Subject: Re: [PATCH 1/2] request_firmware without a device
From: Shaohua Li <shaohua.li@intel.com>
To: Greg KH <greg@kroah.com>
Cc: Marcel Holtmann <marcel@holtmann.org>, lkml <linux-kernel@vger.kernel.org>,
       Patrick Mochel <mochel@digitalimplant.org>,
       Andrew Morton <akpm@osdl.org>
In-Reply-To: <20060526040613.GA5324@kroah.com>
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	 <20060526040613.GA5324@kroah.com>
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Date: Fri, 26 May 2006 12:41:22 +0800
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On Thu, 2006-05-25 at 21:06 -0700, Greg KH wrote:
> On Fri, May 26, 2006 at 11:40:39AM +0800, Shaohua Li wrote:
> > On Thu, 2006-05-25 at 12:24 +0200, Marcel Holtmann wrote:
> > > Hi Greg,
> > > 
> > > > > The patch allows calling request_firmware without a 'struct device'.
> > > > > It appears we just need a name here from 'struct device'. I changed it
> > > > > to use a kobject as Patrick suggested.
> > > > > Next patch will use the new API to request firmware (microcode) for a CPU.
> > > > 
> > > > But a cpu does have a struct device.  Why not just use that?
> > > > 
> > > > > +fw_setup_class_device_id(struct class_device *class_dev, struct kobject *kobj)
> > > > >  {
> > > > >  	/* XXX warning we should watch out for name collisions */
> > > > > -	strlcpy(class_dev->class_id, dev->bus_id, BUS_ID_SIZE);
> > > > > +	strlcpy(class_dev->class_id, kobj->k_name, BUS_ID_SIZE);
> > > > 
> > > > There's a function for this, kobject_name(), please never touch k_name
> > > > directly.
> > > > 
> > > > > +EXPORT_SYMBOL(request_firmware_kobj);
> > > > 
> > > > Ick, if you really want to do this, just fix up all callers of
> > > > request_firmware(), there aren't that many of them.
> > > > 
> > > > But I don't recommend it anyway.
> > > 
> > > I also disagree with this change at all. The callers of request_firmware
> > > should not fiddle around with kobject's to make this work. All of them
> > > have their struct device and they should use it.
> > So why we need a 'struct device'? I didn't see any point we need it. We
> > just need a 'name'.
> 
> You need a kobject, as ideally we would have a symlink back to the
> "real" kobject.  So far, only "devices" need firmware, that's why it is
> that way.
> > > So I would propose that we fix the caller and the not request_firmware
> > > code. However one option would be calling it with NULL as device
> > > argument and it registers itself a dummy device for the operation.
> > This doesn't work, as we need a 'name'.
> > 
> > do we really need to differentiate between sysdev and device anymore. I
> > > recall a plan to unify all devices, but I might be wrong.
> > I'd like this idea. But it means many works. In addition, a sysdev could
> > have multiple drivers, and a 'device' can't to me.
> 
> Today a sysdev can have that?  Ick.  Any examples of ones that really
> do?
At least cpu sysdev has two drivers currently. one is mtrr driver the
other is cpurfreq.

Thanks,
Shaohua
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