Hi Mark,
Thanks for your review.
On 18/03/14 11:02, Mark Rutland wrote:
> On Tue, Mar 11, 2014 at 04:34:30PM +0000, Sylwester Nawrocki wrote:
>> > This patch documents following updates of the Exynos4 SoC camera subsystem
>> > devicetree binding:
>> >
>> > - addition of #clock-cells and clock-output-names properties to 'camera'
>> > node - these are now needed so the image sensor sub-devices can reference
>> > clocks provided by the camera host interface,
>> > - dropped a note about required clock-frequency properties at the
>> > image sensor nodes; the sensor devices can now control their clock
>> > explicitly through the clk API and there is no need to require this
>> > property in the camera host interface binding.
>> >
>> > Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
>> > ---
>> > Changes since v7:
>> > - dropped a note about clock-frequency property in sensor nodes.
>> >
>> > Changes since v6:
>> > - #clock-cells, clock-output-names documented as mandatory properties;
>> > - renamed "cam_mclk_{a,b}" to "cam_{a,b}_clkout in the example dts,
>> > this now matches changes in exynos4.dtsi further in the patch series;
>> > - marked "samsung,camclk-out" property as deprecated.
>> >
>> > Changes since v5:
>> > - none.
>> >
>> > Changes since v4:
>> > - dropped a requirement of specific order of values in clocks/
>> > clock-names properties (Mark) and reference to clock-names in
>> > clock-output-names property description (Mark).
>> > ---
>> > .../devicetree/bindings/media/samsung-fimc.txt | 44 +++++++++++++-------
>> > 1 file changed, 29 insertions(+), 15 deletions(-)
>> >
>> > diff --git a/Documentation/devicetree/bindings/media/samsung-fimc.txt b/Documentation/devicetree/bindings/media/samsung-fimc.txt
>> > index 96312f6..922d6f8 100644
>> > --- a/Documentation/devicetree/bindings/media/samsung-fimc.txt
>> > +++ b/Documentation/devicetree/bindings/media/samsung-fimc.txt
>> > @@ -15,11 +15,21 @@ Common 'camera' node
>> >
>> > Required properties:
>> >
>> > -- compatible : must be "samsung,fimc", "simple-bus"
>
> While it was already the case, why is "samsung,fimc" also a simple bus?
IIRC the main reason was to have children automatically instantiated
in Linux, also "samsung,fimc" is a master node gathering the all related
camera subsystem memory mapped IP blocks.
> If it has any properties which are required for the correct use of the
> child nodes, it is _not_ a simple-bus.
Then this can be considered a separate issue, and could be addressed
in a separate patch ?
>> > -- clocks : list of clock specifiers, corresponding to entries in
>> > - the clock-names property;
>> > -- clock-names : must contain "sclk_cam0", "sclk_cam1", "pxl_async0",
>> > - "pxl_async1" entries, matching entries in the clocks property.
>> > +- compatible: must be "samsung,fimc", "simple-bus"
>> > +- clocks: list of clock specifiers, corresponding to entries in
>> > + the clock-names property;
>> > +- clock-names : must contain "sclk_cam0", "sclk_cam1", "pxl_async0",
>> > + "pxl_async1" entries, matching entries in the clocks property.
>> > +
>> > +- #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.
>
> And if we're adding more stuff required by child nodes it's definitely
> not a simple-bus.
>
> Get rid of simple-bus. Get the driver for "samsung,fimc" to probe its
> children once it has set up.
>
> Apologies for the late reply, and sorry to have to be negative on this.
While I agree with you that the "simple-bus" might not be a best idea,
I can't see how your suggestion could be now implemented in Linux, since
AFAIK there is no API like of_platform_unpopulate(), so device objects
can be removed upon the driver module removal.
--
Regards,
Sylwester
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