Received-SPF: pass (google.com: domain of linux-kernel+bounces-200944-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Tue, 04 Jun 2024 16:25:51 +0100
Message-ID: <86cyowlog0.wl-maz@kernel.org>
From: Marc Zyngier <maz@kernel.org>
To: Frank Li <Frank.li@nxp.com>
Cc: Robin Murphy <robin.murphy@arm.com>,	Bjorn Helgaas <helgaas@kernel.org>,
	Richard Zhu <hongxing.zhu@nxp.com>,	Lucas Stach <l.stach@pengutronix.de>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,	Krzysztof =?UTF-8?B?V2lsY3p5?=
 =?UTF-8?B?xYRza2k=?= <kw@linux.com>,	Rob Herring <robh@kernel.org>,	Bjorn
 Helgaas <bhelgaas@google.com>,	Shawn Guo <shawnguo@kernel.org>,	Sascha
 Hauer <s.hauer@pengutronix.de>,	Pengutronix Kernel Team
 <kernel@pengutronix.de>,	Fabio Estevam <festevam@gmail.com>,	NXP Linux Team
 <linux-imx@nxp.com>,	Philipp Zabel <p.zabel@pengutronix.de>,	Liam Girdwood
 <lgirdwood@gmail.com>,	Mark Brown <broonie@kernel.org>,	Manivannan
 Sadhasivam <manivannan.sadhasivam@linaro.org>,	Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@linaro.org>,	Conor Dooley <conor+dt@kernel.org>,
	linux-pci@vger.kernel.org,	imx@lists.linux.dev,
	linux-arm-kernel@lists.infradead.org,	linux-kernel@vger.kernel.org,
	bpf@vger.kernel.org,	devicetree@vger.kernel.org,	Will Deacon
 <will@kernel.org>,	Joerg Roedel <joro@8bytes.org>,	Jason Gunthorpe
 <jgg@ziepe.ca>,	Alyssa Rosenzweig <alyssa@rosenzweig.io>
Subject: Re: [PATCH v5 08/12] PCI: imx6: Config look up table(LUT) to support MSI ITS and IOMMU for i.MX95
In-Reply-To: <Zl4v10Od99et+tLX@lizhi-Precision-Tower-5810>
References: <20240603171921.GA685838@bhelgaas>
	<3d24fecf-1fdb-4804-9a51-d6c34a9d65c6@arm.com>
	<Zl4v10Od99et+tLX@lizhi-Precision-Tower-5810>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue)
 FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.2
 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO)
Precedence: bulk
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=US-ASCII

On Mon, 03 Jun 2024 22:04:23 +0100,
Frank Li <Frank.li@nxp.com> wrote:
> 
> iommu may share one stream id for multi-devices. but ITS MSI can't. each
> device's MSI index start from 0. It needs difference stream id for each
> device.

That's not quite true. We go through all sort of hoops to find about
device aliasing on PCI and allow devices that translate into the same
DID to get MSIs.

Of course, just like the IOMMU, you lose any form of isolation, but
you get what you pay for.

	M.

-- 
Without deviation from the norm, progress is not possible.