Re: [PATCH 4/4] dts: s32g: Add GPR syscon region

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Mon, Dec 01, 2025 at 11:42:00AM -0500, Frank Li wrote:
> On Mon, Dec 01, 2025 at 04:08:33PM +0300, Dan Carpenter wrote:
> > Add the GPR syscon region for the s32 chipset.
> >
> > Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> > ---
> >  arch/arm64/boot/dts/freescale/s32g2.dtsi | 8 ++++++++
> >  arch/arm64/boot/dts/freescale/s32g3.dtsi | 8 ++++++++
> >  2 files changed, 16 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/freescale/s32g2.dtsi b/arch/arm64/boot/dts/freescale/s32g2.dtsi
> > index 51d00dac12de..3c9472f6c174 100644
> > --- a/arch/arm64/boot/dts/freescale/s32g2.dtsi
> > +++ b/arch/arm64/boot/dts/freescale/s32g2.dtsi
> > @@ -325,6 +325,13 @@ usdhc0-200mhz-grp4 {
> >  			};
> >  		};
> >
> > +		gpr: syscon@4007c000 {
> > +			compatible = "nxp,s32-gpr", "syscon";
> > +			reg = <0x4007c000 0x3000>;
> > +			#address-cells = <1>;
> > +			#size-cells = <1>;
> > +		};
> > +
> 
> Please cc whole thread to imx@lists.linux.dev.
> 
> I think it is not good method by using syscon here.
> 
> Suppose using standard phy interface or mux controller interface.

I rather disagree, but I would like to see the definition of the
"ctrl_sts" register. The driver defines:

/* SoC PHY interface control register */
#define S32_PHY_INTF_SEL_MII    0x00
#define S32_PHY_INTF_SEL_SGMII  0x01
#define S32_PHY_INTF_SEL_RGMII  0x02
#define S32_PHY_INTF_SEL_RMII   0x08

This is mostly equivalent to the phy_intf_sel_i[2:0] input to the GMAC
block, who's bit combinations are defined by the PHY_INTF_SEL_xxx
constants. These seem to correspond to register bits 3:1, but with
the GMAC being configured for MII mode with an external SGMII PCS
when bit 0 is set.

If this is true, then no, there is no "phy" as such, and if we go
down the route of modelling the GMAC's phy_intf_sel_i[2:0] inputs
as a "phy" then we're going to end up with something that's a
drivers/phy PHY before a real seperate PHY for providing the
SGMII/1000BASE-X signalling. This falls into the category of needless
over-complication with no benefit.

-- 
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