Re: [PATCHv2] PCI: QDF2432 32 bit config space accessors

[Sinan Kaya]

Hi Bjorn,

On 11/2/2016 12:08 PM, Bjorn Helgaas wrote:
> On Tue, Nov 01, 2016 at 07:06:31AM -0600, cov@xxxxxxxxxxxxxx wrote:
>> Hi Bjorn,
>>
>> On 2016-10-31 15:48, Bjorn Helgaas wrote:
>>> On Wed, Sep 21, 2016 at 06:38:05PM -0400, Christopher Covington wrote:
>>>> The Qualcomm Technologies QDF2432 SoC does not support accesses
>>>> smaller
>>>> than 32 bits to the PCI configuration space. Register the appropriate
>>>> quirk.
>>>>
>>>> Signed-off-by: Christopher Covington <cov@xxxxxxxxxxxxxx>
>>>
>>> Hi Christopher,
>>>
>>> Can you rebase this against v4.9-rc1?  It no longer applies to my tree.
>>
>> I apologize for not being clearer. This patch depends on:
>>
>> PCI/ACPI: Extend pci_mcfg_lookup() responsibilities
>> PCI/ACPI: Check platform-specific ECAM quirks
>>
>> These patches from Tomasz Nowicki were previously in your pci/ecam-v6
>> branch, but that seems to have come and gone. How would you like to
>> proceed?
> 
> Oh yes, that's right, I forgot that connection.  I'm afraid I kind of
> dropped the ball on that thread, so I went back and read through it
> again.
> 
> I *think* the current state is:
> 
>   - I'm OK with the first two patches that add the quirk
>     infrastructure.
> 
>   - My issue with the last three patches that add ThunderX quirks is
>     that there's no generic description of the ECAM address space.
> 
> So if I understand correctly, your Qualcomm patch depends only on the
> first two patches.
> 
> Then the question is how the Qualcomm ECAM address space is described.
> Your quirk overrides the default pci_generic_ecam_ops with the
> &pci_32b_ops, but it doesn't touch the address space part, so I assume
> the bus ranges and corresponding address space in your MCFG is
> correct.  So far, so good.

Qualcomm ECAM space includes both the root port and the endpoint address
space with a single contiguous 256 MB address space described in MCFG table.
There is no need to describe additional resources like PNP0C02.

The only thing we missed was 8/16 bits access support on the root port.
That's why, we need Cov's patch.

> 
> Is there also an ACPI device that contains that space in _CRS?  I
> think we concluded that the standard solution is to describe this with
> a PNP0C02 device.
> 
> Would you mind opening a bugzilla at bugzilla.kernel.org and attaching
> the dmesg log, /proc/iomem, and maybe a DSDT dump?  I'd like to have
> something to point at to say "if you need an MCFG quirk, you need the
> MCFG bit and *also* these other related ACPI device bits, and here's
> how it should be done."
> 
> Bjorn
> 


-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.