linux-kernel - Re: [PATCH v2 2/2] pci, pcie-thunder-pem: Add PCIe host driver for ThunderX processors.

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Message-ID: <568AB788.6050605@caviumnetworks.com>
Date:	Mon, 4 Jan 2016 10:18:48 -0800
From:	David Daney <ddaney@...iumnetworks.com>
To:	Rob Herring <robh@...nel.org>
CC:	David Daney <ddaney.cavm@...il.com>,
	<linux-kernel@...r.kernel.org>, Will Deacon <will.deacon@....com>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<devicetree@...r.kernel.org>, Marc Zyngier <marc.zyngier@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	<linux-pci@...r.kernel.org>, Arnd Bergmann <arnd@...db.de>,
	David Daney <david.daney@...ium.com>
Subject: Re: [PATCH v2 2/2] pci, pcie-thunder-pem: Add PCIe host driver for
 ThunderX processors.

On 12/29/2015 12:37 PM, Rob Herring wrote:
> On Tue, Dec 22, 2015 at 03:43:52PM -0800, David Daney wrote:
>> From: David Daney <david.daney@...ium.com>
>>
>> Some Cavium ThunderX processors require quirky access methods for the
>> config space of the PCIe bridge.  Add a driver to provide these config
>> space accessor functions.  The pci-host-common code is used to
>> configure the PCI machinery.
>
> Same comments again...

Yes, I think your initial reply and my v2 must have crossed in 
mid-flight.  Then I was on holiday, but now I can respond...

>
>> Signed-off-by: David Daney <david.daney@...ium.com>
>> ---
>>   .../devicetree/bindings/pci/pcie-thunder-pem.txt   |  43 ++++
>>   drivers/pci/host/Kconfig                           |   7 +
>>   drivers/pci/host/Makefile                          |   1 +
>>   drivers/pci/host/pcie-thunder-pem.c                | 283 +++++++++++++++++++++
>>   4 files changed, 334 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/pci/pcie-thunder-pem.txt
>>   create mode 100644 drivers/pci/host/pcie-thunder-pem.c
>>
>> diff --git a/Documentation/devicetree/bindings/pci/pcie-thunder-pem.txt b/Documentation/devicetree/bindings/pci/pcie-thunder-pem.txt
>> new file mode 100644
>> index 0000000..52f56b3
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/pci/pcie-thunder-pem.txt
>> @@ -0,0 +1,43 @@
>> +* ThunderX PEM PCIe host controller
>> +
>> +Firmware-initialized PCIe host controller found on some Cavium
>> +ThunderX processors.
>> +
>> +The properties and their meanings are identical to those described in
>> +host-generic-pci.txt except as listed below.
>> +
>> +Properties of the host controller node that differ from
>> +host-generic-pci.txt:
>> +
>> +- compatible     : Must be "cavium,pci-host-thunder-pem"
>
> pcie rather than pci?

Technically it is a PCI host controller at the root, and doesn't become 
PCIe until we traverse a PCIe RC bridge,  Because of this, and also 
because there is deployed firmware supplying this compatible string, I 
would like to keep the name as is.

If you really want consistency, we could rename the driver (and this 
binding description file) to be pci-thunder-pem.

>
>> +
>> +- reg            : Two entries: First the configuration space for down
>> +                   stream devices base address and size, as accessed
>> +                   from the parent bus. Second, the register bank of
>> +                   the PEM device PCIe bridge.
>> +
>> +Example:
>> +
>> +    pem2 {
>
> pcie-controller@... instead of pem2.

That is purely cosmetic, as the names are not used for anything.  I can 
change it as you suggest.

[...]

Thanks,
David Daney
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