linux-kernel - Re: [char-misc-next 2/3] mei: adding sysfs fw

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Message-ID: <20130801073240.GA5419@kroah.com>
Date:	Thu, 1 Aug 2013 15:32:40 +0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	"Winkler, Tomas" <tomas.winkler@...el.com>
Cc:	"arnd@...db.de" <arnd@...db.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Ovsyanikov, Natalia" <natalia.ovsyanikov@...el.com>
Subject: Re: [char-misc-next 2/3] mei: adding sysfs fw_status attribute

On Thu, Aug 01, 2013 at 07:21:30AM +0000, Winkler, Tomas wrote:
> > 
> > On Mon, Jul 29, 2013 at 11:08:52PM +0000, Winkler, Tomas wrote:
> > > How do I add new device specific sysfs in non-race way if my entry
> > > point is the pci probe function.
> > 
> > You do it in the device creation for the device you add below the PCI device
> > in sysfs, by setting the groups field in the device.
> > 
> > You don't create files in the sysfs directory for the PCI device itself, those are
> > owned by the PCI bus core.
> > 
> > This is why you are your own "bus" here, use it :)
> 
> > If you still have questions, how about we take it to code, post what you have,
> > and I'll see what needs to be changed.
> > 
> > hope this helps,
> 
> Right but this is not related to mei_cl_bus,  which is an abstraction
> in MEI protocol level, I wanted to augment the pci device.

Then do that in the pci core :)

> We'd I've tried to expose is the FW status register from pci config
> space, (I' know the pci config space Is already exposed through syfs),
> the issue is that the  offset of the registers changes between
> different HW, so I wished that there Is a sysfs entry called fw_status
> always points to the correct offset.  An application that tries to
> query fw status can be oblivious to underlying HW SKU. 
> 
> I guess that sysfs is not good interface for that now.  I will just
> resend the two other patches w/o sysfs 

No, you would be adding "random" files to a pci device in sysfs, how
would userspace ever know about something like this?

If this is a PCI-standard thing, then add it to the PCI core please.
Otherwise, it belongs on your "controller" as it is a child of the PCI
device, and should be able to live there just fine.

thanks,

greg k-h
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