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From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Hanjun Guo <guohanjun@huawei.com>
Cc: devicetree@vger.kernel.org, Sudeep Holla <sudeep.holla@arm.com>,
	Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
	linux-pci@vger.kernel.org,
	Diana Craciun <diana.craciun@oss.nxp.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	iommu@lists.linux-foundation.org, linux-acpi@vger.kernel.org,
	Makarand Pawagi <makarand.pawagi@nxp.com>,
	Rob Herring <robh+dt@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Robin Murphy <robin.murphy@arm.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 01/12] ACPI/IORT: Make iort_match_node_callback walk the ACPI namespace for NC
Date: Thu, 9 Jul 2020 10:21:56 +0100
Message-ID: <20200709092156.GB18149@e121166-lin.cambridge.arm.com> (raw)
In-Reply-To: <0cbd1da8-e283-7e13-d2b3-4d14775fd870@huawei.com>

On Thu, Jul 02, 2020 at 04:22:00PM +0800, Hanjun Guo wrote:
> Hi Robin,
> 
> On 2020/7/2 0:12, Robin Murphy wrote:
> > On 2020-06-30 14:04, Hanjun Guo wrote:
> > > On 2020/6/30 18:24, Lorenzo Pieralisi wrote:
> > > > On Tue, Jun 30, 2020 at 11:06:41AM +0800, Hanjun Guo wrote:
> > > > 
> > > > [...]
> > > > 
> > > > > > For devices that aren't described in the DSDT - IORT translations
> > > > > > are determined by their ACPI parent device. Do you see/Have you
> > > > > > found any issue with this approach ?
> > > > > 
> > > > > The spec says "Describes the IO relationships between devices
> > > > > represented in the ACPI namespace.", and in section 3.1.1.3 Named
> > > > > component node, it says:
> > > > 
> > > > PCI devices aren't necessarily described in the ACPI namespace and we
> > > > still use IORT to describe them - through the RC node.
> > > > 
> > > > > "Named component nodes are used to describe devices that are also
> > > > > included in the Differentiated System Description Table (DSDT). See
> > > > > [ACPI]."
> > > > > 
> > > > > So from my understanding, the IORT spec for now, can only do ID
> > > > > translations for devices in the DSDT.
> > > > 
> > > > I think you can read this multiple ways but this patch does not
> > > > change this concept. What changes, is applying parent's node IORT
> > > > mapping to child nodes with no associated DSDT nodes, it is the
> > > > same thing we do with PCI and the _DMA method - we could update
> > > > the wording in the specs if that clarifies but I don't think this
> > > > deliberately disregards the specifications.
> > > 
> > > I agree, but it's better to update the wording of the spec.
> > > 
> > > > 
> > > > > > > For a platform device, if I use its parent's full path name for
> > > > > > > its named component entry, then it will match, but this will violate
> > > > > > > the IORT spec.
> > > > > > 
> > > > > > Can you elaborate on this please I don't get the point you
> > > > > > are making.
> > > > > 
> > > > > For example, device A is not described in DSDT so can't represent
> > > > > as a NC node in IORT. Device B can be described in DSDT and it
> > > > > is the parent of device A, so device B can be represented in IORT
> > > > > with memory access properties and node flags with Substream width
> > > > > and Stall supported info.
> > > > > 
> > > > > When we trying to translate device A's ID, we reuse all the memory
> > > > > access properties and node flags from its parent (device B), but
> > > > > will it the same?
> > > > 
> > > > I assume so why wouldn't it be ? Why would be describe them in
> > > > a parent-child relationship if that's not how the system looks like
> > > > in HW ?
> > > 
> > > The point I'm making is that I'm not sure all the memory access and
> > > stall properties are the same for the parent and the device itself.
> > 
> > Is that even a valid case though? The principal thing we want to
> > accommodate here is when device B *is* the one accessing memory, either
> > because it is a bridge with device A sat behind it, or because device A
> > is actually just some logical function or subset of physical device B.
> 
> Thanks for the clarify, for CCA attributes, child device should be the
> same as its parent and that was written in the ACPI spec, so it's better
> to make it clear for other properties in the spec as well.
> 
> > 
> > If the topology is such that device A is a completely independent device
> > with its own path to memory such that it could have different
> > properties, I would expect that it *should* be described in DSDT, and I
> > can't easily think of a good reason why it wouldn't be. I'm also
> > struggling to imagine how it might even have an ID that had to be
> > interpreted in the context of device B if it wasn't one of the cases
> > above :/
> > 
> > I don't doubt that people could - or maybe even have - come up with crap
> > DSDT bindings that don't represent the hardware sufficiently accurately,
> > but I'm not sure that should be IORT's problem...
> 
> As I said in previous email, I'm not against this patch, and seems
> have no regressions for platforms that using named component node
> such as D05/D06 (I will test it shortly to make sure), but it's better
> to update the wording of the spec (even after this patch set is merged).

Have you managed to test this series ?

Thanks,
Lorenzo
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Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-21 12:59 [PATCH 00/12] ACPI/OF: Upgrade MSI/IOMMU ID mapping APIs Lorenzo Pieralisi
2020-05-21 12:59 ` [PATCH 01/12] ACPI/IORT: Make iort_match_node_callback walk the ACPI namespace for NC Lorenzo Pieralisi
2020-05-21 12:59 ` [PATCH 02/12] ACPI/IORT: Make iort_get_device_domain IRQ domain agnostic Lorenzo Pieralisi
2020-05-21 19:56   ` Bjorn Helgaas
2020-05-21 12:59 ` [PATCH 03/12] ACPI/IORT: Make iort_msi_map_rid() PCI agnostic Lorenzo Pieralisi
2020-05-21 13:00 ` [PATCH 04/12] ACPI/IORT: Remove useless PCI bus walk Lorenzo Pieralisi
2020-05-21 13:00 ` [PATCH 05/12] ACPI/IORT: Add an input ID to acpi_dma_configure() Lorenzo Pieralisi
2020-05-21 13:00 ` [PATCH 06/12] of/iommu: Make of_map_rid() PCI agnostic Lorenzo Pieralisi
2020-05-21 22:47   ` Rob Herring
2020-06-04 14:27     ` Lorenzo Pieralisi
2020-05-21 13:00 ` [PATCH 07/12] of/device: Add input id to of_dma_configure() Lorenzo Pieralisi
2020-05-21 23:02   ` Rob Herring
2020-06-04 14:49     ` Lorenzo Pieralisi
2020-05-21 13:00 ` [PATCH 08/12] of/irq: make of_msi_map_get_device_domain() bus agnostic Lorenzo Pieralisi
2020-05-21 19:57   ` Bjorn Helgaas
2020-05-21 13:00 ` [PATCH 09/12] dt-bindings: arm: fsl: Add msi-map device-tree binding for fsl-mc bus Lorenzo Pieralisi
2020-05-21 23:10   ` Rob Herring
2020-05-22  9:42     ` Robin Murphy
2020-05-22  9:57       ` Diana Craciun OSS
2020-05-22 14:08         ` Rob Herring
2020-05-22 14:34           ` Robin Murphy
2020-05-22 14:02       ` Rob Herring
2020-05-22 15:38         ` Laurentiu Tudor
2020-05-21 13:00 ` [PATCH 10/12] of/irq: Make of_msi_map_rid() PCI bus agnostic Lorenzo Pieralisi
2020-05-21 23:17   ` Rob Herring
2020-06-04 15:08     ` Lorenzo Pieralisi
2020-05-21 13:00 ` [PATCH 11/12] bus/fsl-mc: Refactor the MSI domain creation in the DPRC driver Lorenzo Pieralisi
2020-05-21 13:00 ` [PATCH 12/12] bus: fsl-mc: Add ACPI support for fsl-mc Lorenzo Pieralisi
2020-05-21 15:03   ` Laurentiu Tudor
2020-05-22  5:32     ` Makarand Pawagi
2020-05-22  9:53       ` Lorenzo Pieralisi
2020-06-19  8:20 ` [PATCH v2 00/12] ACPI/OF: Upgrade MSI/IOMMU ID mapping APIs Lorenzo Pieralisi
2020-06-19  8:20   ` [PATCH v2 01/12] ACPI/IORT: Make iort_match_node_callback walk the ACPI namespace for NC Lorenzo Pieralisi
2020-06-29  4:24     ` Hanjun Guo
2020-06-29  9:05       ` Lorenzo Pieralisi
2020-06-30  3:06         ` Hanjun Guo
2020-06-30 10:24           ` Lorenzo Pieralisi
2020-06-30 13:04             ` Hanjun Guo
2020-07-01 16:12               ` Robin Murphy
2020-07-02  8:22                 ` Hanjun Guo
2020-07-09  9:21                   ` Lorenzo Pieralisi [this message]
2020-07-09 12:48                     ` Hanjun Guo
2020-08-18  0:49                   ` Hanjun Guo
2020-06-19  8:20   ` [PATCH v2 02/12] ACPI/IORT: Make iort_get_device_domain IRQ domain agnostic Lorenzo Pieralisi
2020-06-19  8:20   ` [PATCH v2 03/12] ACPI/IORT: Make iort_msi_map_rid() PCI agnostic Lorenzo Pieralisi
2020-07-15  9:15     ` Lorenzo Pieralisi
2020-07-21 14:59     ` Bjorn Helgaas
2020-07-27  6:06       ` [EXT] " Makarand Pawagi
2020-06-19  8:20   ` [PATCH v2 04/12] ACPI/IORT: Remove useless PCI bus walk Lorenzo Pieralisi
2020-06-19  8:20   ` [PATCH v2 05/12] ACPI/IORT: Add an input ID to acpi_dma_configure() Lorenzo Pieralisi
2020-07-09  9:35     ` Lorenzo Pieralisi
2020-07-15  9:13       ` Lorenzo Pieralisi
2020-07-28 12:48         ` Lorenzo Pieralisi
2020-07-28 13:00           ` Rafael J. Wysocki
2020-06-19  8:20   ` [PATCH v2 06/12] of/iommu: Make of_map_rid() PCI agnostic Lorenzo Pieralisi
2020-06-22 13:26     ` Joerg Roedel
2020-07-13 23:57     ` Rob Herring
2020-06-19  8:20   ` [PATCH v2 07/12] of/device: Add input id to of_dma_configure() Lorenzo Pieralisi
2020-06-30 21:50     ` Rob Herring
2020-06-19  8:20   ` [PATCH v2 08/12] dt-bindings: arm: fsl: Add msi-map device-tree binding for fsl-mc bus Lorenzo Pieralisi
2020-06-30 21:55     ` Rob Herring
2020-06-19  8:20   ` [PATCH v2 09/12] of/irq: make of_msi_map_get_device_domain() bus agnostic Lorenzo Pieralisi
2020-06-30 21:50     ` Rob Herring
2020-06-19  8:20   ` [PATCH v2 10/12] of/irq: Make of_msi_map_rid() PCI " Lorenzo Pieralisi
2020-06-30 21:56     ` Rob Herring
2020-06-19  8:20   ` [PATCH v2 11/12] bus/fsl-mc: Refactor the MSI domain creation in the DPRC driver Lorenzo Pieralisi
2020-07-15 13:05     ` Marc Zyngier
2020-06-19  8:20   ` [PATCH v2 12/12] bus: fsl-mc: Add ACPI support for fsl-mc Lorenzo Pieralisi
2020-07-01 16:55     ` Laurentiu Tudor
2020-07-09  9:19       ` Lorenzo Pieralisi
2020-07-09  9:26         ` [EXT] " Makarand Pawagi
2020-07-09 10:14           ` Laurentiu Tudor
2020-07-09 10:37             ` Makarand Pawagi
2020-07-09 10:39               ` Laurentiu Tudor
2020-07-09 10:47               ` Diana Craciun OSS
2020-07-09 10:52                 ` Makarand Pawagi
2020-07-15 10:06                   ` Lorenzo Pieralisi
2020-07-16  3:23                     ` Makarand Pawagi
2020-07-16  7:57                       ` Marc Zyngier
2020-07-20 16:54   ` [PATCH v2 00/12] ACPI/OF: Upgrade MSI/IOMMU ID mapping APIs Lorenzo Pieralisi
2020-07-21  4:28     ` [EXT] " Makarand Pawagi
2020-07-28 17:01   ` Catalin Marinas

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