Re: [PATCH 2/3] dt-bindings: phy: rockchip-inno-csi-dphy: add rockchip,clk-lane-phase property

[Conor Dooley <conor@kernel.org>]

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On Wed, Jun 17, 2026 at 06:20:19PM +0200, Gerald Loacker wrote:
> Hi Conor,
> 
> Am 17.06.2026 um 17:51 schrieb Conor Dooley:
> > On Wed, Jun 17, 2026 at 02:23:14PM +0200, Gerald Loacker wrote:
> >> Add support for the optional rockchip,clk-lane-phase device tree property
> >> to allow board-specific tuning of the clock lane sampling phase for
> >> improved signal integrity across supported data rates.
> >>
> >> Signed-off-by: Gerald Loacker <gerald.loacker@wolfvision.net>
> >> ---
> >>  Documentation/devicetree/bindings/phy/rockchip-inno-csi-dphy.yaml | 7 +++++++
> >>  1 file changed, 7 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/phy/rockchip-inno-csi-dphy.yaml b/Documentation/devicetree/bindings/phy/rockchip-inno-csi-dphy.yaml
> >> index 03950b3cad08c..0d824d1511bc0 100644
> >> --- a/Documentation/devicetree/bindings/phy/rockchip-inno-csi-dphy.yaml
> >> +++ b/Documentation/devicetree/bindings/phy/rockchip-inno-csi-dphy.yaml
> >> @@ -56,6 +56,13 @@ properties:
> >>      description:
> >>        Some additional phy settings are access through GRF regs.
> >>  
> >> +  rockchip,clk-lane-phase:
> >> +    $ref: /schemas/types.yaml#/definitions/uint32
> >> +    minimum: 0
> >> +    maximum: 7
> >> +    description:
> >> +      Clock lane sampling phase in 40 ps steps. The hardware default is 3.
> > 
> > Can this instead become rockchip,clk-lane-phase-ps and be listed in the
> > actual unit?
> > With the -ps suffix, you can then drop the $ref.
> > The default should be listed as "default: 3" (or default: 120)
> > 
> > pw-bot: changes-requested
> > 
> 
> Thanks for the suggestion.
> 
> The phase setting is a hardware tap index (0–7) selecting a delay line
> position. The datasheet mentions “about 40 ps” per step, but this is not
> a calibrated or guaranteed value and may vary with PVT.
> 
> Because of that, I’d prefer to keep the property as an index and
> document the approximate delay in the description:
> 
> Clock lane sampling phase selection (hardware tap index 0–7). Each step
> corresponds to an approximately 40 ps delay as described in the hardware
> specification.
> 
> This matches the hardware model more closely. Happy to adjust if needed.
> 

Sure, I think that's fair.

> >> +
> >>  required:
> >>    - compatible
> >>    - reg
> >>
> >> -- 
> >> 2.34.1
> >>
> 

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