Re: [PATCH] add new NRP power meter USB device driver

[Oliver Neukum]

Am Donnerstag, 31. Mai 2012, 14:48:45 schrieb Greg KH:
> On Thu, May 31, 2012 at 02:32:40PM +0200, Oliver Neukum wrote:
> >  Am Donnerstag, 31. Mai 2012, 14:04:11 schrieben Sie:
> > > On Thu, May 31, 2012 at 12:17:11PM +0200, Oliver Neukum wrote:
> > > > Am Donnerstag, 31. Mai 2012, 11:53:04 schrieb Greg KH:
> > > > > > So it is a chicken and egg problem. A lot of software is now out with
> > > > > > depends on this driver and a lot of embedded development environments
> > > > > > doesn't provide libudev, libsysfs und libusb. It will also increase the
> > > > > > size of the image and adds additional dependencies to the application.
> > > > > 
> > > > > You don't need any of those libraries to do this.  What's wrong with
> > > > > using "raw" usbfs interactions?
> > > > 
> > > > SPI is not limited to USB. If we can get a unified subsystem then the
> > > > drivers need to be in kernel space, as some hardware does not allow
> > > > a solution in user space.
> > > 
> > > Ok, now that is a valid reason for a kernel driver.
> > > 
> > > But, I think it should use the IIO interface, as that should handle
> > > these types of devices.
> > 
> > Bad gamble for the future. We will end up with an interface which
> > would not be implementable.
> 
> Why do you say that?  What's wrong with IIO?

It seems to specialised for this kind of IO. SPI over USB is closer to a generic
thing rather like sg or even a bus rather than an IIO device. Kernel space drivers
that use SPI might belong into IIO. The infrastructure itself not so much.

	Regards
		Oliver
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