Hi, Vladimir!

How do you do? :-)

On Tue, Feb 21, 2017 at 10:48:09PM +0200, Vladimir Zapolskiy wrote:

Hi Ramiro,

On 02/21/2017 10:13 PM, Ramiro Oliveira wrote:

quoted

Hi Vladimir,

Thank you for your feedback

On 2/21/2017 3:58 PM, Vladimir Zapolskiy wrote:

quoted

Hi Ramiro,

On 02/17/2017 03:14 PM, Ramiro Oliveira wrote:

quoted

Create device tree bindings documentation.

Signed-off-by: Ramiro Oliveira <roliveir-HKixBCOQz3hWk0Htik3J/w@public.gmane.org>
Acked-by: Rob Herring <redacted>
---
 .../devicetree/bindings/media/i2c/ov5647.txt       | 35 ++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/i2c/ov5647.txt

diff --git a/Documentation/devicetree/bindings/media/i2c/ov5647.txt b/Documentation/devicetree/bindings/media/i2c/ov5647.txt
new file mode 100644
index 000000000000..31956426d3b9
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/i2c/ov5647.txt

@@ -0,0 +1,35 @@
+Omnivision OV5647 raw image sensor
+---------------------------------
+
+OV5647 is a raw image sensor with MIPI CSI-2 and CCP2 image data interfaces
+and CCI (I2C compatible) control bus.
+
+Required properties:
+
+- compatible		: "ovti,ov5647".
+- reg			: I2C slave address of the sensor.
+- clocks		: Reference to the xclk clock.

Is "xclk" clock a pixel clock or something else?

It's an external oscillator.

hmm, I suppose a clock of any type could serve as a clock for the sensor.
It can be an external oscillator on a particular board, or it can be
something else on another board.

Any clock source could be used I presume.

Can you please describe what for does ov5647 sensor need this clock, what
is its function?

Camera modules (sensors) quite commonly require an external clock as they do
not have an oscillator on their own. A lot of devices under
Documentation/devicetree/bindings/media/i2c/ have similar properties.

quoted

quoted

quoted

+- clock-names		: Should be "xclk".

You can remove this property, because there is only one source clock.

Ok.

quoted

quoted

+- clock-frequency	: Frequency of the xclk clock.

And after the last updates in the driver this property can be removed as well.

But I'm still using clk_get_rate in the driver, if I remove the frequency here
the probing will fail.

I doubt it, there should be no connection between a custom "clock-frequency"
device tree property in a clock consumer device node and clk_get_rate() function
from the CCF, which takes a clock provider as its argument.

The purpose is to make sure the clock frequency is really usable for the
device, in this particular case the driver can work with one particular
frequency.

That said, the driver does not appear to use the property at the moment. It
should.

It'd be good to verify that the rate matches: clk_set_rate() is not
guaranteed to produce the requested clock rate, and the driver could
conceivably be updated with support for more frequencies. There are
typically a few frequencies that a SoC such a sensor is connected can
support, and 25 MHz is not one of the common frequencies. With this
property, the frequency would be always there explicitly.

quoted

quoted

quoted

+
+The common video interfaces bindings (see video-interfaces.txt) should be
+used to specify link to the image data receiver. The OV5647 device
+node should contain one 'port' child node with an 'endpoint' subnode.
+
+Example:
+
+	i2c@2000 {
+		...
+		ov: camera@36 {
+			compatible = "ovti,ov5647";
+			reg = <0x36>;
+			clocks = <&camera_clk>;
+			clock-names = "xclk";
+			clock-frequency = <25000000>;

When you remove two unused properties, please don't forget to update the
example.

Ok.

quoted

quoted

+			port {
+				camera_1: endpoint {
+					remote-endpoint = <&csi1_ep1>;
+				};
+			};
+		};
+	};

--

    ^
There's a space missing here.

With best wishes,
Vladimir

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ailus-X3B1VOXEql0@public.gmane.org	XMPP: sailus-PCDdDYkjdNMDXYZnReoRVg@public.gmane.org
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html