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From: Marc Zyngier <maz@kernel.org>
To: Mark Kettenis <mark.kettenis@xs4all.nl>
Cc: Rob Herring <robh@kernel.org>,
	devicetree@vger.kernel.org, alyssa@rosenzweig.io,
	kettenis@openbsd.org, tglx@linutronix.de, marcan@marcan.st,
	bhelgaas@google.com, jim2101024@gmail.com, nsaenz@kernel.org,
	f.fainelli@gmail.com, bcm-kernel-feedback-list@broadcom.com,
	daire.mcnamara@microchip.com, nsaenzjulienne@suse.de,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
	linux-rpi-kernel@lists.infradead.org
Subject: Re: [PATCH v4 3/4] dt-bindings: pci: Add DT bindings for apple,pcie
Date: Sun, 12 Sep 2021 21:13:17 +0100	[thread overview]
Message-ID: <8735q9d02q.wl-maz@kernel.org> (raw)
In-Reply-To: <561431b178447575@bloch.sibelius.xs4all.nl>

On Wed, 01 Sep 2021 12:29:22 +0100,
Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> 
> > Date: Tue, 31 Aug 2021 16:21:28 -0500
> > From: Rob Herring <robh@kernel.org>
> > 
> > On Fri, Aug 27, 2021 at 07:15:28PM +0200, Mark Kettenis wrote:
> > > From: Mark Kettenis <kettenis@openbsd.org>
> > > 
> > > The Apple PCIe host controller is a PCIe host controller with
> > > multiple root ports present in Apple ARM SoC platforms, including
> > > various iPhone and iPad devices and the "Apple Silicon" Macs.
> > > 
> > > Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
> > > ---
> > >  .../devicetree/bindings/pci/apple,pcie.yaml   | 165 ++++++++++++++++++
> > >  MAINTAINERS                                   |   1 +
> > >  2 files changed, 166 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/pci/apple,pcie.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/pci/apple,pcie.yaml b/Documentation/devicetree/bindings/pci/apple,pcie.yaml
> > > new file mode 100644
> > > index 000000000000..97a126db935a
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/pci/apple,pcie.yaml
> > > @@ -0,0 +1,165 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/pci/apple,pcie.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Apple PCIe host controller
> > > +
> > > +maintainers:
> > > +  - Mark Kettenis <kettenis@openbsd.org>
> > > +
> > > +description: |
> > > +  The Apple PCIe host controller is a PCIe host controller with
> > > +  multiple root ports present in Apple ARM SoC platforms, including
> > > +  various iPhone and iPad devices and the "Apple Silicon" Macs.
> > > +  The controller incorporates Synopsys DesigWare PCIe logic to
> > > +  implements its root ports.  But the ATU found on most DesignWare
> > > +  PCIe host bridges is absent.
> > > +
> > > +  All root ports share a single ECAM space, but separate GPIOs are
> > > +  used to take the PCI devices on those ports out of reset.  Therefore
> > > +  the standard "reset-gpios" and "max-link-speed" properties appear on
> > > +  the child nodes that represent the PCI bridges that correspond to
> > > +  the individual root ports.
> > > +
> > > +  MSIs are handled by the PCIe controller and translated into regular
> > > +  interrupts.  A range of 32 MSIs is provided.  These 32 MSIs can be
> > > +  distributed over the root ports as the OS sees fit by programming
> > > +  the PCIe controller's port registers.
> > > +
> > > +allOf:
> > > +  - $ref: /schemas/pci/pci-bus.yaml#
> > > +  - $ref: ../interrupt-controller/msi-controller.yaml#
> > > +
> > > +properties:
> > > +  compatible:
> > > +    items:
> > > +      - const: apple,t8103-pcie
> > > +      - const: apple,pcie
> > > +
> > > +  reg:
> > > +    minItems: 3
> > > +    maxItems: 5
> > > +
> > > +  reg-names:
> > > +    minItems: 3
> > > +    maxItems: 5
> > > +    items:
> > > +      - const: config
> > > +      - const: rc
> > > +      - const: port0
> > > +      - const: port1
> > > +      - const: port2
> > > +
> > > +  ranges:
> > > +    minItems: 2
> > > +    maxItems: 2
> > > +
> > > +  interrupts:
> > > +    description:
> > > +      Interrupt specifiers, one for each root port.
> > > +    minItems: 1
> > > +    maxItems: 3
> > > +
> > > +  msi-parent: true
> > 
> > I still think this should be dropped as it is meaningless with 
> > 'msi-controller' present.
> 
> Hmm.  As far as I can tell all current arm64 device trees that
> describe hardware with an MSI controller integrated on the PCI host
> bridge have both the 'msi-controller' and 'msi-parent' properties.
> See arch/arm64/boot/dts/marvell/aramada-37xx.dtsi and
> arch/arm64/boot/dts/xilinx/zynqmp.dtsi.
> 
> The current OpenBSD code will fail to map the MSIs if 'msi-parent'
> isn't there, although Linux seems to fall back on an MSI domain that's
> directly attached to the host bridge if the 'msi-parent' property is
> missing.  I think it makes sense to be explicit here, but if both you
> and Marc think it shouldn't be there, I probably can change the
> OpenBSD to do a similar fallback.

I think this matches the behaviour we have for interrupt-controller vs
interrupt-parent. I fail to see why msi-controller/msi-parent should
behave differently. And since there is an established OS that actually
requires this, I don't see how we can today make it illegal.

	M.

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

WARNING: multiple messages have this Message-ID
From: Marc Zyngier <maz@kernel.org>
To: Mark Kettenis <mark.kettenis@xs4all.nl>
Cc: Rob Herring <robh@kernel.org>,
	devicetree@vger.kernel.org, alyssa@rosenzweig.io,
	kettenis@openbsd.org, tglx@linutronix.de, marcan@marcan.st,
	bhelgaas@google.com, jim2101024@gmail.com, nsaenz@kernel.org,
	f.fainelli@gmail.com, bcm-kernel-feedback-list@broadcom.com,
	daire.mcnamara@microchip.com, nsaenzjulienne@suse.de,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
	linux-rpi-kernel@lists.infradead.org
Subject: Re: [PATCH v4 3/4] dt-bindings: pci: Add DT bindings for apple,pcie
Date: Sun, 12 Sep 2021 21:13:17 +0100	[thread overview]
Message-ID: <8735q9d02q.wl-maz@kernel.org> (raw)
In-Reply-To: <561431b178447575@bloch.sibelius.xs4all.nl>

On Wed, 01 Sep 2021 12:29:22 +0100,
Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> 
> > Date: Tue, 31 Aug 2021 16:21:28 -0500
> > From: Rob Herring <robh@kernel.org>
> > 
> > On Fri, Aug 27, 2021 at 07:15:28PM +0200, Mark Kettenis wrote:
> > > From: Mark Kettenis <kettenis@openbsd.org>
> > > 
> > > The Apple PCIe host controller is a PCIe host controller with
> > > multiple root ports present in Apple ARM SoC platforms, including
> > > various iPhone and iPad devices and the "Apple Silicon" Macs.
> > > 
> > > Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
> > > ---
> > >  .../devicetree/bindings/pci/apple,pcie.yaml   | 165 ++++++++++++++++++
> > >  MAINTAINERS                                   |   1 +
> > >  2 files changed, 166 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/pci/apple,pcie.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/pci/apple,pcie.yaml b/Documentation/devicetree/bindings/pci/apple,pcie.yaml
> > > new file mode 100644
> > > index 000000000000..97a126db935a
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/pci/apple,pcie.yaml
> > > @@ -0,0 +1,165 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/pci/apple,pcie.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Apple PCIe host controller
> > > +
> > > +maintainers:
> > > +  - Mark Kettenis <kettenis@openbsd.org>
> > > +
> > > +description: |
> > > +  The Apple PCIe host controller is a PCIe host controller with
> > > +  multiple root ports present in Apple ARM SoC platforms, including
> > > +  various iPhone and iPad devices and the "Apple Silicon" Macs.
> > > +  The controller incorporates Synopsys DesigWare PCIe logic to
> > > +  implements its root ports.  But the ATU found on most DesignWare
> > > +  PCIe host bridges is absent.
> > > +
> > > +  All root ports share a single ECAM space, but separate GPIOs are
> > > +  used to take the PCI devices on those ports out of reset.  Therefore
> > > +  the standard "reset-gpios" and "max-link-speed" properties appear on
> > > +  the child nodes that represent the PCI bridges that correspond to
> > > +  the individual root ports.
> > > +
> > > +  MSIs are handled by the PCIe controller and translated into regular
> > > +  interrupts.  A range of 32 MSIs is provided.  These 32 MSIs can be
> > > +  distributed over the root ports as the OS sees fit by programming
> > > +  the PCIe controller's port registers.
> > > +
> > > +allOf:
> > > +  - $ref: /schemas/pci/pci-bus.yaml#
> > > +  - $ref: ../interrupt-controller/msi-controller.yaml#
> > > +
> > > +properties:
> > > +  compatible:
> > > +    items:
> > > +      - const: apple,t8103-pcie
> > > +      - const: apple,pcie
> > > +
> > > +  reg:
> > > +    minItems: 3
> > > +    maxItems: 5
> > > +
> > > +  reg-names:
> > > +    minItems: 3
> > > +    maxItems: 5
> > > +    items:
> > > +      - const: config
> > > +      - const: rc
> > > +      - const: port0
> > > +      - const: port1
> > > +      - const: port2
> > > +
> > > +  ranges:
> > > +    minItems: 2
> > > +    maxItems: 2
> > > +
> > > +  interrupts:
> > > +    description:
> > > +      Interrupt specifiers, one for each root port.
> > > +    minItems: 1
> > > +    maxItems: 3
> > > +
> > > +  msi-parent: true
> > 
> > I still think this should be dropped as it is meaningless with 
> > 'msi-controller' present.
> 
> Hmm.  As far as I can tell all current arm64 device trees that
> describe hardware with an MSI controller integrated on the PCI host
> bridge have both the 'msi-controller' and 'msi-parent' properties.
> See arch/arm64/boot/dts/marvell/aramada-37xx.dtsi and
> arch/arm64/boot/dts/xilinx/zynqmp.dtsi.
> 
> The current OpenBSD code will fail to map the MSIs if 'msi-parent'
> isn't there, although Linux seems to fall back on an MSI domain that's
> directly attached to the host bridge if the 'msi-parent' property is
> missing.  I think it makes sense to be explicit here, but if both you
> and Marc think it shouldn't be there, I probably can change the
> OpenBSD to do a similar fallback.

I think this matches the behaviour we have for interrupt-controller vs
interrupt-parent. I fail to see why msi-controller/msi-parent should
behave differently. And since there is an established OS that actually
requires this, I don't see how we can today make it illegal.

	M.

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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-09-12 20:14 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-27 17:15 [PATCH v4 0/4] Apple M1 PCIe DT bindings Mark Kettenis
2021-08-27 17:15 ` Mark Kettenis
2021-08-27 17:15 ` [PATCH v4 1/4] dt-bindings: interrupt-controller: Convert MSI controller to json-schema Mark Kettenis
2021-08-27 17:15   ` Mark Kettenis
2021-08-27 19:15   ` Mark Kettenis
2021-08-27 19:15     ` Mark Kettenis
2021-08-31 21:04     ` Rob Herring
2021-08-31 21:04       ` Rob Herring
2021-08-31 20:57   ` Rob Herring
2021-08-31 20:57     ` Rob Herring
2021-09-01 10:56     ` Mark Kettenis
2021-09-01 10:56       ` Mark Kettenis
2021-08-31 20:58   ` Rob Herring
2021-08-31 20:58     ` Rob Herring
2021-08-27 17:15 ` [PATCH v4 2/4] dt-bindings: interrupt-controller: msi: Add msi-ranges property Mark Kettenis
2021-08-27 17:15   ` Mark Kettenis
2021-08-31 21:16   ` Rob Herring
2021-08-31 21:16     ` Rob Herring
2021-09-21 17:52     ` Mark Kettenis
2021-09-21 17:52       ` Mark Kettenis
2021-08-27 17:15 ` [PATCH v4 3/4] dt-bindings: pci: Add DT bindings for apple,pcie Mark Kettenis
2021-08-27 17:15   ` Mark Kettenis
2021-08-27 17:58   ` Alyssa Rosenzweig
2021-08-27 17:58     ` Alyssa Rosenzweig
2021-08-27 18:22     ` Mark Kettenis
2021-08-27 18:22       ` Mark Kettenis
2021-08-31 21:21   ` Rob Herring
2021-08-31 21:21     ` Rob Herring
2021-09-01 11:29     ` Mark Kettenis
2021-09-01 11:29       ` Mark Kettenis
2021-09-12 20:13       ` Marc Zyngier [this message]
2021-09-12 20:13         ` Marc Zyngier
2021-09-13 20:55         ` Rob Herring
2021-09-13 20:55           ` Rob Herring
2021-08-27 17:15 ` [PATCH v4 4/4] arm64: apple: Add PCIe node Mark Kettenis
2021-08-27 17:15   ` Mark Kettenis
2021-08-27 17:59   ` Alyssa Rosenzweig
2021-08-27 17:59     ` Alyssa Rosenzweig
2021-08-27 18:24     ` Mark Kettenis
2021-08-27 18:24       ` Mark Kettenis
2021-08-27 20:09       ` Alyssa Rosenzweig
2021-08-27 20:09         ` Alyssa Rosenzweig
2021-08-30 11:37   ` Marc Zyngier
2021-08-30 11:37     ` Marc Zyngier
2021-08-30 14:57     ` Mark Kettenis
2021-08-30 14:57       ` Mark Kettenis
2021-08-30 20:40       ` Marc Zyngier
2021-08-30 20:40         ` Marc Zyngier
2021-08-30 15:57     ` Rob Herring
2021-08-30 15:57       ` Rob Herring
2021-08-30 20:20       ` Marc Zyngier
2021-08-30 20:20         ` Marc Zyngier
2021-09-12 21:30   ` Marc Zyngier
2021-09-12 21:30     ` Marc Zyngier
2021-09-13 18:35     ` Mark Kettenis
2021-09-13 18:35       ` Mark Kettenis
2021-09-21 11:01 ` [PATCH v4 0/4] Apple M1 PCIe DT bindings Marc Zyngier
2021-09-21 11:01   ` Marc Zyngier

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