Re: [PATCH v3 6/6] dt-bindings: fpga: Add bindings for ZynqMP fpga driver

[Rob Herring]

On Mon, Mar 4, 2019 at 5:35 AM Nava kishore Manne <navam@xxxxxxxxxx> wrote:
>
> Hi Rob,
>
>  Thanks for providing the review comments..
> Please find my response inline.
>
> > -----Original Message-----
> > From: Rob Herring [mailto:robh@xxxxxxxxxx]
> > Sent: Saturday, February 23, 2019 2:01 AM
> > To: Nava kishore Manne <navam@xxxxxxxxxx>
> > Cc: mark.rutland@xxxxxxx; Michal Simek <michals@xxxxxxxxxx>; Rajan Vaja
> > <RAJANV@xxxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; Jolly Shah
> > <JOLLYS@xxxxxxxxxx>; chinnikishore369@xxxxxxxxx
> > Subject: Re: [PATCH v3 6/6] dt-bindings: fpga: Add bindings for ZynqMP fpga
> > driver
> >
> > On Wed, Jan 23, 2019 at 2:46 PM Nava kishore Manne <navam@xxxxxxxxxx>
> > wrote:
> > >
> > > Hi Rob,
> > >
> > >
> > >
> > > Thanks for providing the comments...
> >
> > Please fix your mailer to send plain text emails to mail lists.
> >
> Thanks for pointing it..
>
> >
> > > > -----Original Message-----
> > >
> > > > From: Rob Herring [mailto:robh@xxxxxxxxxx]
> > >
> > > > Sent: Monday, January 21, 2019 9:19 PM
> > >
> > > > To: Nava kishore Manne <navam@xxxxxxxxxx>
> > >
> > > > Cc: mark.rutland@xxxxxxx; Michal Simek <michals@xxxxxxxxxx>; Rajan
> > > > Vaja
> > >
> > > > <RAJANV@xxxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-
> > >
> > > > kernel@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; Jolly Shah
> > >
> > > > <JOLLYS@xxxxxxxxxx>; chinnikishore369@xxxxxxxxx
> > >
> > > > Subject: Re: [PATCH v3 6/6] dt-bindings: fpga: Add bindings for
> > > > ZynqMP fpga
> > >
> > > > driver
> > >
> > > >
> > >
> > > > On Mon, Jan 21, 2019 at 11:08:35PM +0530, Nava kishore Manne wrote:
> > >
> > > > > Add documentation to describe Xilinx ZynqMP fpga driver bindings.
> > >
> > > > >
> > >
> > > > > Signed-off-by: Nava kishore Manne <nava.manne@xxxxxxxxxx>
> > >
> > > > > ---
> > >
> > > > > Changes for v3:
> > >
> > > > >                         -Removed PCAP as a child node to the FW
> > > > > and Created
> > >
> > > > >                         an independent node since PCAP driver is a
> > > > > consumer
> > >
> > > > >                         not a provider.
> > >
> > > > >
> > >
> > > > >  .../bindings/fpga/xlnx,zynqmp-pcap-fpga.txt         | 13 +++++++++++++
> > >
> > > > >  1 file changed, 13 insertions(+)
> > >
> > > > >  create mode 100644
> > >
> > > > > Documentation/devicetree/bindings/fpga/xlnx,zynqmp-pcap-fpga.txt
> > >
> > > > >
> > >
> > > > > diff --git
> > >
> > > > > a/Documentation/devicetree/bindings/fpga/xlnx,zynqmp-pcap-fpga.txt
> > >
> > > > > b/Documentation/devicetree/bindings/fpga/xlnx,zynqmp-pcap-fpga.txt
> > >
> > > > > new file mode 100644
> > >
> > > > > index 000000000000..1f6f58872311
> > >
> > > > > --- /dev/null
> > >
> > > > > +++ b/Documentation/devicetree/bindings/fpga/xlnx,zynqmp-pcap-fpga
> > > > > +++ .txt
> > >
> > > > > @@ -0,0 +1,13 @@
> > >
> > > > > +Device Tree zynqmp-fpga bindings for the Zynq Ultrascale+ MPSoC
> > >
> > > > > +controlled using ZynqMP SoC firmware interface For Bitstream
> > >
> > > > > +configuration on ZynqMp Soc uses processor configuration
> > >
> > > > > +port(PCAP) to configure the programmable logic(PL) through PS by
> > >
> > > > > +using FW interface.
> > >
> > > > > +
> > >
> > > > > +Required properties:
> > >
> > > > > +- compatible: should contain "xlnx,zynqmp-pcap-fpga"
> > >
> > > > > +
> > >
> > > > > +Example:
> > >
> > > > > +      zynqmp_pcap: pcap {
> > >
> > > > > +                     compatible = "xlnx,zynqmp-pcap-fpga";
> > >
> > > > > +      };
> > >
> > > >
> > >
> > > > There's no need for a DT node. Just make the firware driver create a
> > > > platform
> > >
> > > > device for pcap.
> > >
> > > >
> > >
> > >
> > >
> > > This driver being used by the FPGA manager framework(fpga-region) to apply
> > overlay's so this node is needed AFAIK.
> >
> > The binding says nothing about child nodes and what they are. Please define
> > that.
> >
> Do you mean I need to add the example usage of the pcap node like as below in the binding doc?

You can have an example, but no, I meant you need say something like
"The pcap node may have 1 or more child nodes which have an
'fpga-region' compatible.
>
> Device Tree Example for Full Reconfiguration
> ============================================
>
> Live Device Tree contains:
>
>         zynqmp_pcap: pcap {
>                 compatible = "xlnx,zynqmp-pcap-fpga";
>         };
>
>         fpga_region0: fpga-region0 {

This should be a child of pcap.

>                 compatible = "fpga-region";
>                 fpga-mgr = <&zynqmp_pcap>;
>                 #address-cells = <0x1>;
>                 #size-cells = <0x1>;
>                 ranges;
>         };
>
> DT Overlay contains:

Don't show overlays in examples. Just show a final tree (i.e. base
with overlay applied).

> /dts-v1/ /plugin/;
> / {
> fragment@0 {
>         target = <&fpga_region0>;
>         #address-cells = <1>;
>         #size-cells = <1>;
>         __overlay__ {
>                 #address-cells = <1>;
>                 #size-cells = <1>;
>
>                 firmware-name = "zynqmp-gpio.bin";
>
>                 gpio1: gpio@40000000 {
>                         compatible = "xlnx,xps-gpio-1.00.a";
>                         reg = <0x40000000 0x10000>;
>                         gpio-controller;
>                         #gpio-cells = <0x2>;
>                         xlnx,gpio-width= <0x6>;
>                 };
>         };
> };
>
> Please correct me if my understanding is wrong.
>
> Regards,
> Navakishore.