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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=ham 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 36A96C07E99 for ; Mon, 5 Jul 2021 17:10:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0DFBD61935 for ; Mon, 5 Jul 2021 17:10:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229753AbhGERNT (ORCPT ); Mon, 5 Jul 2021 13:13:19 -0400 Received: from foss.arm.com ([217.140.110.172]:51116 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229689AbhGERNS (ORCPT ); Mon, 5 Jul 2021 13:13:18 -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 EFAC46D; Mon, 5 Jul 2021 10:10:40 -0700 (PDT) Received: from e120937-lin.home (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 05B693F694; Mon, 5 Jul 2021 10:10:38 -0700 (PDT) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: sudeep.holla@arm.com, james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com, f.fainelli@gmail.com, etienne.carriere@linaro.org, vincent.guittot@linaro.org, souvik.chakravarty@arm.com, cristian.marussi@arm.com Subject: [RFC PATCH v2 0/8] Introduce atomic support for SCMI transports Date: Mon, 5 Jul 2021 18:10:14 +0100 Message-Id: <20210705171022.25861-1-cristian.marussi@arm.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi all, This RFC series mainly aims to introduce atomic support for transports that can support it. At first in [1/8], as a closely related addition, it is introduced a common way for a transport to signal to the SCMI core that it does not offer completion interrupts, so that the usual polling behaviour based on .poll_done() will be required: this can be done enabling statically a global polling behaviour for the whole transport with flag scmi_desc.force_polling OR dynamically enabling at runtime such polling behaviour on a per-channel basis with scmi_chan_info.needs_polling, typically during .chan_setup(). The usual per-command polling selection behaviour based on hdr.poll_completion is preserved as before. Then in [2/8], a transport that supports atomic operations on its tx path can now declare itself as .atomic_capable and as a consequence the SCMI core will refrain itself from sleeping on the correspondent rx-path. In [5/8] a simple method is introduced so that an SCMI driver can easily query the core to check if the currently used transport is configured to behave in an atomic manner: in this way, interested SCMI driver users, like Clock framework [6/8], can optionally support atomic operations when operating on an atomically configured transport. Finally there are 2 *tentative" patch for SMC transport: at first [7/8] ports SMC to use the common core completions when completion interrupt is available or otherwise revert to use common core polling mechanism above introduced; then in [8/8] SMC is converted to be .atomic_capable by substituting the mutexes with busy-waiting to keep the channel 'locked'. SMC changes have NOT been tested so far (I cannot), AND they are just a proposal at this stage to try to better abstract and unify behaviour with the SCMI core; both patches are completely intended as RFCs, though, not only regarding their implementation but even their mere existence is RFC: I mean maybe we just don't want to do such kind of unification/abstraction, and I can just drop those SMC patches if unwanted; any feedback welcome. Atomic support has been minimally tested against the upcoming virtio transport V5 series, while polling has been tested with mailbox transports. The series is based on SCMI VirtIO Transport support V5 [1] (since it will be the main prospective user of atomic mode) and, as such, it is also publicly available from ARM GitLab [2]. (Note that in order to use/test atomic mode on virtio you'll have to enable it setting .atomic_capable = true in virtio.c::scmi_virtio_desc) Given the RFC status of the series in general I still not have CCed any maintainer out of SCMI subsystem. Any feedback welcome. Thanks, Cristian --- [1]:https://lore.kernel.org/linux-arm-kernel/20210705144914.35094-1-cristian.marussi@arm.com/ [2]:https://gitlab.arm.com/linux-arm/linux-cm/-/commits/scmi_atomic_transport_V2_on_virtio/ Cristian Marussi (8): firmware: arm_scmi: Add configurable polling mode for transports firmware: arm_scmi: Add support for atomic transports include: trace: Add new scmi_xfer_response_wait event firmware: arm_scmi: Use new trace event scmi_xfer_response_wait firmware: arm_scmi: Add is_transport_atomic() handle method clk: scmi: Support atomic enable/disable API firmware: arm_scmi: Make smc transport use common completions firmware: arm_scmi: Make smc transport atomic drivers/clk/clk-scmi.c | 44 ++++-- drivers/firmware/arm_scmi/common.h | 13 ++ drivers/firmware/arm_scmi/driver.c | 206 +++++++++++++++++++++++------ drivers/firmware/arm_scmi/smc.c | 60 +++++---- include/linux/scmi_protocol.h | 8 ++ include/trace/events/scmi.h | 28 ++++ 6 files changed, 288 insertions(+), 71 deletions(-) -- 2.17.1