From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CFA462253EC; Tue, 14 Apr 2026 16:50:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776185405; cv=none; 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; s=arc-20240116; t=1776185405; c=relaxed/simple; bh=Dge0DCS/QYtIgyrk1+RNGXNQhBsk1R+oQTAvvrTBHr0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QgBrcqtMHNUbz6oO1y+FuO2pqpQB33U3rMeoyVtZEsKVnhYi9xFTMRdm6VG1ap59S+Xt8zYYWsOHGXWehPQTIL4ES1xGmHytQkanf4YMgnnNE7pIWrbtyMc9v9JKFVPDcvc4PkYpyQ5KOY56vDRTIW7hu/0oGuk2bLFRdObpN38= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=qLFpEGvN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="qLFpEGvN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5F30C19425; Tue, 14 Apr 2026 16:50:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776185405; bh=Dge0DCS/QYtIgyrk1+RNGXNQhBsk1R+oQTAvvrTBHr0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qLFpEGvNOn2J0c3amth0T/BSS+qAPInX3J/3HfeiAHDkONa2ZuJWdBe2JmaB48Vsy 8yH51OyTrvDIOmka54WHeVakebbJVkeAn5lSkClMKw5rdVnpJMF7H8+02i/sxwXgCD 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" , Danilo Krummrich , Thierry Reding , Mikko Perttunen , David Airlie , Simona Vetter , Joerg Roedel , Will Deacon , Robin Murphy , Arnd Bergmann , Srinivas Kandagatla , Dmitry Baryshkov , Bharath Kumar , Chenna Kesava Raju , linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org, iommu@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> <20260414-computebus-v1-1-4d904d40926a@oss.qualcomm.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev 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> On Tue, Apr 14, 2026 at 10:01:15PM +0530, Ekansh Gupta via B4 Relay wrote: > From: Ekansh Gupta > > Introduce a new generic bus type for synthetic context bank devices > that require IOMMU context isolation. This bus provides a shared > infrastructure for accelerator and GPU drivers that create virtual > devices representing IOMMU context banks. > > Currently, drivers like host1x implement their own bus types for > context devices. This generic implementation allows multiple drivers > to share the same bus infrastructure, simplifying the IOMMU subsystem > integration and reducing code duplication. > > Signed-off-by: Ekansh Gupta > --- > drivers/base/Kconfig | 3 +++ > drivers/base/Makefile | 1 + > drivers/base/context_bus.c | 24 ++++++++++++++++++++++++ > include/linux/context_bus.h | 15 +++++++++++++++ > 4 files changed, 43 insertions(+) > > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig > index f7d385cbd3ba..479bc4bb442b 100644 > --- a/drivers/base/Kconfig > +++ b/drivers/base/Kconfig > @@ -4,6 +4,9 @@ menu "Generic Driver Options" > config AUXILIARY_BUS > bool > > +config CONTEXT_DEVICE_BUS > + bool So this is a context-free bus? I.e. no documentation? :) This feels really odd, this "bus" isn't doing anything at all. So why do you need it and can't use auxbus or faux? You say something about an iommu, but yet this has no information about an iommu at all, so why are they somehow special? You need to provide a lot more information here, sorry. greg k-h