Re: [PATCH v5 2/8] dt-bindings: phy: rockchip,rk3588-mipi-dcphy: Add a cell to select TX or RX

[Rob Herring <robh@kernel.org>]

On Fri, Oct 16, 2026 at 04:56:36PM +0800, Jason Yang wrote:
> The Samsung MIPI D-/C-PHY block on RK3588 and RK3576 has a transmitter
> for DSI and a receiver for CSI-2, and two consumers can use them at the
> same time. The single cell of this binding selects the mode and refers
> to the transmitter, so the receiver cannot be described.
> 
> Allow a second cell that selects the transmitter or the receiver. With
> D-PHY:
> 
> 	/* the MIPI DSI host, driving the transmitter */
> 	phys = <&mipidcphy0 PHY_TYPE_DPHY PHY_DIRECTION_TX>;
> 
> 	/* the MIPI CSI-2 host, driving the receiver */
> 	phys = <&mipidcphy0 PHY_TYPE_DPHY PHY_DIRECTION_RX>;
> 
> and with C-PHY:
> 
> 	phys = <&mipidcphy0 PHY_TYPE_CPHY PHY_DIRECTION_TX>;
> 	phys = <&mipidcphy0 PHY_TYPE_CPHY PHY_DIRECTION_RX>;
> 
> The transmitter and the receiver cannot operate in different modes [1],
> so the first cell must match in both consumers.
> 
> Two cells describe the receiver as well. A single cell keeps referring
> to the transmitter, so existing device trees are unaffected.
> 
> [1] RK3588 TRM: section 22.1 (overview): "The TX and RX only support
>     operate in the same PHY mode."

The problem here is this is an ABI break. An existing OS will not know 
what to do with 2 cells. Perhaps adding flags to the upper bits of the 
existing cell would work.

Rob