Hi Sylwester,
On Tuesday 11 March 2014 14:38:37 Sylwester Nawrocki wrote:
> Hi Laurent,
>
> Thanks for your review.
You're welcome.
> On 11/03/14 13:30, Laurent Pinchart wrote:
> [...]
>
> >> ---
> >>
> >> .../devicetree/bindings/media/samsung-fimc.txt | 34 +++++++++-----
> >> 1 file changed, 26 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/media/samsung-fimc.txt
> >> b/Documentation/devicetree/bindings/media/samsung-fimc.txt index
> >> 96312f6..dbd4020 100644
> >> --- a/Documentation/devicetree/bindings/media/samsung-fimc.txt
> >> +++ b/Documentation/devicetree/bindings/media/samsung-fimc.txt
> >> @@ -32,6 +32,21 @@ way around.
> >>
> >> The 'camera' node must include at least one 'fimc' child node.
> >>
> >> +Optional properties:
> >> +
> >> +- #clock-cells: from the common clock bindings
> >> (../clock/clock-bindings.txt),
> >> + must be 1. A clock provider is associated with the 'camera' node and
> >> it should
> >> + be referenced by external sensors that use clocks provided by the SoC
> >> on
> >> + CAM_*_CLKOUT pins. The clock specifier cell stores an index of a
> >> clock.
> >> + The indices are 0, 1 for CAM_A_CLKOUT, CAM_B_CLKOUT clocks
> >> respectively.
> >> +
> >> +- clock-output-names: from the common clock bindings, should contain
> >> names of
> >> + clocks registered by the camera subsystem corresponding to
> >> CAM_A_CLKOUT,
> >> + CAM_B_CLKOUT output clocks respectively.
> >
> > Wouldn't it be better to document the "cam_mclk_a" and "cam_mclk_b" names
> > explicitly ? Or do you expect different names to be used in different DT
> > files ? And as they correspond to the CAM_A_CLKOUT and CAM_B_CLKOUT pins,
> > shouldn't they be named "cam_a_clkout" and "cam_b_clkout" ?
>
> Basically I could use fixed names for these clocks, I just wanted to keep
> a possibility to override them in dts to avoid any possible clock name
> collisions, rather than keep a list of different names per SoC in the
> driver. Right now fixed names could also be used for all SoCs I'm aware of,
> nevertheless I would prefer to keep the clock-output-names property.
> "cam_a_clkout", "cam_b_clkout" may be indeed better names, I'll change
> that.
OK, variable names are fine with me.
> >> +Note: #clock-cells and clock-output-names are mandatory properties if
> >> external
> >> +image sensor devices reference 'camera' device node as a clock provider.
> >> +
> >
> > What's the reason not to make them always mandatory ? Backward
> > compatibility only ? If so wouldn't it make sense to document the
> > properties as mandatory from now on, and treating them as optional in the
> > driver for backward compatibility ?
>
> Yes, it's for backwards compatibility only. It may be a good idea to just
> document them as required, since this is how the device is expected to be
> described in DT from now. I'll just make these a required properties,
> the driver already handles them as optional.
OK.
> >> 'fimc' device nodes
> >> -------------------
> >>
> >> @@ -97,8 +112,8 @@ Image sensor nodes
> >>
> >> The sensor device nodes should be added to their control bus controller
> >>
> >> (e.g. I2C0) nodes and linked to a port node in the csis or the
> >> parallel-ports node, using the common video interfaces bindings, defined
> >> in video-interfaces.txt.
> >> -The implementation of this bindings requires clock-frequency property to
> >> be
> >> -present in the sensor device nodes.
> >> +An optional clock-frequency property needs to be present in the sensor
> >> device
> >> +nodes. Default value when this property is not present is 24 MHz.
> >
> > This bothers me. Having the FIMC driver read the clock-frequence property
> > from the sensor DT nodes feels like a layering violation. Shouldn't the
> > sensor drivers call clk_set_rate() explicitly instead ?
>
> It is supposed to do so, after this whole patch series. So the camera
> controller driver will not need such properties. What do you think about
> removing this sentence altogether ?
Sure. As the FIMC won't access the clock-frequency property of the sensor
anymore after this patch series, let's just drop the mention of clock-
frequency.
> >> Example:
> >> @@ -114,7 +129,7 @@ Example:
> >> vddio-supply = <...>;
> >>
> >> clock-frequency = <24000000>;
> >>
> >> - clocks = <...>;
> >> + clocks = <&camera 1>;
> >>
> >> clock-names = "mclk";
> >>
> >> port {
> >>
> >> @@ -135,7 +150,7 @@ Example:
> >> vddio-supply = <...>;
> >>
> >> clock-frequency = <24000000>;
> >>
> >> - clocks = <...>;
> >> + clocks = <&camera 0>;
> >>
> >> clock-names = "mclk";
> >>
> >> port {
> >>
> >> @@ -149,12 +164,15 @@ Example:
> >> camera {
> >>
> >> compatible = "samsung,fimc", "simple-bus";
> >>
> >> - #address-cells = <1>;
> >> - #size-cells = <1>;
> >> - status = "okay";
> >> -
> >> + clocks = <&clock 132>, <&clock 133>;
> >> + clock-names = "sclk_cam0", "sclk_cam1";
> >
> > The documentation mentions that clock-names must contain "sclk_cam0",
> > "sclk_cam1", "pxl_async0", "pxl_async1". Are the last two optional ? If so
> > I think you should clarify the description of the clock-names property.
> > This can be done in a separate patch.
>
> "pxl_async0", "pxl_async1" are mandatory, I'll add them also into
> this example dts.
OK.
> >> + #clock-cells = <1>;
> >> + clock-output-names = "cam_mclk_a", "cam_mclk_b";
> >>
> >> pinctrl-names = "default";
> >> pinctrl-0 = <&cam_port_a_clk_active>;
> >>
> >> + status = "okay";
> >> + #address-cells = <1>;
> >> + #size-cells = <1>;
> >>
> >> /* parallel camera ports */
> >> parallel-ports {
--
Regards,
Laurent Pinchart
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