Re: [RFC PATCHv2 1/2] Export SoC info through sysfs

[Greg KH <greg@kroah.com>]

On Fri, Mar 11, 2011 at 07:58:16PM +0200, Eduardo Valentin wrote:
> Hello,
> 
> On Fri, Mar 11, 2011 at 07:52:57AM -0800, ext Greg KH wrote:
> > On Fri, Mar 11, 2011 at 03:32:51PM +0100, Arnd Bergmann wrote:
> > > On Friday 11 March 2011, Maxime Coquelin wrote:
> > > > Common base to export System-on-Chip related informations through sysfs.
> > > > 
> > > > Creation of a "socinfo" directory under /sys/.
> > > > Creation of SoC information entries.
> > > > 
> > > > Signed-off-by: Maxime COQUELIN <maxime.coquelin-nonst@stericsson.com>
> > > 
> > > I think it's better than the previous patch to create an
> > > artificial device in /sys/devices/system/socinfo, but I'd
> > > still prefer the information to be attached to a real device
> > > that represents the SOC, as I explained in the discussion with
> > > Linus Walleij.
> > > 
> > > You should definitely add Greg on Cc, as he's maintaining sysfs
> > > and certainly has an opininion here.
> > > 
> > > 	Arnd
> > > 
> > > > ---
> > > >  Documentation/ABI/testing/sysfs-socinfo |   16 ++++++
> > > >  drivers/base/Kconfig                    |    3 +
> > > >  drivers/base/Makefile                   |    1 +
> > > >  drivers/base/soc.c                      |   79 +++++++++++++++++++++++++++++++
> > > >  include/linux/sys_soc.h                 |   50 +++++++++++++++++++
> > > >  5 files changed, 149 insertions(+), 0 deletions(-)
> > > >  create mode 100644 Documentation/ABI/testing/sysfs-socinfo
> > > >  create mode 100644 drivers/base/soc.c
> > > >  create mode 100644 include/linux/sys_soc.h
> > > > 
> > > > diff --git a/Documentation/ABI/testing/sysfs-socinfo b/Documentation/ABI/testing/sysfs-socinfo
> > > > new file mode 100644
> > > > index 0000000..afd9da2
> > > > --- /dev/null
> > > > +++ b/Documentation/ABI/testing/sysfs-socinfo
> > > > @@ -0,0 +1,16 @@
> > > > +What:		/sys/socinfo
> > > > +Date:		March 2011
> > > > +contact:	Maxime Coquelin <maxime.coquelin-nonst@stericsson.com>
> > > > +Description:
> > > > +		The /sys/socinfo directory contains information about the
> > > > +		System-on-Chip.	It is only available if platform implements it.
> > > > +		This directory contains two kind of attributes :
> > > > +			- common attributes: 
> > > > +				* machine: the name of the machine.
> > > > +				* family: the family name of the SoC
> > > > +			- SoC-specific attributes: The SoC vendor can declare attributes
> > > > +			  to export some strings to user-space, like the serial-number for
> > > > +			  example.
> > > > +
> > > > +Users:
> > > > +		User-space applications which needs these kind of attributes.
> > 
> > I thought I rejected this the last time it came around?
> > 
> 
> Greg,
> 
> Do you mind sharing the link of the thread where you have reject this?

I don't remember it, you can search as well as I can :)

> > I still fail to understand why this is needed, please provide more
> > information about why you feel this is something that the kernel needs.
> 
> In case of OMAP, there are few ids that we would expose to user space,
> like serial, revision and die id to quote some from top of my mind.
> I must emphasize  that these are not data from CPU at all, they belong
> to SoC itself.

I understand, but note that there could be multiple SoC devices, right?
How will this code support that?

Make this a "real" device not /sys/socinfo please.  It can be a platform
device that export the needed information, that way you can have
multiple ones.

thanks,

greg k-h