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vBvdU-00000006SdF-25KP; Thu, 23 Oct 2025 13:45:48 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vBvdS-00000006ScP-05Cj for linux-arm-kernel@lists.infradead.org; Thu, 23 Oct 2025 13:45:47 +0000 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 97E8F1516; Thu, 23 Oct 2025 06:45:35 -0700 (PDT) Received: from pluto (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5DF743F63F; Thu, 23 Oct 2025 06:45:41 -0700 (PDT) Date: Thu, 23 Oct 2025 14:45:32 +0100 From: Cristian Marussi To: Marek Vasut Cc: arm-scmi@vger.kernel.org, Conor Dooley , Cristian Marussi , Florian Fainelli , Krzysztof Kozlowski , Rob Herring , Sudeep Holla , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH 1/2] dt-bindings: firmware: arm,scmi: Document arm,poll-transport property Message-ID: References: <20251023123644.8730-1-marek.vasut+renesas@mailbox.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251023123644.8730-1-marek.vasut+renesas@mailbox.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251023_064546_113760_DF6172D7 X-CRM114-Status: GOOD ( 14.00 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Oct 23, 2025 at 02:35:57PM +0200, Marek Vasut wrote: > Document new property arm,poll-transport, which sets all SCMI operation into > poll mode. This is meant to work around uncooperative SCP implementations, > which do not generate completion interrupts. This applies primarily on mbox > based implementations, but does also cover SMC and VirtIO ones. Hi, ..indeed I was thinking a while ago about exposing the existing force-polling switch but in my case it was purely a testing-scenario configuration, so a no-no for the DT, things are different if you have to describe an HW that has no completion IRQ also on the a2p channel... ...having said that, though, usually polling-mode is reserved to a few selected commands in a few chosen scenarios (as you may have seen), 'carpet-polling' non-for-testing for all the commands on A2P seems a lot inefficient and heavy...is it really a viable solution ? or these systems use such a low rate of SCMI messages that polling after each and every message is negligible ? ..just to understand the context... > > With this property set, such implementations which do not generate interrupts > can be interacted with, until they are fixed to generate interrupts properly. > > Note that, because the original base protocol exchange also requires some > sort of completion mechanism, it is not possible to query SCMI itself for > this property and it must be described in DT. While this does look a bit > like policy, the SCMI provider is part of the hardware, hence DT. > > Signed-off-by: Marek Vasut Thanks, Cristian