linux-kernel - Re: [PATCH 0/4] Driver for talking to PLX PEX8xxx PCIe switch over I2C

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Date:	Tue, 30 Sep 2014 14:45:37 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Rajat Jain <rajatxjain@...il.com>
Cc:	Jiri Kosina <jkosina@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-i2c <linux-i2c@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	Rajat Jain <rajatjain@...iper.net>,
	Guenter Roeck <groeck@...iper.net>,
	Wolfram Sang <wsa@...-dreams.de>
Subject: Re: [PATCH 0/4] Driver for talking to PLX PEX8xxx PCIe switch over I2C

[+cc Wolfram]

On Mon, Sep 29, 2014 at 10:46 PM, Rajat Jain <rajatxjain@...il.com> wrote:
> Most of the PLX PCI Express switches (and also switches from other vendors such
> IDT) provide an I2C based secondary interface to access and program the switch.
> This can be used to program the switch in situations where the PCIe interface
> may not be suitable, or even available. (For instance, we may need to program
> the device in a particular fashion before we even begin enumerating on the PCI,
> or to even enable the PCIe interface of the device). More information on
> usecases and other details has been provided in the documentation being added
> as part of this patchset.
>
> This is a driver that allows talking to the PLX PEX8xxx family of PCIe switches
> over its I2C interface. Here are the patch descriptions:
>
> [Patch 1/4] - Adds the PEX8xxx driver that exports API calls to read / write.
> [Patch 2/4] - Adds a sysfs interface, to allow access to the switch.
> [Patch 3/4] - Adds the MAINTAINERS entry.
> [Patch 4/4] - Adds the documentation in Documentation/PCI/pex8xxx_i2c.txt
>
> Since this is a driver for a PCIe switch, I currently put it under /driver/pci/.
> I'm very open to suggestions for moving this around (Does introducing
> drivers/pci/switch/ seem any better?). Especially I can see that the
> drivers/pci/Kconfig appears under "Bus Options" in the main menu which does not
> look like the right place for this driver. I am looking for suggestions here.

Definitely interesting work.  I have no idea where to put it.  It
doesn't have anything to do with PCI core services or structures, so
drivers/pci doesn't seem like the ideal place for it, but I don't have
any better ideas.  If it did end up under drivers/pci, I agree that a
drivers/pci/switch or something similar would probably be better than
having it directly in drivers/pci.

Maybe Wolfram or other I2C folks will have an idea.

> Rajat Jain (4):
>   pci: Add I2C driver for the PLX PEX8xxx PCIe switch
>   pci/pex8xxx: Add sysfs interface for userspace access.
>   MAINTAINERS: Add new device driver entry for PEX pex8xxx
>   Documentation: Add documentation for the PCI switch PEX8xxx I2C
>     driver
>
>  Documentation/PCI/pex8xxx_i2c.txt |  134 +++++++++
>  MAINTAINERS                       |    7 +
>  drivers/pci/Kconfig               |   13 +
>  drivers/pci/Makefile              |    2 +
>  drivers/pci/pex8xxx_i2c.c         |  538 +++++++++++++++++++++++++++++++++++++
>  include/linux/i2c/pex8xxx_i2c.h   |   36 +++
>  6 files changed, 730 insertions(+)
>  create mode 100644 Documentation/PCI/pex8xxx_i2c.txt
>  create mode 100644 drivers/pci/pex8xxx_i2c.c
>  create mode 100644 include/linux/i2c/pex8xxx_i2c.h
>
> --
> 1.7.9.5
>
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