Re: [PATCH v6 8/8] PCI: hv: Turn on the host bridge probing on ARM64

From: Lorenzo Pieralisi <lorenzo.pieralisi@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>,
	"Catalin Marinas" <catalin.marinas@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 8/8] PCI: hv: Turn on the host bridge probing on ARM64
Date: Tue, 3 Aug 2021 18:14:51 +0100	[thread overview]
Message-ID: <20210803171451.GA15466@lpieralisi> (raw)
In-Reply-To: <20210726180657.142727-9-boqun.feng@gmail.com>

On Tue, Jul 27, 2021 at 02:06:57AM +0800, Boqun Feng wrote:
> Now we have everything we need, just provide a proper sysdata type for
> the bus to use on ARM64 and everything else works.
> 
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> ---
>  drivers/pci/controller/pci-hyperv.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index e6276aaa4659..62dbe98d1fe1 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -40,6 +40,7 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/pci.h>
> +#include <linux/pci-ecam.h>
>  #include <linux/delay.h>
>  #include <linux/semaphore.h>
>  #include <linux/irqdomain.h>
> @@ -448,7 +449,11 @@ enum hv_pcibus_state {
>  };
>  
>  struct hv_pcibus_device {
> +#ifdef CONFIG_X86
>  	struct pci_sysdata sysdata;
> +#elif defined(CONFIG_ARM64)
> +	struct pci_config_window sysdata;

This is ugly. HV does not need pci_config_window at all right
(other than arm64 pcibios_root_bridge_prepare()) ?

The issue is that in HV you have to have *some* sysdata != NULL, it is
just some data to retrieve the hv_pcibus_device.

Mmaybe we can rework ARM64 ACPI code to store the acpi_device in struct
pci_host_bridge->private instead of retrieving it from pci_config_window
so that we decouple HV from the ARM64 back-end.

HV would just set struct pci_host_bridge->private == NULL.

I need to think about this a bit, I don't think it should block
this series though but it would be nicer.

Lorenzo

> +#endif
>  	struct pci_host_bridge *bridge;
>  	struct fwnode_handle *fwnode;
>  	/* Protocol version negotiated with the host */
> @@ -3075,7 +3080,9 @@ static int hv_pci_probe(struct hv_device *hdev,
>  			 dom_req, dom);
>  
>  	hbus->bridge->domain_nr = dom;
> +#ifdef CONFIG_X86
>  	hbus->sysdata.domain = dom;
> +#endif
>  
>  	hbus->hdev = hdev;
>  	INIT_LIST_HEAD(&hbus->children);
> -- 
> 2.32.0
> 