RE: [PATCH net-next 2/2] net: macb: Add zynqmp SGMII dynamic configuration support

[Pandey, Radhey Shyam]

> -----Original Message-----
> From: Pandey, Radhey Shyam <radhey.shyam.pandey@xxxxxxx>
> Sent: Wednesday, July 27, 2022 12:18 AM
> To: Andrew Lunn <andrew@xxxxxxx>
> Cc: michal.simek@xxxxxxxxxx; nicolas.ferre@xxxxxxxxxxxxx;
> claudiu.beznea@xxxxxxxxxxxxx; davem@xxxxxxxxxxxxx;
> edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx;
> gregkh@xxxxxxxxxxxxxxxxxxx; ronak.jain@xxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx; git@xxxxxxxxxx; git (AMD-Xilinx) <git@xxxxxxx>
> Subject: RE: [PATCH net-next 2/2] net: macb: Add zynqmp SGMII dynamic
> configuration support
> 
> 
> 
> > -----Original Message-----
> > From: Andrew Lunn <andrew@xxxxxxx>
> > Sent: Monday, July 25, 2022 10:41 PM
> > To: Pandey, Radhey Shyam <radhey.shyam.pandey@xxxxxxx>
> > Cc: michal.simek@xxxxxxxxxx; nicolas.ferre@xxxxxxxxxxxxx;
> > claudiu.beznea@xxxxxxxxxxxxx; davem@xxxxxxxxxxxxx;
> > edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx;
> > gregkh@xxxxxxxxxxxxxxxxxxx; ronak.jain@xxxxxxxxxx; linux-arm-
> > kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > netdev@xxxxxxxxxxxxxxx; git@xxxxxxxxxx; git (AMD-Xilinx) <git@xxxxxxx>
> > Subject: Re: [PATCH net-next 2/2] net: macb: Add zynqmp SGMII dynamic
> > configuration support
> >
> > On Mon, Jul 25, 2022 at 02:34:51PM +0000, Pandey, Radhey Shyam wrote:
> > > > -----Original Message-----
> > > > From: Andrew Lunn <andrew@xxxxxxx>
> > > > Sent: Sunday, July 24, 2022 10:24 PM
> > > > To: Pandey, Radhey Shyam <radhey.shyam.pandey@xxxxxxx>
> > > > Cc: michal.simek@xxxxxxxxxx; nicolas.ferre@xxxxxxxxxxxxx;
> > > > claudiu.beznea@xxxxxxxxxxxxx; davem@xxxxxxxxxxxxx;
> > > > edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx;
> > > > gregkh@xxxxxxxxxxxxxxxxxxx; ronak.jain@xxxxxxxxxx; linux-arm-
> > > > kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > > > netdev@xxxxxxxxxxxxxxx; git@xxxxxxxxxx; git (AMD-Xilinx)
> > > > <git@xxxxxxx>
> > > > Subject: Re: [PATCH net-next 2/2] net: macb: Add zynqmp SGMII
> > > > dynamic configuration support
> > > >
> > > > > +		ret = of_property_read_u32_array(pdev-
> >dev.of_node,
> > > > "power-domains",
> > > > > +						 pm_info,
> > > > ARRAY_SIZE(pm_info));
> > > > > +		if (ret < 0) {
> > > > > +			dev_err(&pdev->dev, "Failed to read power
> > > > management information\n");
> > > > > +			return ret;
> > > > > +		}
> > > > > +		ret = zynqmp_pm_set_gem_config(pm_info[1],
> > > > GEM_CONFIG_FIXED, 0);
> > > > > +		if (ret < 0)
> > > > > +			return ret;
> > > > > +
> > > >
> > > > Documentation/devicetree/bindings/net/cdns,macb.yaml says:
> > > >
> > > >   power-domains:
> > > >     maxItems: 1
> > > >
> > > > Yet you are using pm_info[1]?
> > >
> > > >From power-domain description - It's a phandle and PM domain
> > > specifier as defined by bindings of the power controller specified
> > > by phandle.
> > >
> > > I assume the numbers of cells is specified by "#power-domain-cells":
> > > Power-domain-cell is set to 1 in this case.
> > >
> > > arch/arm64/boot/dts/xilinx/zynqmp.dtsi
> > > #power-domain-cells = <1>;
> > > power-domains = <&zynqmp_firmware PD_ETH_0>;
> > >
> > > Please let me know your thoughts.
> >
> > Ah, so you ignore the phandle value, and just use the PD_ETH_0?
> >
> > How robust is this? What if somebody specified a different power domain?
> 
> Some background - init_reset_optional() fn is implemented for three
> platforms i.e., zynqmp, versal, MPFS.
> 
> zynqmp_pm_set_gem_config API expect first argument as GEM node id so,
> power-domain DT property is passed to get node ID.
> 
> However, power-domain property is read only if underlying firmware
> supports configuration of GEM secure space. It's only true for zynqmp SGMII
> case and for zynqmp power domain is fixed.
> In addition to it there is an error handling in power-domain property parsing.
> Hope this answers the question.

Please let me know the implementation looks fine or needs any modification?