[{"id":3677311,"web_url":"http://patchwork.ozlabs.org/comment/3677311/","msgid":"<2026041418-volley-composer-6363@gregkh>","list_archive_url":null,"date":"2026-04-14T16:49:35","subject":"Re: [PATCH 1/3] drivers: base: Add generic context device bus","submitter":{"id":11800,"url":"http://patchwork.ozlabs.org/api/people/11800/","name":"Greg Kroah-Hartman","email":"gregkh@linuxfoundation.org"},"content":"On Tue, Apr 14, 2026 at 10:01:15PM +0530, Ekansh Gupta via B4 Relay wrote:\n> From: Ekansh Gupta \n> \n> Introduce a new generic bus type for synthetic context bank devices\n> that require IOMMU context isolation. This bus provides a shared\n> infrastructure for accelerator and GPU drivers that create virtual\n> devices representing IOMMU context banks.\n> \n> Currently, drivers like host1x implement their own bus types for\n> context devices. This generic implementation allows multiple drivers\n> to share the same bus infrastructure, simplifying the IOMMU subsystem\n> integration and reducing code duplication.\n> \n> Signed-off-by: Ekansh Gupta \n> ---\n> drivers/base/Kconfig | 3 +++\n> drivers/base/Makefile | 1 +\n> drivers/base/context_bus.c | 24 ++++++++++++++++++++++++\n> include/linux/context_bus.h | 15 +++++++++++++++\n> 4 files changed, 43 insertions(+)\n> \n> diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig\n> index f7d385cbd3ba..479bc4bb442b 100644\n> --- a/drivers/base/Kconfig\n> +++ b/drivers/base/Kconfig\n> @@ -4,6 +4,9 @@ menu \"Generic Driver Options\"\n> config AUXILIARY_BUS\n> \tbool\n> \n> +config CONTEXT_DEVICE_BUS\n> +\tbool\n\nSo this is a context-free bus? I.e. no documentation?\n\n:)\n\nThis feels really odd, this \"bus\" isn't doing anything at all. So why\ndo you need it and can't use auxbus or faux? \n\nYou say something about an iommu, but yet this has no information about\nan iommu at all, so why are they somehow special?\n\nYou need to provide a lot more information here, sorry.\n\ngreg k-h","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-tegra@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org\n header.a=rsa-sha256 header.s=korg header.b=qLFpEGvN;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; helo=tor.lore.kernel.org;\n envelope-from=linux-tegra+bounces-13764-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (1024-bit key) header.d=linuxfoundation.org\n header.i=@linuxfoundation.org header.b=\"qLFpEGvN\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=10.30.226.201"],"Received":["from tor.lore.kernel.org (tor.lore.kernel.org\n [IPv6:2600:3c04:e001:36c::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fw9Hv4SD1z1y2d\n\tfor ; Wed, 15 Apr 2026 02:50:19 +1000 (AEST)","from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby tor.lore.kernel.org (Postfix) with ESMTP id 9344B3053BF0\n\tfor ; Tue, 14 Apr 2026 16:50:07 +0000 (UTC)","from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id 293163EC2CB;\n\tTue, 14 Apr 2026 16:50:06 +0000 (UTC)","from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org\n [10.30.226.201])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby smtp.subspace.kernel.org (Postfix) with ESMTPS id CFA462253EC;\n\tTue, 14 Apr 2026 16:50:05 +0000 (UTC)","by smtp.kernel.org (Postfix) with ESMTPSA id E5F30C19425;\n\tTue, 14 Apr 2026 16:50:04 +0000 (UTC)"],"ARC-Seal":"i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1776185405; cv=none;\n b=SFWSUHYj/F/21jmZvg/gM7em7WlvfeVsvL2k11kyVywHmN8FBWrLZVrEhGm6e1/JUVfBrPYTvN8EUvPFSLCxjsZNDHGgy/MhxgMgkt+oQ7/lHJQ/i1sa0/EYIY9eT66jbJtDXY4Lcg+yT7fAylASXd/Somql2Wka746gn0wZXhA=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1776185405; c=relaxed/simple;\n\tbh=Dge0DCS/QYtIgyrk1+RNGXNQhBsk1R+oQTAvvrTBHr0=;\n\th=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version:\n\t Content-Type:Content-Disposition:In-Reply-To;\n b=QgBrcqtMHNUbz6oO1y+FuO2pqpQB33U3rMeoyVtZEsKVnhYi9xFTMRdm6VG1ap59S+Xt8zYYWsOHGXWehPQTIL4ES1xGmHytQkanf4YMgnnNE7pIWrbtyMc9v9JKFVPDcvc4PkYpyQ5KOY56vDRTIW7hu/0oGuk2bLFRdObpN38=","ARC-Authentication-Results":"i=1; smtp.subspace.kernel.org;\n dkim=pass (1024-bit key) header.d=linuxfoundation.org\n header.i=@linuxfoundation.org header.b=qLFpEGvN;\n arc=none smtp.client-ip=10.30.226.201","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org;\n\ts=korg; t=1776185405;\n\tbh=Dge0DCS/QYtIgyrk1+RNGXNQhBsk1R+oQTAvvrTBHr0=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=qLFpEGvNOn2J0c3amth0T/BSS+qAPInX3J/3HfeiAHDkONa2ZuJWdBe2JmaB48Vsy\n\t 8yH51OyTrvDIOmka54WHeVakebbJVkeAn5lSkClMKw5rdVnpJMF7H8+02i/sxwXgCD\n\t 4co+tT3gSWcz22dRr8rE1irOoT5huoJmemctg5mA=","Date":"Tue, 14 Apr 2026 18:49:35 +0200","From":"Greg Kroah-Hartman ","To":"ekansh.gupta@oss.qualcomm.com","Cc":"\"Rafael J. Wysocki\" ,\n\tDanilo Krummrich ,\n\tThierry Reding ,\n\tMikko Perttunen ,\n\tDavid Airlie , Simona Vetter ,\n\tJoerg Roedel , Will Deacon ,\n\tRobin Murphy , Arnd Bergmann ,\n\tSrinivas Kandagatla ,\n\tDmitry Baryshkov ,\n\tBharath Kumar ,\n\tChenna Kesava Raju ,\n\tlinux-kernel@vger.kernel.org, driver-core@lists.linux.dev,\n\tdri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org,\n\tiommu@lists.linux.dev, linux-arm-msm@vger.kernel.org","Subject":"Re: [PATCH 1/3] drivers: base: Add generic context device bus","Message-ID":"<2026041418-volley-composer-6363@gregkh>","References":"<20260414-computebus-v1-0-4d904d40926a@oss.qualcomm.com>\n <20260414-computebus-v1-1-4d904d40926a@oss.qualcomm.com>","Precedence":"bulk","X-Mailing-List":"linux-tegra@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20260414-computebus-v1-1-4d904d40926a@oss.qualcomm.com>"}}]