Re: 回复: [PATCH v2 1/3] dt-bindings: phy: jh7110-usb-phy: Add sys-syscon property

[Conor Dooley <conor@kernel.org>]

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On Thu, Aug 15, 2024 at 10:33:55AM +0000, Minda Chen wrote:
> 
> 
> > 
> > On Tue, Aug 13, 2024 at 07:31:50AM +0200, Jan Kiszka wrote:
> > > On 12.08.24 17:55, Conor Dooley wrote:
> > > > On Mon, Aug 12, 2024 at 04:15:51PM +0200, Jan Kiszka wrote:
> > > >> From: Jan Kiszka <jan.kiszka@siemens.com>
> > > >>
> > > >> Analogously to the PCI PHY, access to sys_syscon is needed to
> > > >> connect the USB PHY to its controller.
> > > >>
> > > >> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> > > >> Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
> > > >> ---
> > > >> CC: Rob Herring <robh@kernel.org>
> > > >> CC: Krzysztof Kozlowski <krzk+dt@kernel.org>
> > > >> CC: Conor Dooley <conor+dt@kernel.org>
> > > >> ---
> > > >>  .../bindings/phy/starfive,jh7110-usb-phy.yaml         | 11
> > +++++++++++
> > > >>  1 file changed, 11 insertions(+)
> > > >>
> > > >> diff --git
> > > >> a/Documentation/devicetree/bindings/phy/starfive,jh7110-usb-phy.yam
> > > >> l
> > > >> b/Documentation/devicetree/bindings/phy/starfive,jh7110-usb-phy.yam
> > > >> l index 269e9f9f12b6..eaf0050c6f17 100644
> > > >> ---
> > > >> a/Documentation/devicetree/bindings/phy/starfive,jh7110-usb-phy.yam
> > > >> l
> > > >> +++ b/Documentation/devicetree/bindings/phy/starfive,jh7110-usb-phy
> > > >> +++ .yaml
> > > >> @@ -19,6 +19,16 @@ properties:
> > > >>    "#phy-cells":
> > > >>      const: 0
> > > >>
> > > >> +  starfive,sys-syscon:
> > > >> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> > > >> +    items:
> > > >> +      - items:
> > > >> +          - description: phandle to System Register Controller
> > sys_syscon node.
> > > >> +          - description: PHY connect offset of
> > SYS_SYSCONSAIF__SYSCFG register for USB PHY.
> > > >
> > > > Why is having a new property for this required? The devicetree only
> > > > has a single usb phy, so isn't it sufficient to look up the syscon
> > > > by compatible, rather than via phandle + offset?
> > > >
> > >
> > > I didn't design this, I just copied it from
> > > starfive,jh7110-pcie-phy.yaml. As that already exists, I'm neither
> > > sure we want to change that anymore nor deviate in the pattern here.
> > 
> > To be honest, I think some of the other users of phandle + offset on this soc were
> > just copy-pasted without thinking about whether or not they were required too.
> > This one seems like it should just be a lookup by compatible in the driver instead
> > of by phandle. As a bonus, it will work with existing devicetrees - whereas your
> > current implementation will fail to probe on systems that have the old
> > devicetree, a regression for systems running with that devicetree and
> > downstream firmware.
> > 
> > Cheers,
> > Conor.
> > 
> Hi Conor
> I know you would like to put the offset value to the code, Just set syscon in dts.
> Just like pcie-starfive.c. right?

No, not quite. That still uses a phandle lookup, I was talking about
using syscon_regmap_lookup_by_compatible().

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