Hi Christophe, Boris,
On Tue, May 02, 2017 at 11:03:34AM +0200, Boris Brezillon wrote:
> On Tue, 2 May 2017 07:47:40 +0200
> Christophe LEROY <christophe.le...@c-s.fr> wrote:
>
> > Le 01/05/2017 à 23:46, Brian Norris a écrit :
> > > On Fri, Feb 10, 2017 at 03:01:10PM +0100, Christophe Leroy wrote:
> > >> On some hardware, the nCE signal is wired to the ChipSelect associated
> > >> to bus address of the NAND, so it is automatically driven during the
> > >> memory access and it is not managed by a GPIO.
> > >>
> > >> Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
> > >
> > > Not really a problem with this patch exactly, but FYI you're only making
> > > this optional for the non-DT case. For device tree, this is kinda hard
> > > to do, since the current binding suggests we retrieve the GPIOs based on
> > > index position, not by name. So if you leave one off...I guess we well
> > > just be off-by-1 on the indeces until we hit a non-optional one...which
> > > I guess is "CLE".
> > >
> > > If we wanted this to work for DT, we'd need to extend this driver (and
> > > binding doc) to support requesting GPIOs by name.
> > >
> >
> > It works for me with devicetree.
> >
> > I have the following definition in my DT:
> >
> > nand@1,0 {
> > compatible = "gpio-control-nand";
> > reg = <1 0x0 0x01>;
> > #address-cells = <1>;
> > #size-cells = <1>;
> > gpios = <&qe_pio_c 24 1 // RDY
> > 0 // nCE
> > &qe_pio_c 26 1 // ALE
> > &qe_pio_c 25 1 // CLE
> > 0>; // nwp
> > };
> >
>
> Yep, it's perfectly fine to have 'empty' gpio entries (entries with
> phandle set to 0/NULL), we're using this trick in the atmel_nand
> driver as well.
I wasn't aware. In that case, you need to change the binding doc to
note that nCE is optional now.
Brian
