Re: [LINUX PATCH v9 1/4] Devicetree: Add pl353 smc controller devicetree binding information

From: Miquel Raynal
Date: Thu Jun 07 2018 - 11:47:36 EST


Hi Miquel,

On Thu, 7 Jun 2018 17:42:03 +0200, Miquel Raynal
<miquel.raynal@xxxxxxxxxxx> wrote:

> Hi Naga,
>
> On Wed, 6 Jun 2018 13:19:39 +0530, Naga Sureshkumar Relli
> <naga.sureshkumar.relli@xxxxxxxxxx> wrote:
>
> > Add pl353 static memory controller devicetree binding information.
> >
> > Signed-off-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xxxxxxxxxx>
> > ---
> > Changes in v9:
> > - Addressed commens given by Randy Dunlap and Miquel Raynal
>
> Can you please be more specific in your next changelog? I don't
> remember what I suggested a few months ago :)
>
> > Changes in v8:
> > - None
> > Changes in v7:
> > - Corrected clocks description
> > - prefixed '#' for address and size cells
> > Changes in v6:
> > - None
> > Changes in v5:
> > - Removed timing properties
> > Changes in v4:
> > - none
> > Changes in v3:
> > - none
> > Changes in v2:
> > - modified timing binding info as per onfi timing parameters
> > - add suffix nano second as timing unit
> > - modified the clock names as per the IP spec
> > ---
> > .../bindings/memory-controllers/pl353-smc.txt | 53 ++++++++++++++++++++++
> > 1 file changed, 53 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt
> >
> > diff --git a/Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt b/Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt
> > new file mode 100644
> > index 0000000..551e66b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt
> > @@ -0,0 +1,53 @@
> > +Device tree bindings for ARM PL353 static memory controller
> > +
> > +PL353 static memory controller supports two kinds of memory
> > +interfaces.i.e NAND and SRAM/NOR interfaces.
> > +The actual devices are instantiated from the child nodes of pl353 smc node.
> > +
> > +Required properties:
> > +- compatible : Should be "arm,pl353-smc-r2p1"
>
> I thing Rob prefers:
>
> - compatible: Must be one of:
> * arm, pl353-smc-r2p1
>
> > +- reg : Controller registers map and length.
> > +- clock-names : List of input clock names - "ref_clk", "aper_clk"
> > + (See clock bindings for details).
> > +- clocks : Clock phandles (see clock bindings for details).
> > +- address-cells : Address cells, must be 1.
> > +- size-cells : Size cells. Must be 1.
>
> Please avoid padding, just this is enough:
>
> - something: And another thing.
>
> > +
> > +Child nodes:
> > + For NAND the "arm,pl353-nand-r2p1" and for NOR the "cfi-flash" drivers are
> > +supported as child nodes.
> > +
> > +Mandatory timing properties for child nodes:
> > +- arm,nand-cycle-t0 : Read cycle time(t_rc).
> > +- arm,nand-cycle-t1 : Write cycle time(t_wc).
> > +- arm,nand-cycle-t2 : re_n assertion delay(t_rea).
> > +- arm,nand-cycle-t3 : we_n de-assertion delay(t_wp).
> > +- arm,nand-cycle-t4 : Status read time(t_clr)
> > +- arm,nand-cycle-t5 : ID read time(t_ar)
> > +- arm,nand-cycle-t6 : busy to re_n(t_rr)
>
> I think this has nothing to do in the DT, you should handle timings
> from the ->setup_data_interface() hook. If you need, you may use
> different compatibles to distinguish different platform data.

Actually these are NAND-chip dependant and should be derived from the
timings given by the core in the SDR interface structure by
->setup_data_interface().