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Subject: Re: [PATCH 1/3] PCI: brcmstb: Break register definitions into
 separate header
To:     Jeremy Linton <jeremy.linton@arm.com>, linux-pci@vger.kernel.org
Cc:     lorenzo.pieralisi@arm.com, nsaenz@kernel.org, bhelgaas@google.com,
        rjw@rjwysocki.net, lenb@kernel.org, robh@kernel.org, kw@linux.com,
        bcm-kernel-feedback-list@broadcom.com, linux-acpi@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rpi-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20210805211200.491275-1-jeremy.linton@arm.com>
 <20210805211200.491275-2-jeremy.linton@arm.com>
 <f82761b1-fb7e-08b2-8bc3-c84d258e26d3@gmail.com>
 <ab2aa9e3-cdc7-1bc7-d493-8f3c991c3285@arm.com>
From:   Florian Fainelli <f.fainelli@gmail.com>
Message-ID: <ff7c598a-4c1d-7da0-f40a-f0c435e785d3@gmail.com>
Date:   Wed, 11 Aug 2021 01:39:52 -0700
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On 8/10/2021 8:10 AM, Jeremy Linton wrote:
> Hi,
> 
> Thanks for taking a look at this!
> 
> 
> On 8/10/21 5:07 AM, Florian Fainelli wrote:
>>
>>
>> On 8/5/2021 2:11 PM, Jeremy Linton wrote:
>>> We are about to create a standalone ACPI quirk module for the
>>> bcmstb controller. Lets move the register definitions into a separate
>>> file so they can be shared between the APCI quirk and the normal
>>> host bridge driver.
>>>
>>> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
>>> ---
>>>   drivers/pci/controller/pcie-brcmstb.c | 179 +------------------------
>>>   drivers/pci/controller/pcie-brcmstb.h | 182 ++++++++++++++++++++++++++
>>>   2 files changed, 183 insertions(+), 178 deletions(-)
>>>   create mode 100644 drivers/pci/controller/pcie-brcmstb.h
>>
>> You moved more than just register definitions into pcie-brcmstb.h you 
>> also moved internal structure definitions, enumerations, etc. which 
>> are not required since pcie-brcmstb-acpi.c does not access the 
>> brcm_pcie structure but open codes accesses to the MISC_STATUS 
>> register instead.
>>
>> There are no include guards added to this file (it is debatable 
>> whether we should add them), and it is also not covered by the 
>> existing BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE MAINTAINERS file 
>> entry.
> 
> Sure, I will reduce the .h to just the register definitions, guard it, 
> and tweak maintainers to cover pcie-brcmstb*.
> 
> 
>>
>> Given that there can be new platforms supported by this PCIe 
>> controller in the future possibly with the same limitations as the 
>> 2711, but with a seemingly different MISC_STATUS layout, you will have 
>> to think about a solution that scales, maybe we cross that bridge when 
>> we get there.
> 
> Yes, given I don't know what those changes are I can't predict how they 
> would have to be handled, or even if the platform would be a target of 
> the community maintaining the UEFI/ACPI port on the RPi. So punting on 
> that topic seems a reasonable solution at the moment. Better yet, more 
> of the linux community will see the advantage of the firmware interface 
> and this platform can utilize that method.

Ideally newer platforms would support ECAM and would not require a 
custom quirk if nothing else, we do have discussions about that right 
now, although it is not clear to me how it will materialize into a 
product that people can buy.
-- 
Florian