Re: [PATCH] ARM: dts: da850-evm: add clock properties to the nand node

[David Lechner]

On 02/06/2018 07:51 AM, Sekhar Nori wrote:
> On Tuesday 06 February 2018 06:38 PM, Bartosz Golaszewski wrote:
> > 2018-02-06 12:07 GMT+01:00 Sekhar Nori <nsekhar@xxxxxx>:
> > > On Monday 05 February 2018 09:22 PM, Bartosz Golaszewski wrote:
> > > > From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> > > >
> > > > Make nand work with the common clock framework by specifying which
> > > > clock should be used and what name to look up.
> > > >
> > > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> > > > ---
> > > >   arch/arm/boot/dts/da850-evm.dts | 3 +++
> > > >   1 file changed, 3 insertions(+)
> > > >
> > > > diff --git a/arch/arm/boot/dts/da850-evm.dts b/arch/arm/boot/dts/da850-evm.dts
> > > > index a86a8a1816f2..2602ad8e99ee 100644
> > > > --- a/arch/arm/boot/dts/da850-evm.dts
> > > > +++ b/arch/arm/boot/dts/da850-evm.dts
> > > > @@ -296,6 +296,9 @@
> > > >                        reg = <0 0x02000000 0x02000000
> > > >                               1 0x00000000 0x00008000>;
> > > >
> > > > +                     clocks = <&psc0 3>;
> > > > +                     clock-names = "aemif";
> > >
> > > Looks like this is being added only to satisfy the devm_clk_get() call
> > > in nand_davinci_probe() which I think is superfluous since we also
> > > enable the same clock in aemif_probe().
> > >
> > > Perhaps the better solution is to drip the clk code in
> > > drivers/mtd/nand/davinci_nand.c and shift legacy code to start using
> > > drivers/memory/aemif.c as well? This way we can also drop
> > > arch/arm/mach-davinci/aemif.c
> > >
> > > Thanks,
> > > Sekhar
> >
> > Yes, this sounds good, but I think we should leave it for later as an
> > additional improvement, once everything else is in place. I think
> > these patches should be applied together with David's series in order
> > to not break the support on davinci boards and the aemif work would go
> > in later as a follow-up. How about that?
>
> No, I dont think we should add temporary hacks to DT to work around
> driver issues (I do think its a hack since the clock belongs to aemif
> module not NAND flash).
>
> An easier driver hack might be to not treat devm_clk_get() failure in
> davinci_nand.c as catastrophic. It will safely fail in DT case and we
> should get the clock in legacy boot case.
>
> I think we are looking at a driver update dependency anyway.

It looks like keystone.dtsi is using the clock-ranges property in the
aemif node to pass the clock to child nodes. Could we not do the same
in da850.dtsi?

> > Also: I don't have any keystone board to test whether such changes
> > don't break the nand support there. Would you be able to test this?
>
> Yes, I have access to those boards.
>
> Thanks,
> Sekhar