Re: [PATCH v5 1/3] mtd: nand: gpio: Add DT property to automatically determine bus width

[Ezequiel Garcia <ezequiel.garcia@free-electrons.com>]

On Fri, Nov 29, 2013 at 04:35:04PM +0400, Alexander Shiyan wrote:
> > Hi Brian,
> > 
> > On Tue, Nov 26, 2013 at 05:23:38PM -0800, Brian Norris wrote:
> > [..]
> > > > 
> > > > If we do resort to a new binding for auto-buswidth, it should be a
> > > > generic one that all NAND drivers can use.
> > 
> > Why do we need yet another binding to describe something that's
> > completely discoverable?
> > 
> > I'm working on *removing* any need to set the bus width, either from the
> > driver or from the DT, so I see this patch as step backwards.
> > 
> > Can anyone help me understand if there's *any* valid use case where we
> > want to specify a-priori the bus width, considering it's completely
> > discoverable at run-time?
> 
> Look at my previous attempt:
> http://permalink.gmane.org/gmane.linux.drivers.mtd/47411
> http://permalink.gmane.org/gmane.linux.drivers.mtd/47413
> 

I think we're mixing (again) the NAND device bus width with the controller bus
width. The former is discoverable and doesn't belong at DT (or anywhere), the
latter goes beyond NAND (as memory controller's can handle other kinds of flashes)
and is usually required to be specifiedat the DT.

Hence, I think only the latter needs a DT binding.
-- 
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com