Hi, On Fri, Sep 28, 2018 at 8:56 PM Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> wrote: > > Hi Chen-Yu, > > On Fri, Sep 28, 2018 at 07:10:58PM +0800, Chen-Yu Tsai wrote: > > On Fri, Sep 28, 2018 at 6:23 PM Sakari Ailus > > <sakari.ailus@xxxxxxxxxxxxxxx> wrote: > > > > > > Hi Laurent, > > > > > > On Fri, Sep 28, 2018 at 12:45:12PM +0300, Laurent Pinchart wrote: > > > > Hi Sakari, > > > > > > > > On Friday, 28 September 2018 12:38:33 EEST Sakari Ailus wrote: > > > > > On Wed, Sep 26, 2018 at 04:40:04PM +0800, Yong Deng wrote: > > > > > > Add binding documentation for Allwinner V3s CSI. > > > > > > > > > > > > Acked-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxx> > > > > > > Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > > > > > > > > > > I know... but I have a few more comments. > > > > > > > > > > > Reviewed-by: Rob Herring <robh@xxxxxxxxxx> > > > > > > Signed-off-by: Yong Deng <yong.deng@xxxxxxxxxxxx> > > > > > > --- > > > > > > > > > > > > .../devicetree/bindings/media/sun6i-csi.txt | 59 +++++++++++++++++ > > > > > > 1 file changed, 59 insertions(+) > > > > > > create mode 100644 Documentation/devicetree/bindings/media/sun6i-csi.txt > > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/media/sun6i-csi.txt > > > > > > b/Documentation/devicetree/bindings/media/sun6i-csi.txt new file mode > > > > > > 100644 > > > > > > index 000000000000..2ff47a9507a6 > > > > > > --- /dev/null > > > > > > +++ b/Documentation/devicetree/bindings/media/sun6i-csi.txt > > > > > > @@ -0,0 +1,59 @@ > > > > > > +Allwinner V3s Camera Sensor Interface > > > > > > +------------------------------------- > > > > > > + > > > > > > +Allwinner V3s SoC features two CSI module. CSI0 is used for MIPI CSI-2 > > > > > > +interface and CSI1 is used for parallel interface. > > > > > > + > > > > > > +Required properties: > > > > > > + - compatible: value must be "allwinner,sun8i-v3s-csi" > > > > > > + - reg: base address and size of the memory-mapped region. > > > > > > + - interrupts: interrupt associated to this IP > > > > > > + - clocks: phandles to the clocks feeding the CSI > > > > > > + * bus: the CSI interface clock > > > > > > + * mod: the CSI module clock > > > > > > + * ram: the CSI DRAM clock > > > > > > + - clock-names: the clock names mentioned above > > > > > > + - resets: phandles to the reset line driving the CSI > > > > > > + > > > > > > +Each CSI node should contain one 'port' child node with one child > > > > > > 'endpoint' +node, according to the bindings defined in > > > > > > +Documentation/devicetree/bindings/media/video-interfaces.txt. As > > > > > > mentioned > > > > > > +above, the endpoint's bus type should be MIPI CSI-2 for CSI0 and parallel > > > > > > or +Bt656 for CSI1. > > > > > > > > > > Which port represents CSI0 and which one is CSI1? That needs to be > > > > > documented. > > > > > > > > There are two CSI devices, named CSI0 and CSI1, with one port each. The CSI0 > > > > device supports CSI-2 only, and the CSI1 device parallel (BT.601 or BT.656) > > > > only. > > > > > > > > > > + > > > > > > +Endpoint node properties for CSI1 > > > > > > > > > > How about CSI0? I'd expect at least data-lanes, and clock-lanes as well if > > > > > the hardware supports lane mapping. > > > > > > > > I enquired about that too. As far as I understand, CSI0 isn't supported yet in > > > > the driver due to lack of documentation and lack of open-source vendor- > > > > provided source code. While DT bindings are not tied to driver > > > > implementations, it's not the best idea to design DT bindings without at least > > > > one working implementation to test them. I thus proposed just listing CSI0 as > > > > being unsupported for now. > > > > > > Ack. > > > > > > We should still define which receiver corresponds to a given port. Probably > > > 1 for CSI1 would make sense, in order to avoid changing the order the > > > hardware already uses. 0 doesn't need to be documented no IMO. > > > > > > What do you think? > > > > AFAICT it would be a completely seperate node, since they have different address > > spaces, clocks and reset controls. So there's no possibility of confusion. > > > > According to Yong, CSI0 is tied internally to some unknown MIPI CSI2-receiver, > > which is the undocumented part. CSI1 has its parallel data pins exposed to the > > outside. > > Thanks for clearing up the confusion. If these are truly different kinds of > devices, then don't they also deserve different compatible strings? And > possibly also different DT binding documentation in a separate file. Allwinner's documents aren't particularly clear about this. AFAICT it does not say anything about them being different. The CSI section gives a register table with two base addresses. The V3S SDK listed on linux-sunxi wiki also doesn't differentiate between the two. What's more is there's actually code and register addresses for the MIPI stuff [1], though the license is questionable, as with most BSPs. It indeed seems like a CSI controller, which basically just takes whatever input it is configured for and sends it to either a downstream ISP or DRAM. There are MIPI-CSI receiver and DPHY blocks in addresses following CSI0, but we can treat them as separate hardware blocks. ChenYu [1] https://github.com/yeashen/v3s-linux-sdk/blob/master/linux-3.4/drivers/media/video/sunxi-vfe/platform/sun8iw8p1_vfe_cfg.h#L27
