On Fri, Feb 11, 2022 at 04:12:29PM +0100, Paul Kocialkowski wrote: > Hi Rob, > > On Fri 11 Feb 22, 09:03, Rob Herring wrote: > > On Sat, Feb 05, 2022 at 07:53:28PM +0100, Paul Kocialkowski wrote: > > > The Allwinner A31 MIPI D-PHY block supports both tx and rx directions, > > > although each instance of the block is meant to be used in one > > > direction only. There will typically be one instance for MIPI DSI and > > > one for MIPI CSI-2 (it seems unlikely to ever see a shared instance). > > > > > > Describe the direction with a new allwinner,direction property. > > > For backwards compatibility, the property is optional and tx mode > > > should be assumed by default. > > > > > > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx> > > > --- > > > .../bindings/phy/allwinner,sun6i-a31-mipi-dphy.yaml | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/phy/allwinner,sun6i-a31-mipi-dphy.yaml b/Documentation/devicetree/bindings/phy/allwinner,sun6i-a31-mipi-dphy.yaml > > > index d0b541a461f3..22636c9fdab8 100644 > > > --- a/Documentation/devicetree/bindings/phy/allwinner,sun6i-a31-mipi-dphy.yaml > > > +++ b/Documentation/devicetree/bindings/phy/allwinner,sun6i-a31-mipi-dphy.yaml > > > @@ -37,6 +37,18 @@ properties: > > > resets: > > > maxItems: 1 > > > > > > + allwinner,direction: > > > + $ref: '/schemas/types.yaml#/definitions/string' > > > + description: | > > > + Direction of the D-PHY: > > > + - "rx" for receiving (e.g. when used with MIPI CSI-2); > > > + - "tx" for transmitting (e.g. when used with MIPI DSI). > > > + > > > + enum: > > > + - tx > > > + - rx > > > + default: tx > > > > Can you the phy mode to imply the direction? > > So there was a first attempt at this which introduced a PHY submode but > it was concluded after discussions that the direction is not really a > mode of operation choice, in the sense that the D-PHY cannot be reconfigured > to behave in Rx or Tx mode: it is instead statically assigned to one role > or the other. This is why it feels more appropriate to describe it in the > device-tree. Another option could be different compatible strings, as the RX and TX PHYs actually have very little in common. I don't mind much either way. > See this thread from the previous iteration: > https://patchwork.linuxtv.org/project/linux-media/patch/20210115200141.1397785-3-paul.kocialkowski@xxxxxxxxxxx/#128800 -- Regards, Laurent Pinchart
