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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>

  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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