From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-103.mailbox.org (mout-p-103.mailbox.org [80.241.56.161]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 88E021F956; Thu, 30 Oct 2025 00:52:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.161 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761785577; cv=none; b=UqPQ70mayZd3RrklwxrLvMW46ouduUBu5nbzC9mffrsQSrrX/q4zKeCxh75NXwFHdsKtujnwRzmuKrKu/O1l931rCq1UAFDDUpf+0/cOC2CbBxge4wBmtn6j1Tc6L6qDODvGp2oC/bk/fRBiqgGWcFVdYEPk5rRy13B9IVkPlQI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761785577; c=relaxed/simple; bh=LIztsZWCnsp19S5Dn+/450IkiPd7MZ+AWYnflbZ3Ht0=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=up66MaY9YE02xUsBdIowaFQxtrHUHuqV91i/CyybLgYX1kFwac2n8aozh4Nd/gGWbnVQ9hYejBSijs3QZkfJIIA4zhRwvOu5Y2VjPtZ5bm5a06Hk6sj56V8NMtkbY9woIsSw8fWaBsLoqxUE8gXnVTcsvIF3qVzVtNtbGimvzI0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org; spf=pass smtp.mailfrom=mailbox.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=kEI1bBYy; arc=none smtp.client-ip=80.241.56.161 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mailbox.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="kEI1bBYy" Received: from smtp202.mailbox.org (smtp202.mailbox.org [IPv6:2001:67c:2050:b231:465::202]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-103.mailbox.org (Postfix) with ESMTPS id 4cxlvd0Hprz9scQ; Thu, 30 Oct 2025 01:52:45 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1761785565; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IniilaBss4ARvgvSKGFl6OJKKn5eXDeB1rP41HTysu0=; b=kEI1bBYyyLEhaTuVznkOU9OUJQPU6XXU4pjIJhf1QXSwTb0uh2uh2IwGh28dDJeCZjZzTK DtWIbPfSDMmnGNqf1+YWJqqZeWEcZiw6GJak0wTW7SOilU4bBoAODKKLw4OuH2siLnewHc vVKjAh5Yx0CmtFQjNUloAi/e1ZGGDf8ndvO4weaCG2vTllk3hP7GMeX8wHj5znHHbqpz8C ZvJ0fw3lOsDOjphHR3xXI3ejXu1sPH/4j3yAZxtBW6XALi4JYUa8KISnK1VxFIss5DJq9f ywYnWWdRIP28CQnxUsDhpthZSRUxygTaR+Oc06o1xnwkitIQX/kBy0va5NcnUA== Message-ID: <5ae0a793-d3e7-45d1-bf5c-3c46593d1824@mailbox.org> Date: Thu, 30 Oct 2025 01:52:42 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 1/2] dt-bindings: firmware: arm,scmi: Document arm,poll-transport property From: Marek Vasut To: Cristian Marussi Cc: arm-scmi@vger.kernel.org, Conor Dooley , Florian Fainelli , Krzysztof Kozlowski , Rob Herring , Sudeep Holla , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-renesas-soc@vger.kernel.org References: <20251023123644.8730-1-marek.vasut+renesas@mailbox.org> <70554674-7020-4582-a4e7-dbee34907096@mailbox.org> Content-Language: en-US In-Reply-To: <70554674-7020-4582-a4e7-dbee34907096@mailbox.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-MBO-RS-META: meqz3wrctz4xpsm9cpmk745gwhfgm5x4 X-MBO-RS-ID: 1b87ccad0ed6c2ee2ee On 10/23/25 4:00 PM, Marek Vasut wrote: Hello again, >> 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... > > Correct, at least until the SCP on this hardware is updated. > >> ...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... > > These systems are early in development and it is likely that the SCP > will be updated to generate interrupts properly. Currently, this is not > the case, hence the carpet-polling, until this is resolved. While I was going through the SCMI spec, DEN0056F , page 209 , section "4.1 Shared memory based transport" , bullet • Completion interrupts, I found it explicitly states: " This transport supports polling or interrupt driven modes of communication. In interrupt mode, when the callee completes processing a message, it raises an interrupt to the caller. Hardware support for completion interrupts is optional. " -- Best regards, Marek Vasut