Re: [Devel] Error in documentation of AcpiOsDerivePciId?

[Moore, Robert <robert.moore at intel.com>]

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Yes, It looks like there may be more to this than it first appeared. I haven't looked at the DerivePciId interface for some time.

I'm not fully sure what RegionObj->Region.Node refers to. I will investigate further.

Bob

>-----Original Message-----
>From: Grégoire Sutre [mailto:gregoire.sutre(a)gmail.com]
>Sent: Tuesday, April 20, 2010 9:07 AM
>To: Moore, Robert
>Cc: devel(a)acpica.org
>Subject: Re: [Devel] Error in documentation of AcpiOsDerivePciId?
>
>Hi Robert,
>
>First I want to thank you for your answer.
>
>> It looks to me that the documentation (ACPICA programmer reference) is
>correct.
>>
>> However, the acpiosxf.h file uses names that don't match the
>documentation and are not very descriptive.
>>
>> The ACPICA code uses a variable named "PciRootNode" for the
>"DeviceHandle" parameter, that is ok.
>
>The call to AcpiOsDerivePciId that I mentioned is performed in the
>function AcpiEvPciConfigRegionSetup of events/evrgnini.c.  Looking at
>this function (from acpica unix source code release 20100331), I see
>that:
>
>- RegionObj->Region.Node is the PCI device node that we are interested
>   in.  This is confirmed by the part that finds the parent device
>   object, which starts with:
>   PciDeviceNode = RegionObj->Region.Node;
>
>- PciRootNode is the PCI root bridge upstream of the PCI device node
>   that we are interested in.  Indeed, there is a while-loop that walks
>   the ancestors of the PCI device node until a PCI root bridge is found,
>   iteratively assigning PciRootNode to these ancestors.  See lines 312
>   to 360.
>
>This is the reason why I believe that in the call
>
>AcpiOsDerivePciId (PciRootNode, RegionObj->Region.Node, &PciId);
>
>- PciRootNode is not a handle to the PCI device, it is a handle to its
>   upstream PCI root bridge, and
>- RegionObj->Region.Node is a handle to the PCI device.
>
>>> So it seems to me that the correct arguments for AcpiOsDerivePciId are:
>>
>>> AcpiOsDerivePciId(
>>>    ACPI_HANDLE		PciRootHandle
>>>    ACPI_HANDLE		DeviceHandle
>>>    ACPI_PCI_ID		**PciId)
>>
>>
>> No, I don't think so. The second parameter is a handle to a region
>object.
>
>In the above call to AcpiOsDerivePciId, the second parameter, which is
>RegionObj->Region.Node, is of type (ACPI_NAMESPACE_NODE *).  I'm not
>familiar with all the ACPI types, but I guess that this type is not for
>region objects.
>
>Note that the implementation of AcpiOsDerivePciId in the linux kernel
>(as well as in the freebsd and netbsd kernels) seem to understand its
>interface in the same way as I did.
>
>http://lxr.linux.no/#linux+v2.6.33/drivers/acpi/osl.c#L689
>
>Best regards,
>
>Grégoire
>
>>> -----Original Message-----
>>> From: devel-bounces(a)acpica.org [mailto:devel-bounces(a)acpica.org] On
>Behalf
>>> Of Grégoire Sutre
>>> Sent: Tuesday, April 20, 2010 2:46 AM
>>> To: devel(a)acpica.org
>>> Subject: [Devel] Error in documentation of AcpiOsDerivePciId?
>>>
>>> Hi list,
>>>
>>> According to the ACPICA Programmer Reference, the function
>>> AcpiOsDerivePciId takes as arguments:
>>>
>>> AcpiOsDerivePciId(
>>>    ACPI_HANDLE		DeviceHandle
>>>    ACPI_HANDLE		PciRegionHandle
>>>    ACPI_PCI_ID		**PciId)
>>>
>>> with:
>>> - DeviceHandle:		a handle to the PCI device.
>>> - PciRegionHandle:	a handle the PCI configuration space operation
>>>                         region.
>>>
>>>
>>> However, the only call to AcpiOsDerivePciId in the ACPICA code, in
>>> events/evrgnini.c, is:
>>>
>>> AcpiOsDerivePciId (PciRootNode, RegionObj->Region.Node, &PciId);
>>>
>>> Moreover, the file include/acpiosxf.h contains:
>>>
>>> /*
>>>  * Interim function needed for PCI IRQ routing
>>>  */
>>> void
>>> AcpiOsDerivePciId(
>>>     ACPI_HANDLE             Rhandle,
>>>     ACPI_HANDLE             Chandle,
>>>     ACPI_PCI_ID             **PciId);
>>>
>>>
>>> So it seems to me that the correct arguments for AcpiOsDerivePciId are:
>>>
>>> AcpiOsDerivePciId(
>>>    ACPI_HANDLE		PciRootHandle
>>>    ACPI_HANDLE		DeviceHandle
>>>    ACPI_PCI_ID		**PciId)
>>>
>>> with:
>>> - PciRootHandle:	a handle the PCI root bridge upstream of the PCI
>>>                         device (or to the name space root node if no
>>>                         PCI root bridge was found in the ancestors).
>>> - DeviceHandle:		a handle to the PCI device.
>>>
>>>
>>> Is that correct?
>>>
>>> Thanks for your help,
>>>
>>> Grégoire
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