From: Robin Murphy <robin.murphy@arm.com>
To: Hanjun Guo <guohanjun@huawei.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: devicetree@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
linux-pci@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Diana Craciun <diana.craciun@oss.nxp.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Makarand Pawagi <makarand.pawagi@nxp.com>,
linux-acpi@vger.kernel.org, iommu@lists.linux-foundation.org,
Rob Herring <robh+dt@kernel.org>,
Sudeep Holla <sudeep.holla@arm.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Will Deacon <will@kernel.org>,
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: Wed, 1 Jul 2020 17:12:35 +0100 [thread overview]
Message-ID: <952a6720-f401-1441-5548-5b40cfc76d3a@arm.com> (raw)
In-Reply-To: <4817d766-0437-5356-a0b9-97b111d4cae2@huawei.com>
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.
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...
Robin.
>> Do you have a specific example in mind that we should be aware of ?
>>
>>> So the IORT spec don't support this, at least it's pretty vague
>>> I think.
>>
>> I think that's a matter of wording, it can be updated if it needs be,
>> reach out if you see any issue with the current approach please.
>
> If the all the properties for parent and device itself are the same,
> I have no strong opinion for this patch, but it's better to update
> the wording of the spec as well.
>
> Thanks
> Hanjun
>
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next prev parent reply other threads:[~2020-07-01 16:12 UTC|newest]
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 [this message]
2020-07-02 8:22 ` Hanjun Guo
2020-07-09 9:21 ` Lorenzo Pieralisi
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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