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=-7.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=no 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 DF94FC433E1 for ; Sat, 15 Aug 2020 22:10:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A88F020639 for ; Sat, 15 Aug 2020 22:10:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597529432; bh=LWZ3gG05lyWwHbQNUP3ksCUHLVF4wFzI8rRKV3uiNak=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=a8N1gzhnhyw8r2coYL0wZrayTAKv7rVNpT3hyIs5TnehMNBj6R2HCQa3dSjCjeZkU CHeAS87MwNoBsFKvsnCiBfUS8ES247XKfphVErKrYKL7MHMRt7dkZT1nK/erXT8FQA Fz5kKLYyRCARMUMERdv0IzoPYjpVN/Oo6rC3sVGY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729512AbgHOWKb (ORCPT ); Sat, 15 Aug 2020 18:10:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:41776 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728715AbgHOWK1 (ORCPT ); Sat, 15 Aug 2020 18:10:27 -0400 Received: from mail-ej1-f53.google.com (mail-ej1-f53.google.com [209.85.218.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2C87322E00; Sat, 15 Aug 2020 03:03:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597460618; bh=LWZ3gG05lyWwHbQNUP3ksCUHLVF4wFzI8rRKV3uiNak=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=aPLmc5XIVhNgOz/dUkmBwJHhTub2jfiFdCUnXPgEVZvsfdM60xwqSPiHXUjZo/gZg W13nLli/i5dcL9+RLLKwoyKEj/1rS4pFIGP+81I7TUivDsE3PPl0LwR+oPRQbUf2eR Zq7320V1UEnYBmGlW09/3R0ltEf9DMa1/eUQy5SE= Received: by mail-ej1-f53.google.com with SMTP id o18so11890552eje.7; Fri, 14 Aug 2020 20:03:38 -0700 (PDT) X-Gm-Message-State: AOAM532l65Y/ZcRSYu08JznzZJX4t0VbxK+0NyP7fgsbMXobqvSx6uR6 V4hyvhlOtaj5s/12iSBYqiYEfVXTgvT5G9IeYQ== X-Google-Smtp-Source: ABdhPJyt/63tP7h7Rcip1YksjvsGO7WzFuUVEIVYhoFntsd6TkK7JtmalTJjkuyszotatOlhPqyFfaDNHeccHlw5oaU= X-Received: by 2002:a17:906:7492:: with SMTP id e18mr5232063ejl.375.1597460616714; Fri, 14 Aug 2020 20:03:36 -0700 (PDT) MIME-Version: 1.0 References: <1597289564-17030-1-git-send-email-neal.liu@mediatek.com> <1597289564-17030-3-git-send-email-neal.liu@mediatek.com> In-Reply-To: <1597289564-17030-3-git-send-email-neal.liu@mediatek.com> From: Chun-Kuang Hu Date: Sat, 15 Aug 2020 11:03:24 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 2/2] soc: mediatek: add mt6779 devapc driver To: Neal Liu Cc: Rob Herring , Matthias Brugger , devicetree@vger.kernel.org, wsd_upstream , lkml , "moderated list:ARM/Mediatek SoC support" , Linux ARM Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Neal: Neal Liu =E6=96=BC 2020=E5=B9=B48=E6=9C=8813=E6=97= =A5 =E9=80=B1=E5=9B=9B =E4=B8=8A=E5=8D=8811:33=E5=AF=AB=E9=81=93=EF=BC=9A > > MediaTek bus fabric provides TrustZone security support and data > protection to prevent slaves from being accessed by unexpected > masters. > The security violation is logged and sent to the processor for > further analysis or countermeasures. > > Any occurrence of security violation would raise an interrupt, and > it will be handled by mtk-devapc driver. The violation > information is printed in order to find the murderer. > > Signed-off-by: Neal Liu > --- [snip] > +/* > + * devapc_violation_irq - the devapc Interrupt Service Routine (ISR) wil= l dump > + * violation information including which master v= iolates > + * access slave. > + */ > +static irqreturn_t devapc_violation_irq(int irq_number, > + struct mtk_devapc_context *ctx) > +{ > + /* > + * Mask slave's irq before clearing vio status. > + * Must do it to avoid nested interrupt and prevent > + * unexpected behavior. > + */ > + mask_module_irq(ctx, true); I still don't understand why nested interrupt happen. If two CPU process different devapc interrupt at the same time, mask interrupt could not prevent these two CPU to sync vio dbg at the same time. As I know, in ARM CPU, only CPU0 process irq handler, and all devapc interrupt has the same priority, so why nested interrupt happen? Could you explain more detail about how nested interrupt happen? > + > + while (devapc_sync_vio_dbg(ctx)) > + devapc_extract_vio_dbg(ctx); > + > + /* > + * Ensure that violation info are written > + * before further operations > + */ > + smp_mb(); > + > + clear_vio_status(ctx); > + mask_module_irq(ctx, false); > + > + return IRQ_HANDLED; > +} > + [snip] > + > +static int mtk_devapc_remove(struct platform_device *pdev) > +{ > + struct mtk_devapc_context *ctx =3D platform_get_drvdata(pdev); > + > + stop_devapc(ctx); > + > + if (ctx->infra_clk) This always true. Regards, Chun-Kuang. > + clk_disable_unprepare(ctx->infra_clk); > + > + return 0; > +} > + > +static struct platform_driver mtk_devapc_driver =3D { > + .probe =3D mtk_devapc_probe, > + .remove =3D mtk_devapc_remove, > + .driver =3D { > + .name =3D KBUILD_MODNAME, > + .of_match_table =3D mtk_devapc_dt_match, > + }, > +}; > + > +module_platform_driver(mtk_devapc_driver); > + > +MODULE_DESCRIPTION("Mediatek Device APC Driver"); > +MODULE_AUTHOR("Neal Liu "); > +MODULE_LICENSE("GPL"); > -- > 1.7.9.5 > _______________________________________________ > Linux-mediatek mailing list > Linux-mediatek@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-mediatek