From: Catalin Marinas <catalin.marinas@arm.com>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: "Bjorn Helgaas" <bhelgaas@google.com>,
"Arnd Bergmann" <arnd@arndb.de>, "Marc Zyngier" <maz@kernel.org>,
"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Will Deacon" <will@kernel.org>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"Stephen Hemminger" <sthemmin@microsoft.com>,
"Wei Liu" <wei.liu@kernel.org>,
"Dexuan Cui" <decui@microsoft.com>,
"Rob Herring" <robh@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
linux-pci@vger.kernel.org,
"Sunil Muthuswamy" <sunilmut@microsoft.com>,
"Mike Rapoport" <rppt@kernel.org>
Subject: Re: [PATCH v6 4/8] arm64: PCI: Support root bridge preparation for Hyper-V
Date: Mon, 23 Aug 2021 10:43:44 +0100 [thread overview]
Message-ID: <20210823094343.GB8603@arm.com> (raw)
In-Reply-To: <20210726180657.142727-5-boqun.feng@gmail.com>
On Tue, Jul 27, 2021 at 02:06:53AM +0800, Boqun Feng wrote:
> Currently at root bridge preparation, the corresponding ACPI device will
> be set as the companion, however for a Hyper-V virtual PCI root bridge,
> there is no corresponding ACPI device, because a Hyper-V virtual PCI
> root bridge is discovered via VMBus rather than ACPI table. In order to
> support this, we need to make pcibios_root_bridge_prepare() work with
> cfg->parent being NULL.
>
> Use a NULL pointer as the ACPI device if there is no corresponding ACPI
> device, and this is fine because: 1) ACPI_COMPANION_SET() can work with
> the second parameter being NULL, 2) semantically, if a NULL pointer is
> set via ACPI_COMPANION_SET(), ACPI_COMPANION() (the read API for this
> field) will return NULL, and since ACPI_COMPANION() may return NULL, so
> users must have handled the cases where it returns NULL, and 3) since
> there is no corresponding ACPI device, it would be wrong to use any
> other value here.
>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
next prev parent reply other threads:[~2021-08-23 9:43 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 18:06 [PATCH v6 0/8] PCI: hv: Support host bridge probing on ARM64 Boqun Feng
2021-07-26 18:06 ` [PATCH v6 1/8] PCI: Introduce domain_nr in pci_host_bridge Boqun Feng
2021-07-26 18:06 ` [PATCH v6 2/8] PCI: Support populating MSI domains of root buses via bridges Boqun Feng
2021-07-27 16:14 ` Bjorn Helgaas
2021-07-26 18:06 ` [PATCH v6 3/8] arm64: PCI: Restructure pcibios_root_bridge_prepare() Boqun Feng
2021-08-23 9:43 ` Catalin Marinas
2021-07-26 18:06 ` [PATCH v6 4/8] arm64: PCI: Support root bridge preparation for Hyper-V Boqun Feng
2021-08-19 16:13 ` Boqun Feng
2021-08-20 17:49 ` Catalin Marinas
2021-08-23 9:12 ` Lorenzo Pieralisi
2021-08-23 9:43 ` Catalin Marinas [this message]
2021-07-26 18:06 ` [PATCH v6 5/8] PCI: hv: Generify PCI probing Boqun Feng
2021-07-26 18:06 ` [PATCH v6 6/8] PCI: hv: Set ->domain_nr of pci_host_bridge at probing time Boqun Feng
2021-07-26 18:06 ` [PATCH v6 7/8] PCI: hv: Set up MSI domain at bridge " Boqun Feng
2021-07-26 18:06 ` [PATCH v6 8/8] PCI: hv: Turn on the host bridge probing on ARM64 Boqun Feng
2021-08-03 17:14 ` Lorenzo Pieralisi
2021-08-09 14:38 ` Boqun Feng
2021-08-09 15:53 ` Lorenzo Pieralisi
2021-08-19 12:19 ` Boqun Feng
2021-07-27 16:12 ` [PATCH v6 0/8] PCI: hv: Support " Bjorn Helgaas
2021-08-02 8:13 ` Boqun Feng
2021-08-02 8:15 ` Boqun Feng
2021-08-02 23:05 ` Bjorn Helgaas
2021-08-19 14:17 ` Lorenzo Pieralisi
2021-08-19 15:47 ` Boqun Feng
2021-08-23 10:10 ` Lorenzo Pieralisi
2021-08-23 12:49 ` Boqun Feng
2021-08-23 10:02 ` Lorenzo Pieralisi
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