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=-8.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 20F2EC4338F for ; Mon, 26 Jul 2021 15:12:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D97D60F6C for ; Mon, 26 Jul 2021 15:12:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234837AbhGZObo (ORCPT ); Mon, 26 Jul 2021 10:31:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234423AbhGZObn (ORCPT ); Mon, 26 Jul 2021 10:31:43 -0400 Received: from mail-wr1-x436.google.com (mail-wr1-x436.google.com [IPv6:2a00:1450:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E99B2C061760 for ; Mon, 26 Jul 2021 08:12:11 -0700 (PDT) Received: by mail-wr1-x436.google.com with SMTP id b9so10663215wrx.12 for ; Mon, 26 Jul 2021 08:12:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brainfault-org.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=SEfxyBBsdqfeyLFZ2nbpK//+jCa1qE/9+zQ9LwwPbhQ=; b=H0hDtd3aCHUHBPDSloms35IgrhOF5ZtJrLGWMgoKlxm537RxzcsL1cQz8j97DDsHh9 ba257rXMv+VCd4/qPOgFYNJLD5tuoWUBjtD6sPNOQALBupambb2XeVKk8ONsoeSfbHT8 P0og8XIFWCRosGS0qbsF+IHvXILMCixoRzO/T9RqzuxSpCkiIkl0AQ+0BEWhxNPl9ooe zIyiJ1/swh7zXH7IE/GtocToTLAeZLfA2fmi2YZtTCR20VpKrQO9S4afpFoQHgp/OGXl zQ5uqrgZBrSXyRhgPl2HFBnkIiq1ONVTxN+RJ0GkiL6WB3NZz+wk2OG+msbmpicBJyPU xevQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SEfxyBBsdqfeyLFZ2nbpK//+jCa1qE/9+zQ9LwwPbhQ=; b=UMpLyFwzd3jzKWj6+1Zbb3N+qrw9/BVogeGm3FfJBrnYM2zRGb8wlxJmiajxPW18UP /cw6Hm3GYM5OiBozE+zjkUQHk31ZWunyfX6dt0jbaKyekrPRWQhDnY6RFJ+M748rvoHq Cqfmptv4aih6r/+XQqgjE8VxgH4kULWRE3WQ2GG9NLMXIms11Kd9hIQFb6x4qg/5VAO0 dnn7f9P+hqmKjBMfLFCHDQAmVN/sA5qfDvKs2uesQpisbhJ0L3iIirOjBDQ+h8I1+L42 EGAUCFZDVMRMhYiNoRB4/qMYUl32FJD4AFWlfQGdOOjxsGz3mYw5q86Cu1aQOxFXe4N2 mgFg== X-Gm-Message-State: AOAM533/z4Pm1w5VscHVwvt0+4rM+9BLXHAcdVIWru3SDh4xlpaivs+p ieGWvM1lwtgH5M4A2WgK6sgurjnQV77g4nCDh4Y2Ew== X-Google-Smtp-Source: ABdhPJy2FXmilr8kKAcECuQtFjx9dz7AcFI/haY3JRbMnk74CbCDdgkdvTEDD0AbKksuMyT9HXc0AHbJKw8GCdi7V4k= X-Received: by 2002:a5d:640f:: with SMTP id z15mr11915041wru.325.1627312330294; Mon, 26 Jul 2021 08:12:10 -0700 (PDT) MIME-Version: 1.0 References: <20210618123851.1344518-1-anup.patel@wdc.com> <87im0xdu2a.wl-maz@kernel.org> In-Reply-To: <87im0xdu2a.wl-maz@kernel.org> From: Anup Patel Date: Mon, 26 Jul 2021 18:31:01 +0530 Message-ID: Subject: Re: [RFC PATCH v2 00/11] Linux RISC-V ACLINT Support To: Marc Zyngier Cc: Palmer Dabbelt , Palmer Dabbelt , Paul Walmsley , Thomas Gleixner , Daniel Lezcano , Rob Herring , Atish Patra , Alistair Francis , linux-riscv , "linux-kernel@vger.kernel.org List" , DTML , Anup Patel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, On Mon, Jul 26, 2021 at 8:02 PM Marc Zyngier wrote: > > On Mon, 26 Jul 2021 13:45:20 +0100, > Anup Patel wrote: > > > > Hi Marc, > > > > I have taken the approach of IPI domains (like you suggested) in this series. > > > > What do you think ? > > I have commented on the irqchip driver. > > As for the RISC-V specific code, I'll let the architecture maintainers > look into it. I guess the elephant in the room is that this spec seems > to be evolving, and that there is no HW implementation (how this > driver maps on SF's CLINT is anybody's guess). The SiFive CLINT is a more convoluted device and provides M-level timer functionality and M-level IPI functionality in one MMIO device. The RISC-V ACLINT specification is more modular and backward compatible with the SiFive CLINT. In fact, a SiFive CLINT device can be viewed as a ACLINT MSWI device + ACLINT MTIMER device. This means existing RISC-V boards having SiFive CLINT will be automatically compliant to the RISC-V ACLINT specification. Here's the RISC-V ACLINT spec: https://github.com/riscv/riscv-aclint/blob/main/riscv-aclint.adoc The RISC-V ACLINT spec is quite stable and we are not seeing any further changes hence I sent out RFC PATCHes to get feedback. The RISC-V ACLINT spec will be frozen before 2021 end (i.e. before next RISC-V summit). The Linux NoMMU kernel (M-level) will use an ACLINT MSWI device for IPI support whereas the regular Linux MMU kernel (S-level) will use an ACLINT SSWI device for IPI support. The ACLINT SWI driver is a common IPI driver for both ACLINT MSWI (Linux NoMMU) and ACLINT SSWI (Linux MMU). In fact, the ACLINT SWI also works for IPI part (i.e. MSWI) of SiFive CLINT. Regards, Anup > > M. > > -- > Without deviation from the norm, progress is not possible.