linux-kernel - Re: [PATCH V4 11/23] pci, acpi: Move ACPI host bridge device companion assignment to core code.

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Date:	Wed, 10 Feb 2016 22:09:34 +0100
From:	Tomasz Nowicki <tn@...ihalf.com>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:	bhelgaas@...gle.com, arnd@...db.de, will.deacon@....com,
	catalin.marinas@....com, rjw@...ysocki.net, hanjun.guo@...aro.org,
	okaya@...eaurora.org, jiang.liu@...ux.intel.com,
	Stefano.Stabellini@...citrix.com,
	robert.richter@...iumnetworks.com, mw@...ihalf.com,
	Liviu.Dudau@....com, ddaney@...iumnetworks.com,
	wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
	msalter@...hat.com, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-acpi@...ts.linaro.org,
	jchandra@...adcom.com, jcm@...hat.com
Subject: Re: [PATCH V4 11/23] pci, acpi: Move ACPI host bridge device
 companion assignment to core code.

On 02/09/2016 07:02 PM, Lorenzo Pieralisi wrote:
> On Thu, Feb 04, 2016 at 06:28:49PM +0100, Tomasz Nowicki wrote:
>> Currently we have two platforms (x86 & ia64) capable of PCI ACPI host
>> bridge initialization. They both use sysdata to pass down parent
>> device reference and both rely on NULL parent in pci_create_root_bus()
>> to validate sysdata content.
>>
>> It looks hacky and prevents us from getting some firmware specific
>> info for PCI host controller e.g. PCI bus domain number.
>> However, we overcome that blocker by passing down parent
>> device via pci_create_root_bus parameter (as the ACPI device type)
>> and using ACPI_COMPANION_SET in core code for ACPI boot method.
>> ACPI_COMPANION_SET is safe to run for all cases DT, ACPI and DT&ACPI.
>>
>> Suggested-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>> Signed-off-by: Tomasz Nowicki <tn@...ihalf.com>
>> Tested-by: Duc Dang <dhdang@....com>
>> Tested-by: Dongdong Liu <liudongdong3@...wei.com>
>> Tested-by: Hanjun Guo <hanjun.guo@...aro.org>
>> Tested-by: Graeme Gregory <graeme.gregory@...aro.org>
>> Tested-by: Sinan Kaya <okaya@...eaurora.org>
>> ---
>>   drivers/acpi/pci_root.c | 5 ++++-
>>   drivers/pci/probe.c     | 2 ++
>>   2 files changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index ae3fe4e..a65c8c2 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -846,7 +846,10 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
>>   
>>   	pci_acpi_root_add_resources(info);
>>   	pci_add_resource(&info->resources, &root->secondary);
>> -	bus = pci_create_root_bus(NULL, busnum, ops->pci_ops,
>> +
>> +	/* Root bridge device needs to be sure of parent ACPI type */
> You can improve the comment.
>
> "pci_create_root_bus() needs to detect the parent device type,
> so initialize its companion data accordingly".
Agree, I will change comment.
>
>> +	ACPI_COMPANION_SET(&device->dev, device);
>> +	bus = pci_create_root_bus(&device->dev, busnum, ops->pci_ops,
>>   				  sysdata, &info->resources);
>>   	if (!bus)
>>   		goto out_release_info;
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index 6d7ab9b..81dd3a2 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -2100,6 +2100,8 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>>   	bridge->dev.parent = parent;
>>   	bridge->dev.release = pci_release_host_bridge_dev;
>>   	dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
>> +	ACPI_COMPANION_SET(&bridge->dev,
>> +			   parent ? to_acpi_device_node(parent->fwnode) : NULL);
> if (parent)
> 	ACPI_COMPANION_SET(&bridge->dev, ACPI_COMPANION(parent));
>
> ?
Looks better.
>
> It seems fine to me, hopefully Rafael can have a look to countercheck.
>
> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Thanks,
Tomasz