From: Robin Murphy <robin.murphy@arm.com>
To: Marc Zyngier <maz@kernel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Bjorn Helgaas <bhelgaas@google.com>
Cc: Frank Wunderlich <frank-w@public-files.de>,
Thierry Reding <treding@nvidia.com>,
Thomas Gleixner <tglx@linutronix.de>,
Rob Herring <robh@kernel.org>, Will Deacon <will@kernel.org>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Michael Kelley <mikelley@microsoft.com>,
Wei Liu <wei.liu@kernel.org>,
Thierry Reding <thierry.reding@gmail.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
Ryder Lee <ryder.lee@mediatek.com>,
Marek Vasut <marek.vasut+renesas@gmail.com>,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
Michal Simek <michal.simek@xilinx.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-hyperv@vger.kernel.org, linux-tegra@vger.kernel.org,
linux-mediatek@lists.infradead.org,
linux-renesas-soc@vger.kernel.org, kernel-team@android.com
Subject: Re: [PATCH v2 12/15] PCI/MSI: Let PCI host bridges declare their reliance on MSI domains
Date: Tue, 23 Mar 2021 11:45:02 +0000 [thread overview]
Message-ID: <6a2eaa5d-1d83-159f-69e5-c9e0a00a7b50@arm.com> (raw)
In-Reply-To: <20210322184614.802565-13-maz@kernel.org>
On 2021-03-22 18:46, Marc Zyngier wrote:
> The new 'no_msi' attribute solves the problem of advertising the lack
> of MSI capability for host bridges that know for sure that there will
> be no MSI for their end-points.
>
> However, there is a whole class of host bridges that cannot know
> whether MSIs will be provided or not, as they rely on other blocks
> to provide the MSI functionnality, using MSI domains. This is
> the case for example on systems that use the ARM GIC architecture.
>
> Introduce a new attribute ('msi_domain') indicating that implicit
> dependency, and use this property to set the NO_MSI flag when
> no MSI domain is found at probe time.
>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> drivers/pci/probe.c | 2 +-
> include/linux/pci.h | 1 +
> 2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 146bd85c037e..bac9f69a06a8 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -925,7 +925,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
> device_enable_async_suspend(bus->bridge);
> pci_set_bus_of_node(bus);
> pci_set_bus_msi_domain(bus);
> - if (bridge->no_msi)
> + if (bridge->no_msi || (bridge->msi_domain && !bus->dev.msi_domain))
> bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
>
> if (!parent)
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 48605cca82ae..d322d00db432 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -551,6 +551,7 @@ struct pci_host_bridge {
> unsigned int preserve_config:1; /* Preserve FW resource setup */
> unsigned int size_windows:1; /* Enable root bus sizing */
> unsigned int no_msi:1; /* Bridge has no MSI support */
> + unsigned int msi_domain:1; /* Bridge wants MSI domain */
Aren't these really the same thing? Either way we're saying the bridge
itself doesn't handle MSIs, it's just in one case we're effectively
encoding a platform-specific assumption that an external domain won't be
provided. I can't help wondering whether that distinction is really
necessary...
Robin.
>
> /* Resource alignment requirements */
> resource_size_t (*align_resource)(struct pci_dev *dev,
>
next prev parent reply other threads:[~2021-03-23 11:45 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 18:45 [PATCH v2 00/15] PCI/MSI: Getting rid of msi_controller, and other cleanups Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 01/15] PCI: tegra: Convert to MSI domains Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 02/15] PCI: rcar: Don't allocate extra memory for the MSI capture address Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 03/15] PCI: rcar: Convert to MSI domains Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 04/15] PCI: xilinx: Don't allocate extra memory for the MSI capture address Marc Zyngier
2021-03-24 12:35 ` Bharat Kumar Gogada
2021-03-24 12:55 ` Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 05/15] PCI: xilinx: Convert to MSI domains Marc Zyngier
2021-03-24 12:42 ` Bharat Kumar Gogada
2021-03-24 13:15 ` Marc Zyngier
2021-03-24 13:56 ` Bharat Kumar Gogada
2021-03-24 14:45 ` Marc Zyngier
2021-03-25 4:13 ` Bharat Kumar Gogada
2021-03-22 18:46 ` [PATCH v2 06/15] PCI: hv: Drop msi_controller structure Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 07/15] PCI/MSI: Drop use of msi_controller from core code Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 08/15] PCI/MSI: Kill msi_controller structure Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 09/15] PCI/MSI: Kill default_teardown_msi_irqs() Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 10/15] PCI/MSI: Let PCI host bridges declare their lack of MSI handling Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 11/15] PCI: mediatek: Advertise " Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 12/15] PCI/MSI: Let PCI host bridges declare their reliance on MSI domains Marc Zyngier
2021-03-23 11:45 ` Robin Murphy [this message]
2021-03-23 18:09 ` Marc Zyngier
2021-03-23 19:04 ` Robin Murphy
2021-03-24 13:19 ` Lorenzo Pieralisi
2021-03-24 16:11 ` Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 13/15] PCI/MSI: Make pci_host_common_probe() declare its " Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 14/15] PCI/MSI: Document the various ways of ending up with NO_MSI Marc Zyngier
2021-03-22 18:46 ` [PATCH v2 15/15] PCI: Refactor HT advertising of NO_MSI flag Marc Zyngier
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