linux-kernel - Re: [PATCH 2/2] PCI: iproc: Add optional brcm,pci-hotplug

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Date:   Thu, 10 Aug 2017 13:00:20 -0500
From:   Rob Herring <robh+dt@...nel.org>
To:     Oza Oza <oza.oza@...adcom.com>
Cc:     Ray Jui <ray.jui@...adcom.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        Jon Mason <jonmason@...adcom.com>,
        "bcm-kernel-feedback-list@...adcom.com" 
        <bcm-kernel-feedback-list@...adcom.com>,
        Andy Gospodarek <gospo@...adcom.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Oza Pawandeep <oza.pawandeep@...il.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 2/2] PCI: iproc: Add optional brcm,pci-hotplug

On Wed, Aug 9, 2017 at 12:52 AM, Oza Oza <oza.oza@...adcom.com> wrote:
> On Wed, Aug 9, 2017 at 11:13 AM, Oza Oza <oza.oza@...adcom.com> wrote:
>> On Wed, Aug 9, 2017 at 10:57 AM, Ray Jui <ray.jui@...adcom.com> wrote:
>>>
>>>
>>> On 8/8/2017 10:22 PM, Oza Oza wrote:
>>>>
>>>> On Tue, Aug 8, 2017 at 7:50 PM, Rob Herring <robh+dt@...nel.org> wrote:
>>>>>
>>>>> Please send bindings to DT list.
>>>>
>>>> Sure, will do that.
>>>>
>>>>> On Mon, Aug 7, 2017 at 11:44 PM, Oza Pawandeep <oza.oza@...adcom.com>
>>>>> wrote:
>>>>>>
>>>>>> Add description for optional device tree property
>>>>>> 'brcm,pci-hotplug' for PCI hotplug feature.
>>>>>>
>>>>>> Signed-off-by: Oza Pawandeep <oza.oza@...adcom.com>
>>>>>> Reviewed-by: Ray Jui <ray.jui@...adcom.com>
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt
>>>>>> b/Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt
>>>>>> index b8e48b4..a3bad24 100644
>>>>>> --- a/Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt
>>>>>> +++ b/Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt
>>>>>> @@ -72,6 +72,29 @@ Optional properties:
>>>>>>   - brcm,pcie-msi-inten: Needs to be present for some older iProc
>>>>>> platforms that
>>>>>>   require the interrupt enable registers to be set explicitly to enable
>>>>>> MSI
>>>>>>
>>>>>> +Optional properties:
>>>>>> +- brcm,pci-hotplug: PCI hotplug feature is supported.
>>>>>
>>>>> I think we should make this a common property. We already have
>>>>> "ibm,slot-pluggable", so I'd propose "slot-pluggable".
>>>>>
>>>>> There's also "hotpluggable" for memory nodes defined, so we could
>>>>> reuse that here.
>>>>>
>>>> ok I will rename this to
>>>> brcm,slot-pluggable
>>>
>>>
>>> How's brcm,slot-pluggable a common property? It's still brcm specific.
>>> Didn't Rob propose either "slot-pluggable" or "hotpluggable"?
>>>
>>> And note it goes to the generic PCI binding instead iProc PCIe specific
>>> binding.
>>>
>>
>> Initially I thought, Rob suggested either "slot-pluggable".
>> followed by, "hotpluggable" since memory node already has such property.

I didn't say which because I'm fine with either one. Pick the color of
the bikeshed.

>>
>> but not sure in which generic pci binding I should add ?
>> should it be part of
>> Documentation/devicetree/bindings/pci/host-generic-pci.txt

That's for generic CAM/ECAM hosts.

pci.txt would be the place.

>>
>> Can you please clarify Rob ?
>>
>> Regards,
>> Oza.
>
> To add, every SOC might have different way of implementing hotplug.
> so I suppose both the binding documents have to be updated.
>
> Documentation/devicetree/bindings/pci/host-generic-pci.txt
> which can have common boolean property
> named "hotpluggable"
>
> and SOC specific implementation can stay here
> for e.g.
> Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt
> brcm,prsnt-gpios

PRSNT# is a standard signal though, right? The h/w specific part would
be whether it is connected to GPIOs or the host controller has some
built-in controls. So yes, it should be documented if iproc-pcie uses
"prsnt-gpios", but it can still be a common property.

Rob