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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7EB3C4167B for ; Fri, 1 Dec 2023 15:33:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379467AbjLAPdn (ORCPT ); Fri, 1 Dec 2023 10:33:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379441AbjLAPdm (ORCPT ); Fri, 1 Dec 2023 10:33:42 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5B2D51A6 for ; Fri, 1 Dec 2023 07:33:48 -0800 (PST) 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 82A221007; Fri, 1 Dec 2023 07:34:34 -0800 (PST) Received: from bogus (unknown [10.57.42.162]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 544683F73F; Fri, 1 Dec 2023 07:33:46 -0800 (PST) Date: Fri, 1 Dec 2023 15:31:45 +0000 From: Sudeep Holla To: Cristian Marussi Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sudeep Holla , vincent.guittot@linaro.org, souvik.chakravarty@arm.com, nicola.mazzucato@arm.com Subject: Re: [PATCH] firmware: arm_scmi: Add protocol versioning checks Message-ID: <20231201153145.emneavw53en4hsju@bogus> References: <20231201135858.2367651-1-cristian.marussi@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231201135858.2367651-1-cristian.marussi@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 01, 2023 at 01:58:58PM +0000, Cristian Marussi wrote: > Platform and agent supported protocols versions do not necessarily match. > > When talking to an older platform SCMI server, supporting only older > protocol versions, the kernel SCMI agent will downgrade the version of > the used protocol to match the platform one and avoid compatibility issues. > > In the case, instead, in which the agent happens to communicate with a > newer platform server which can support newer protocol versions unknown to > the agent, and potentially backward incompatible, the agent currently > carries on, silently, in a best-effort approach. > > Note that the SCMI server, by the specification, has no means to explicitly > detect the protocol versions used by the agents, neither it is required to > support multiple, older, protocol versions. > > Add an explicit protocol version check to let the agent detect when this > version mismatch happens and warn the user about this condition. > > Signed-off-by: Cristian Marussi > --- > Any suggestion for a more meaningful warn message is very much welcome. Looks good to me. I will apply soon with couple of changes as mentioned below. Let me know if you agree/disagree. > Based on sudeep/for-next/scmi/updates > --- > drivers/firmware/arm_scmi/base.c | 6 +++++- > drivers/firmware/arm_scmi/clock.c | 6 +++++- > drivers/firmware/arm_scmi/driver.c | 11 ++++++++++- > drivers/firmware/arm_scmi/perf.c | 6 +++++- > drivers/firmware/arm_scmi/power.c | 6 +++++- > drivers/firmware/arm_scmi/powercap.c | 6 +++++- > drivers/firmware/arm_scmi/protocols.h | 8 +++++++- > drivers/firmware/arm_scmi/reset.c | 6 +++++- > drivers/firmware/arm_scmi/sensors.c | 6 +++++- > drivers/firmware/arm_scmi/system.c | 6 +++++- > drivers/firmware/arm_scmi/voltage.c | 6 +++++- > 11 files changed, 62 insertions(+), 11 deletions(-) > > diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c > index a52f084a6a87..3f5c89ae5af2 100644 > --- a/drivers/firmware/arm_scmi/base.c > +++ b/drivers/firmware/arm_scmi/base.c > @@ -13,6 +13,9 @@ > #include "common.h" > #include "notify.h" > > +/* Must be updated only after ALL new features for that version are merged */ s/new/mandatory/ > +#define SCMI_PROTOCOL_SUPPORTED_VERSION 0x20000 > + > #define SCMI_BASE_NUM_SOURCES 1 > #define SCMI_BASE_MAX_CMD_ERR_COUNT 1024 > > index 3eb19ed6f148..46320f627066 100644 > --- a/drivers/firmware/arm_scmi/driver.c > +++ b/drivers/firmware/arm_scmi/driver.c > @@ -1849,6 +1853,11 @@ scmi_alloc_init_protocol_instance(struct scmi_info *info, > devres_close_group(handle->dev, pi->gid); > dev_dbg(handle->dev, "Initialized protocol: 0x%X\n", pi->proto->id); > > + if (pi->version > proto->supported_version) > + dev_warn(handle->dev, > + "Detected UNSUPPORTED version 0x%X for protocol 0x%X. Backward compatibility is NOT assured.\n", s/UNSUPPORTED version/UNSUPPORTED newer version/ or higher instead of newer -- Regards, Sudeep