[v4,1/2] dt-bindings: media: i2c: Add IMX296 CMOS sensor binding

Commit Message

Manivannan Sadhasivam Oct. 30, 2019, 9:49 a.m. UTC

Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
add MAINTAINERS entry for the binding and driver.

Signed-off-by: Manivannan Sadhasivam <[e-mail]>
---
 .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
 MAINTAINERS                                   |  8 ++
 2 files changed, 102 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml

Comments

Sakari Ailus Oct. 30, 2019, 11:53 a.m. UTC | #1

Hi Nabuvannan,

On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> add MAINTAINERS entry for the binding and driver.
> 
> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> ---
>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
>  MAINTAINERS                                   |  8 ++
>  2 files changed, 102 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> new file mode 100644
> index 000000000000..c04ec2203268
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> @@ -0,0 +1,94 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> +
> +maintainers:
> +  - Manivannan Sadhasivam <[e-mail]>
> +
> +description: |-
> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> +  features a global shutter with variable charge-integration time. It is
> +  programmable through I2C and 4-wire interfaces. The sensor output is
> +  available via CSI-2 serial data output (1 Lane).
> +
> +properties:
> +  compatible:
> +    const: sony,imx296
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    description:
> +      Input clock for the sensor.
> +    items:
> +      - const: mclk
> +
> +  clock-frequency:
> +    description:
> +      Frequency of the mclk clock in Hertz.
> +
> +  vddo-supply:
> +    description:
> +      Definition of the regulator used as interface power supply.
> +
> +  vdda-supply:
> +    description:
> +      Definition of the regulator used as analog power supply.
> +
> +  vddd-supply:
> +    description:
> +      Definition of the regulator used as digital power supply.
> +
> +  reset-gpios:
> +    description:
> +      The phandle and specifier for the GPIO that controls sensor reset.
> +    maxItems: 1
> +
> +  port: true

You're missing "type: object" under port.

Manivannan Sadhasivam Oct. 30, 2019, 12:01 p.m. UTC | #2

Hi Sakari,

On Wed, Oct 30, 2019 at 01:53:28PM +0200, Sakari Ailus wrote:
> Hi Nabuvannan,
> 
> On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> > Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> > add MAINTAINERS entry for the binding and driver.
> > 
> > Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> > ---
> >  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> >  MAINTAINERS                                   |  8 ++
> >  2 files changed, 102 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > new file mode 100644
> > index 000000000000..c04ec2203268
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > @@ -0,0 +1,94 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> > +
> > +maintainers:
> > +  - Manivannan Sadhasivam <[e-mail]>
> > +
> > +description: |-
> > +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> > +  sensor with square pixel array and 1.58 M effective pixels. This chip
> > +  features a global shutter with variable charge-integration time. It is
> > +  programmable through I2C and 4-wire interfaces. The sensor output is
> > +  available via CSI-2 serial data output (1 Lane).
> > +
> > +properties:
> > +  compatible:
> > +    const: sony,imx296
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    maxItems: 1
> > +
> > +  clock-names:
> > +    description:
> > +      Input clock for the sensor.
> > +    items:
> > +      - const: mclk
> > +
> > +  clock-frequency:
> > +    description:
> > +      Frequency of the mclk clock in Hertz.
> > +
> > +  vddo-supply:
> > +    description:
> > +      Definition of the regulator used as interface power supply.
> > +
> > +  vdda-supply:
> > +    description:
> > +      Definition of the regulator used as analog power supply.
> > +
> > +  vddd-supply:
> > +    description:
> > +      Definition of the regulator used as digital power supply.
> > +
> > +  reset-gpios:
> > +    description:
> > +      The phandle and specifier for the GPIO that controls sensor reset.
> > +    maxItems: 1
> > +
> > +  port: true
> 
> You're missing "type: object" under port.
> 

I did that intentionally, since there are other places where I can see the
"type" field not specified. So, I was not sure about that. Most of the
display bindings don't specify "type" and they are most available ones.
I don't think the "port" property differs between cameras and displays.
So I went with that.

Thanks,
Mani

> -- 
> Regards,
> 
> Sakari Ailus

Laurent Pinchart Oct. 31, 2019, 1:15 p.m. UTC | #3

Hi Mani,

Thank you for the patch.

On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> add MAINTAINERS entry for the binding and driver.
> 
> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> ---
>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
>  MAINTAINERS                                   |  8 ++
>  2 files changed, 102 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> new file mode 100644
> index 000000000000..c04ec2203268
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> @@ -0,0 +1,94 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> +
> +maintainers:
> +  - Manivannan Sadhasivam <[e-mail]>
> +
> +description: |-
> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> +  features a global shutter with variable charge-integration time. It is
> +  programmable through I2C and 4-wire interfaces. The sensor output is
> +  available via CSI-2 serial data output (1 Lane).
> +
> +properties:
> +  compatible:
> +    const: sony,imx296
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    description:
> +      Input clock for the sensor.
> +    items:
> +      - const: mclk

The pin is named INCK, let's name the clock accordingly.

> +  clock-frequency:
> +    description:
> +      Frequency of the mclk clock in Hertz.

This shouldn't be needed, you can retrieve the clock frequency at
runtime from the clock source.

> +  vddo-supply:
> +    description:
> +      Definition of the regulator used as interface power supply.
> +
> +  vdda-supply:
> +    description:
> +      Definition of the regulator used as analog power supply.
> +
> +  vddd-supply:
> +    description:
> +      Definition of the regulator used as digital power supply.

Do we really need three regulators ? I agree that the sensor has three
power rails, but aren't they usually powered by regulators that are
tied together, without individual control ? The IMX926 specifications
require the three power supplies to raise within 200ms, which we should
be able to ensure in software. What does your board use, does it have
multiple GPIOs to control each power supply ? If not I wonder if we
could just define vddd-supply now, and add vdda-supply and vddo-supply
later if we need to support systems that can control the supplies
individually.

> +  reset-gpios:
> +    description:
> +      The phandle and specifier for the GPIO that controls sensor reset.
> +    maxItems: 1
> +
> +  port: true
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - clock-names
> +  - clock-frequency
> +  - vddo-supply
> +  - vdda-supply
> +  - vddd-supply
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    imx296: camera-sensor@1a {
> +        compatible = "sony,imx296";
> +        reg = <0x1a>;
> +        reset-gpios = <&msmgpio 35 GPIO_ACTIVE_LOW>;
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&camera_rear_default>;
> +        clocks = <&gcc 90>;
> +        clock-names = "mclk";
> +        clock-frequency = <37125000>;
> +        vddo-supply = <&camera_vddo_1v8>;
> +        vdda-supply = <&camera_vdda_3v3>;
> +        vddd-supply = <&camera_vddd_1v2>;
> +
> +        port {
> +            imx296_ep: endpoint {
> +                remote-endpoint = <&csiphy0_ep>;
> +            };
> +        };
> +    };
> +
> +...
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 55199ef7fa74..51194bb2c392 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15140,6 +15140,14 @@ S:	Maintained
>  F:	drivers/media/i2c/imx274.c
>  F:	Documentation/devicetree/bindings/media/i2c/imx274.txt
>  
> +SONY IMX296 SENSOR DRIVER
> +M:	Manivannan Sadhasivam <[e-mail]>
> +L:	[e-mail]
> +T:	git git://linuxtv.org/media_tree.git
> +S:	Maintained
> +F:	drivers/media/i2c/imx296.c
> +F:	Documentation/devicetree/bindings/media/i2c/imx296.yaml
> +
>  SONY IMX319 SENSOR DRIVER
>  M:	Bingbu Cao <[e-mail]>
>  L:	[e-mail]

Manivannan Sadhasivam Oct. 31, 2019, 1:45 p.m. UTC | #4

Hi Laurent,

On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote:
> Hi Mani,
> 
> Thank you for the patch.
> 
> On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> > Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> > add MAINTAINERS entry for the binding and driver.
> > 
> > Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> > ---
> >  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> >  MAINTAINERS                                   |  8 ++
> >  2 files changed, 102 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > new file mode 100644
> > index 000000000000..c04ec2203268
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > @@ -0,0 +1,94 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> > +
> > +maintainers:
> > +  - Manivannan Sadhasivam <[e-mail]>
> > +
> > +description: |-
> > +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> > +  sensor with square pixel array and 1.58 M effective pixels. This chip
> > +  features a global shutter with variable charge-integration time. It is
> > +  programmable through I2C and 4-wire interfaces. The sensor output is
> > +  available via CSI-2 serial data output (1 Lane).
> > +
> > +properties:
> > +  compatible:
> > +    const: sony,imx296
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    maxItems: 1
> > +
> > +  clock-names:
> > +    description:
> > +      Input clock for the sensor.
> > +    items:
> > +      - const: mclk
> 
> The pin is named INCK, let's name the clock accordingly.
>

Okay, I thought generic names are preferred here!
 
> > +  clock-frequency:
> > +    description:
> > +      Frequency of the mclk clock in Hertz.
> 
> This shouldn't be needed, you can retrieve the clock frequency at
> runtime from the clock source.
> 

Unless the clock source is a fixed one! What if the clock source comes from
SoC? We need to set the rate, right?

> > +  vddo-supply:
> > +    description:
> > +      Definition of the regulator used as interface power supply.
> > +
> > +  vdda-supply:
> > +    description:
> > +      Definition of the regulator used as analog power supply.
> > +
> > +  vddd-supply:
> > +    description:
> > +      Definition of the regulator used as digital power supply.
> 
> Do we really need three regulators ? I agree that the sensor has three
> power rails, but aren't they usually powered by regulators that are
> tied together, without individual control ? The IMX926 specifications
> require the three power supplies to raise within 200ms, which we should
> be able to ensure in software. What does your board use, does it have
> multiple GPIOs to control each power supply ? If not I wonder if we
> could just define vddd-supply now, and add vdda-supply and vddo-supply
> later if we need to support systems that can control the supplies
> individually.
> 

The whole power supply model is a bit rotten. In my case, there are 3 different
regulators used with no software control. So, I can't control the rise time
(I assume that they are handled by the external power regulator itself).

So to be sane, I just documented with the assumption of fixed-regulators.

Thanks,
Mani
> > +  reset-gpios:
> > +    description:
> > +      The phandle and specifier for the GPIO that controls sensor reset.
> > +    maxItems: 1
> > +
> > +  port: true
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - clocks
> > +  - clock-names
> > +  - clock-frequency
> > +  - vddo-supply
> > +  - vdda-supply
> > +  - vddd-supply
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +
> > +    imx296: camera-sensor@1a {
> > +        compatible = "sony,imx296";
> > +        reg = <0x1a>;
> > +        reset-gpios = <&msmgpio 35 GPIO_ACTIVE_LOW>;
> > +        pinctrl-names = "default";
> > +        pinctrl-0 = <&camera_rear_default>;
> > +        clocks = <&gcc 90>;
> > +        clock-names = "mclk";
> > +        clock-frequency = <37125000>;
> > +        vddo-supply = <&camera_vddo_1v8>;
> > +        vdda-supply = <&camera_vdda_3v3>;
> > +        vddd-supply = <&camera_vddd_1v2>;
> > +
> > +        port {
> > +            imx296_ep: endpoint {
> > +                remote-endpoint = <&csiphy0_ep>;
> > +            };
> > +        };
> > +    };
> > +
> > +...
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 55199ef7fa74..51194bb2c392 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -15140,6 +15140,14 @@ S:	Maintained
> >  F:	drivers/media/i2c/imx274.c
> >  F:	Documentation/devicetree/bindings/media/i2c/imx274.txt
> >  
> > +SONY IMX296 SENSOR DRIVER
> > +M:	Manivannan Sadhasivam <[e-mail]>
> > +L:	[e-mail]
> > +T:	git git://linuxtv.org/media_tree.git
> > +S:	Maintained
> > +F:	drivers/media/i2c/imx296.c
> > +F:	Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > +
> >  SONY IMX319 SENSOR DRIVER
> >  M:	Bingbu Cao <[e-mail]>
> >  L:	[e-mail]
> 
> -- 
> Regards,
> 
> Laurent Pinchart

Laurent Pinchart Oct. 31, 2019, 2:11 p.m. UTC | #5

Hi Mani,

On Thu, Oct 31, 2019 at 07:15:12PM +0530, Manivannan Sadhasivam wrote:
> On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote:
> > On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> >> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> >> add MAINTAINERS entry for the binding and driver.
> >> 
> >> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> >> ---
> >>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> >>  MAINTAINERS                                   |  8 ++
> >>  2 files changed, 102 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >> 
> >> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >> new file mode 100644
> >> index 000000000000..c04ec2203268
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >> @@ -0,0 +1,94 @@
> >> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> >> +%YAML 1.2
> >> +---
> >> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >> +
> >> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> >> +
> >> +maintainers:
> >> +  - Manivannan Sadhasivam <[e-mail]>
> >> +
> >> +description: |-
> >> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> >> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> >> +  features a global shutter with variable charge-integration time. It is
> >> +  programmable through I2C and 4-wire interfaces. The sensor output is
> >> +  available via CSI-2 serial data output (1 Lane).
> >> +
> >> +properties:
> >> +  compatible:
> >> +    const: sony,imx296
> >> +
> >> +  reg:
> >> +    maxItems: 1
> >> +
> >> +  clocks:
> >> +    maxItems: 1
> >> +
> >> +  clock-names:
> >> +    description:
> >> +      Input clock for the sensor.
> >> +    items:
> >> +      - const: mclk
> > 
> > The pin is named INCK, let's name the clock accordingly.
> 
> Okay, I thought generic names are preferred here!
>  
> >> +  clock-frequency:
> >> +    description:
> >> +      Frequency of the mclk clock in Hertz.
> > 
> > This shouldn't be needed, you can retrieve the clock frequency at
> > runtime from the clock source.
> 
> Unless the clock source is a fixed one! What if the clock source comes from
> SoC? We need to set the rate, right?

In that case, if you want to hardcode the clock in DT, the preferred way
is to use the assigned-clock-rates property. Otherwise, if the driver
requires a specific clock frequency, it's better to hardcode it in the
driver itself. In this specific case, I think assigned-clock-rates is
best as the device can support three different clock frequencies.

> >> +  vddo-supply:
> >> +    description:
> >> +      Definition of the regulator used as interface power supply.
> >> +
> >> +  vdda-supply:
> >> +    description:
> >> +      Definition of the regulator used as analog power supply.
> >> +
> >> +  vddd-supply:
> >> +    description:
> >> +      Definition of the regulator used as digital power supply.
> > 
> > Do we really need three regulators ? I agree that the sensor has three
> > power rails, but aren't they usually powered by regulators that are
> > tied together, without individual control ? The IMX926 specifications
> > require the three power supplies to raise within 200ms, which we should
> > be able to ensure in software. What does your board use, does it have
> > multiple GPIOs to control each power supply ? If not I wonder if we
> > could just define vddd-supply now, and add vdda-supply and vddo-supply
> > later if we need to support systems that can control the supplies
> > individually.
> 
> The whole power supply model is a bit rotten. In my case, there are 3 different
> regulators used with no software control. So, I can't control the rise time
> (I assume that they are handled by the external power regulator itself).
> 
> So to be sane, I just documented with the assumption of fixed-regulators.

Should we then go for one supply, and add the other two when (and if)
needed ?

> >> +  reset-gpios:
> >> +    description:
> >> +      The phandle and specifier for the GPIO that controls sensor reset.
> >> +    maxItems: 1
> >> +
> >> +  port: true
> >> +
> >> +required:
> >> +  - compatible
> >> +  - reg
> >> +  - clocks
> >> +  - clock-names
> >> +  - clock-frequency
> >> +  - vddo-supply
> >> +  - vdda-supply
> >> +  - vddd-supply
> >> +
> >> +additionalProperties: false
> >> +
> >> +examples:
> >> +  - |
> >> +    #include <dt-bindings/gpio/gpio.h>
> >> +
> >> +    imx296: camera-sensor@1a {
> >> +        compatible = "sony,imx296";
> >> +        reg = <0x1a>;
> >> +        reset-gpios = <&msmgpio 35 GPIO_ACTIVE_LOW>;
> >> +        pinctrl-names = "default";
> >> +        pinctrl-0 = <&camera_rear_default>;
> >> +        clocks = <&gcc 90>;
> >> +        clock-names = "mclk";
> >> +        clock-frequency = <37125000>;
> >> +        vddo-supply = <&camera_vddo_1v8>;
> >> +        vdda-supply = <&camera_vdda_3v3>;
> >> +        vddd-supply = <&camera_vddd_1v2>;
> >> +
> >> +        port {
> >> +            imx296_ep: endpoint {
> >> +                remote-endpoint = <&csiphy0_ep>;
> >> +            };
> >> +        };
> >> +    };
> >> +
> >> +...
> >> diff --git a/MAINTAINERS b/MAINTAINERS
> >> index 55199ef7fa74..51194bb2c392 100644
> >> --- a/MAINTAINERS
> >> +++ b/MAINTAINERS
> >> @@ -15140,6 +15140,14 @@ S:	Maintained
> >>  F:	drivers/media/i2c/imx274.c
> >>  F:	Documentation/devicetree/bindings/media/i2c/imx274.txt
> >>  
> >> +SONY IMX296 SENSOR DRIVER
> >> +M:	Manivannan Sadhasivam <[e-mail]>
> >> +L:	[e-mail]
> >> +T:	git git://linuxtv.org/media_tree.git
> >> +S:	Maintained
> >> +F:	drivers/media/i2c/imx296.c
> >> +F:	Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >> +
> >>  SONY IMX319 SENSOR DRIVER
> >>  M:	Bingbu Cao <[e-mail]>
> >>  L:	[e-mail]

Sakari Ailus Oct. 31, 2019, 2:28 p.m. UTC | #6

Hi Laurent,

On Thu, Oct 31, 2019 at 04:11:41PM +0200, Laurent Pinchart wrote:
> Hi Mani,
> 
> On Thu, Oct 31, 2019 at 07:15:12PM +0530, Manivannan Sadhasivam wrote:
> > On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote:
> > > On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> > >> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> > >> add MAINTAINERS entry for the binding and driver.
> > >> 
> > >> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> > >> ---
> > >>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> > >>  MAINTAINERS                                   |  8 ++
> > >>  2 files changed, 102 insertions(+)
> > >>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >> 
> > >> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >> new file mode 100644
> > >> index 000000000000..c04ec2203268
> > >> --- /dev/null
> > >> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >> @@ -0,0 +1,94 @@
> > >> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > >> +%YAML 1.2
> > >> +---
> > >> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> > >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > >> +
> > >> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> > >> +
> > >> +maintainers:
> > >> +  - Manivannan Sadhasivam <[e-mail]>
> > >> +
> > >> +description: |-
> > >> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> > >> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> > >> +  features a global shutter with variable charge-integration time. It is
> > >> +  programmable through I2C and 4-wire interfaces. The sensor output is
> > >> +  available via CSI-2 serial data output (1 Lane).
> > >> +
> > >> +properties:
> > >> +  compatible:
> > >> +    const: sony,imx296
> > >> +
> > >> +  reg:
> > >> +    maxItems: 1
> > >> +
> > >> +  clocks:
> > >> +    maxItems: 1
> > >> +
> > >> +  clock-names:
> > >> +    description:
> > >> +      Input clock for the sensor.
> > >> +    items:
> > >> +      - const: mclk
> > > 
> > > The pin is named INCK, let's name the clock accordingly.
> > 
> > Okay, I thought generic names are preferred here!
> >  
> > >> +  clock-frequency:
> > >> +    description:
> > >> +      Frequency of the mclk clock in Hertz.
> > > 
> > > This shouldn't be needed, you can retrieve the clock frequency at
> > > runtime from the clock source.
> > 
> > Unless the clock source is a fixed one! What if the clock source comes from
> > SoC? We need to set the rate, right?
> 
> In that case, if you want to hardcode the clock in DT, the preferred way
> is to use the assigned-clock-rates property. Otherwise, if the driver
> requires a specific clock frequency, it's better to hardcode it in the
> driver itself. In this specific case, I think assigned-clock-rates is
> best as the device can support three different clock frequencies.

Just note that if ACPI support is added to the sensor driver, you'll need
the clock-frequency property again, for that's the only way how the driver
will get the clock frequency.

This is certainly not something that has to be taken into account in DT
bindings, but in any case it'll add some lines of code in the driver which
are not very useful.

Manivannan Sadhasivam Oct. 31, 2019, 2:58 p.m. UTC | #7

Hi Laurent,

On Thu, Oct 31, 2019 at 04:11:41PM +0200, Laurent Pinchart wrote:
> Hi Mani,
> 
> On Thu, Oct 31, 2019 at 07:15:12PM +0530, Manivannan Sadhasivam wrote:
> > On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote:
> > > On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> > >> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> > >> add MAINTAINERS entry for the binding and driver.
> > >> 
> > >> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> > >> ---
> > >>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> > >>  MAINTAINERS                                   |  8 ++
> > >>  2 files changed, 102 insertions(+)
> > >>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >> 
> > >> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >> new file mode 100644
> > >> index 000000000000..c04ec2203268
> > >> --- /dev/null
> > >> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >> @@ -0,0 +1,94 @@
> > >> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > >> +%YAML 1.2
> > >> +---
> > >> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> > >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > >> +
> > >> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> > >> +
> > >> +maintainers:
> > >> +  - Manivannan Sadhasivam <[e-mail]>
> > >> +
> > >> +description: |-
> > >> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> > >> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> > >> +  features a global shutter with variable charge-integration time. It is
> > >> +  programmable through I2C and 4-wire interfaces. The sensor output is
> > >> +  available via CSI-2 serial data output (1 Lane).
> > >> +
> > >> +properties:
> > >> +  compatible:
> > >> +    const: sony,imx296
> > >> +
> > >> +  reg:
> > >> +    maxItems: 1
> > >> +
> > >> +  clocks:
> > >> +    maxItems: 1
> > >> +
> > >> +  clock-names:
> > >> +    description:
> > >> +      Input clock for the sensor.
> > >> +    items:
> > >> +      - const: mclk
> > > 
> > > The pin is named INCK, let's name the clock accordingly.
> > 
> > Okay, I thought generic names are preferred here!
> >  
> > >> +  clock-frequency:
> > >> +    description:
> > >> +      Frequency of the mclk clock in Hertz.
> > > 
> > > This shouldn't be needed, you can retrieve the clock frequency at
> > > runtime from the clock source.
> > 
> > Unless the clock source is a fixed one! What if the clock source comes from
> > SoC? We need to set the rate, right?
> 
> In that case, if you want to hardcode the clock in DT, the preferred way
> is to use the assigned-clock-rates property. Otherwise, if the driver
> requires a specific clock frequency, it's better to hardcode it in the
> driver itself. In this specific case, I think assigned-clock-rates is
> best as the device can support three different clock frequencies.
> 

Agree. assigned-clock* properties makes sense for multiple frequencies. In
my driver, I only used one frequency so I was happy with clock-frequency :)

> > >> +  vddo-supply:
> > >> +    description:
> > >> +      Definition of the regulator used as interface power supply.
> > >> +
> > >> +  vdda-supply:
> > >> +    description:
> > >> +      Definition of the regulator used as analog power supply.
> > >> +
> > >> +  vddd-supply:
> > >> +    description:
> > >> +      Definition of the regulator used as digital power supply.
> > > 
> > > Do we really need three regulators ? I agree that the sensor has three
> > > power rails, but aren't they usually powered by regulators that are
> > > tied together, without individual control ? The IMX926 specifications
> > > require the three power supplies to raise within 200ms, which we should
> > > be able to ensure in software. What does your board use, does it have
> > > multiple GPIOs to control each power supply ? If not I wonder if we
> > > could just define vddd-supply now, and add vdda-supply and vddo-supply
> > > later if we need to support systems that can control the supplies
> > > individually.
> > 
> > The whole power supply model is a bit rotten. In my case, there are 3 different
> > regulators used with no software control. So, I can't control the rise time
> > (I assume that they are handled by the external power regulator itself).
> > 
> > So to be sane, I just documented with the assumption of fixed-regulators.
> 
> Should we then go for one supply, and add the other two when (and if)
> needed ?
> 

I'm not really sure if we should use one power supply here. The single power
supply configuration is not true for all cases. And following what other
sensors are using, I'd prefer to have 3 individual power supplies.

Thanks,
Mani

> > >> +  reset-gpios:
> > >> +    description:
> > >> +      The phandle and specifier for the GPIO that controls sensor reset.
> > >> +    maxItems: 1
> > >> +
> > >> +  port: true
> > >> +
> > >> +required:
> > >> +  - compatible
> > >> +  - reg
> > >> +  - clocks
> > >> +  - clock-names
> > >> +  - clock-frequency
> > >> +  - vddo-supply
> > >> +  - vdda-supply
> > >> +  - vddd-supply
> > >> +
> > >> +additionalProperties: false
> > >> +
> > >> +examples:
> > >> +  - |
> > >> +    #include <dt-bindings/gpio/gpio.h>
> > >> +
> > >> +    imx296: camera-sensor@1a {
> > >> +        compatible = "sony,imx296";
> > >> +        reg = <0x1a>;
> > >> +        reset-gpios = <&msmgpio 35 GPIO_ACTIVE_LOW>;
> > >> +        pinctrl-names = "default";
> > >> +        pinctrl-0 = <&camera_rear_default>;
> > >> +        clocks = <&gcc 90>;
> > >> +        clock-names = "mclk";
> > >> +        clock-frequency = <37125000>;
> > >> +        vddo-supply = <&camera_vddo_1v8>;
> > >> +        vdda-supply = <&camera_vdda_3v3>;
> > >> +        vddd-supply = <&camera_vddd_1v2>;
> > >> +
> > >> +        port {
> > >> +            imx296_ep: endpoint {
> > >> +                remote-endpoint = <&csiphy0_ep>;
> > >> +            };
> > >> +        };
> > >> +    };
> > >> +
> > >> +...
> > >> diff --git a/MAINTAINERS b/MAINTAINERS
> > >> index 55199ef7fa74..51194bb2c392 100644
> > >> --- a/MAINTAINERS
> > >> +++ b/MAINTAINERS
> > >> @@ -15140,6 +15140,14 @@ S:	Maintained
> > >>  F:	drivers/media/i2c/imx274.c
> > >>  F:	Documentation/devicetree/bindings/media/i2c/imx274.txt
> > >>  
> > >> +SONY IMX296 SENSOR DRIVER
> > >> +M:	Manivannan Sadhasivam <[e-mail]>
> > >> +L:	[e-mail]
> > >> +T:	git git://linuxtv.org/media_tree.git
> > >> +S:	Maintained
> > >> +F:	drivers/media/i2c/imx296.c
> > >> +F:	Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >> +
> > >>  SONY IMX319 SENSOR DRIVER
> > >>  M:	Bingbu Cao <[e-mail]>
> > >>  L:	[e-mail]
> 
> -- 
> Regards,
> 
> Laurent Pinchart

Laurent Pinchart Oct. 31, 2019, 4:54 p.m. UTC | #8

Hi Sakari,

On Thu, Oct 31, 2019 at 04:28:17PM +0200, Sakari Ailus wrote:
> On Thu, Oct 31, 2019 at 04:11:41PM +0200, Laurent Pinchart wrote:
> > On Thu, Oct 31, 2019 at 07:15:12PM +0530, Manivannan Sadhasivam wrote:
> >> On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote:
> >>> On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> >>>> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> >>>> add MAINTAINERS entry for the binding and driver.
> >>>> 
> >>>> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> >>>> ---
> >>>>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> >>>>  MAINTAINERS                                   |  8 ++
> >>>>  2 files changed, 102 insertions(+)
> >>>>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >>>> 
> >>>> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >>>> new file mode 100644
> >>>> index 000000000000..c04ec2203268
> >>>> --- /dev/null
> >>>> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >>>> @@ -0,0 +1,94 @@
> >>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> >>>> +%YAML 1.2
> >>>> +---
> >>>> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> >>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>>> +
> >>>> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> >>>> +
> >>>> +maintainers:
> >>>> +  - Manivannan Sadhasivam <[e-mail]>
> >>>> +
> >>>> +description: |-
> >>>> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> >>>> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> >>>> +  features a global shutter with variable charge-integration time. It is
> >>>> +  programmable through I2C and 4-wire interfaces. The sensor output is
> >>>> +  available via CSI-2 serial data output (1 Lane).
> >>>> +
> >>>> +properties:
> >>>> +  compatible:
> >>>> +    const: sony,imx296
> >>>> +
> >>>> +  reg:
> >>>> +    maxItems: 1
> >>>> +
> >>>> +  clocks:
> >>>> +    maxItems: 1
> >>>> +
> >>>> +  clock-names:
> >>>> +    description:
> >>>> +      Input clock for the sensor.
> >>>> +    items:
> >>>> +      - const: mclk
> >>> 
> >>> The pin is named INCK, let's name the clock accordingly.
> >> 
> >> Okay, I thought generic names are preferred here!
> >>  
> >>>> +  clock-frequency:
> >>>> +    description:
> >>>> +      Frequency of the mclk clock in Hertz.
> >>> 
> >>> This shouldn't be needed, you can retrieve the clock frequency at
> >>> runtime from the clock source.
> >> 
> >> Unless the clock source is a fixed one! What if the clock source comes from
> >> SoC? We need to set the rate, right?
> > 
> > In that case, if you want to hardcode the clock in DT, the preferred way
> > is to use the assigned-clock-rates property. Otherwise, if the driver
> > requires a specific clock frequency, it's better to hardcode it in the
> > driver itself. In this specific case, I think assigned-clock-rates is
> > best as the device can support three different clock frequencies.
> 
> Just note that if ACPI support is added to the sensor driver, you'll need
> the clock-frequency property again, for that's the only way how the driver
> will get the clock frequency.

Why is so ? Why can't we implement of assigned-clock-rates for ACPI ?

> This is certainly not something that has to be taken into account in DT
> bindings, but in any case it'll add some lines of code in the driver which
> are not very useful.

Sakari Ailus Oct. 31, 2019, 5:08 p.m. UTC | #9

Hi Laurent,

On Thu, Oct 31, 2019 at 06:54:44PM +0200, Laurent Pinchart wrote:
> Hi Sakari,
> 
> On Thu, Oct 31, 2019 at 04:28:17PM +0200, Sakari Ailus wrote:
> > On Thu, Oct 31, 2019 at 04:11:41PM +0200, Laurent Pinchart wrote:
> > > On Thu, Oct 31, 2019 at 07:15:12PM +0530, Manivannan Sadhasivam wrote:
> > >> On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote:
> > >>> On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> > >>>> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> > >>>> add MAINTAINERS entry for the binding and driver.
> > >>>> 
> > >>>> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> > >>>> ---
> > >>>>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> > >>>>  MAINTAINERS                                   |  8 ++
> > >>>>  2 files changed, 102 insertions(+)
> > >>>>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >>>> 
> > >>>> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >>>> new file mode 100644
> > >>>> index 000000000000..c04ec2203268
> > >>>> --- /dev/null
> > >>>> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >>>> @@ -0,0 +1,94 @@
> > >>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > >>>> +%YAML 1.2
> > >>>> +---
> > >>>> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> > >>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > >>>> +
> > >>>> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> > >>>> +
> > >>>> +maintainers:
> > >>>> +  - Manivannan Sadhasivam <[e-mail]>
> > >>>> +
> > >>>> +description: |-
> > >>>> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> > >>>> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> > >>>> +  features a global shutter with variable charge-integration time. It is
> > >>>> +  programmable through I2C and 4-wire interfaces. The sensor output is
> > >>>> +  available via CSI-2 serial data output (1 Lane).
> > >>>> +
> > >>>> +properties:
> > >>>> +  compatible:
> > >>>> +    const: sony,imx296
> > >>>> +
> > >>>> +  reg:
> > >>>> +    maxItems: 1
> > >>>> +
> > >>>> +  clocks:
> > >>>> +    maxItems: 1
> > >>>> +
> > >>>> +  clock-names:
> > >>>> +    description:
> > >>>> +      Input clock for the sensor.
> > >>>> +    items:
> > >>>> +      - const: mclk
> > >>> 
> > >>> The pin is named INCK, let's name the clock accordingly.
> > >> 
> > >> Okay, I thought generic names are preferred here!
> > >>  
> > >>>> +  clock-frequency:
> > >>>> +    description:
> > >>>> +      Frequency of the mclk clock in Hertz.
> > >>> 
> > >>> This shouldn't be needed, you can retrieve the clock frequency at
> > >>> runtime from the clock source.
> > >> 
> > >> Unless the clock source is a fixed one! What if the clock source comes from
> > >> SoC? We need to set the rate, right?
> > > 
> > > In that case, if you want to hardcode the clock in DT, the preferred way
> > > is to use the assigned-clock-rates property. Otherwise, if the driver
> > > requires a specific clock frequency, it's better to hardcode it in the
> > > driver itself. In this specific case, I think assigned-clock-rates is
> > > best as the device can support three different clock frequencies.
> > 
> > Just note that if ACPI support is added to the sensor driver, you'll need
> > the clock-frequency property again, for that's the only way how the driver
> > will get the clock frequency.
> 
> Why is so ? Why can't we implement of assigned-clock-rates for ACPI ?

ACPI doesn't deal with clocks as such. So there's also no ACPI defined way
to access clocks specifically, including the frequency --- instead the
clock is controlled by an AML methods which implement power on and off
sequences for the device.

Laurent Pinchart Nov. 4, 2019, 7:02 p.m. UTC | #10

Hi Sakari,

On Thu, Oct 31, 2019 at 07:08:37PM +0200, Sakari Ailus wrote:
> On Thu, Oct 31, 2019 at 06:54:44PM +0200, Laurent Pinchart wrote:
> > On Thu, Oct 31, 2019 at 04:28:17PM +0200, Sakari Ailus wrote:
> >> On Thu, Oct 31, 2019 at 04:11:41PM +0200, Laurent Pinchart wrote:
> >>> On Thu, Oct 31, 2019 at 07:15:12PM +0530, Manivannan Sadhasivam wrote:
> >>>> On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote:
> >>>>> On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> >>>>>> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> >>>>>> add MAINTAINERS entry for the binding and driver.
> >>>>>> 
> >>>>>> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> >>>>>> ---
> >>>>>>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> >>>>>>  MAINTAINERS                                   |  8 ++
> >>>>>>  2 files changed, 102 insertions(+)
> >>>>>>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >>>>>> 
> >>>>>> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >>>>>> new file mode 100644
> >>>>>> index 000000000000..c04ec2203268
> >>>>>> --- /dev/null
> >>>>>> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >>>>>> @@ -0,0 +1,94 @@
> >>>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> >>>>>> +%YAML 1.2
> >>>>>> +---
> >>>>>> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> >>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>>>>> +
> >>>>>> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> >>>>>> +
> >>>>>> +maintainers:
> >>>>>> +  - Manivannan Sadhasivam <[e-mail]>
> >>>>>> +
> >>>>>> +description: |-
> >>>>>> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> >>>>>> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> >>>>>> +  features a global shutter with variable charge-integration time. It is
> >>>>>> +  programmable through I2C and 4-wire interfaces. The sensor output is
> >>>>>> +  available via CSI-2 serial data output (1 Lane).
> >>>>>> +
> >>>>>> +properties:
> >>>>>> +  compatible:
> >>>>>> +    const: sony,imx296
> >>>>>> +
> >>>>>> +  reg:
> >>>>>> +    maxItems: 1
> >>>>>> +
> >>>>>> +  clocks:
> >>>>>> +    maxItems: 1
> >>>>>> +
> >>>>>> +  clock-names:
> >>>>>> +    description:
> >>>>>> +      Input clock for the sensor.
> >>>>>> +    items:
> >>>>>> +      - const: mclk
> >>>>> 
> >>>>> The pin is named INCK, let's name the clock accordingly.
> >>>> 
> >>>> Okay, I thought generic names are preferred here!
> >>>>  
> >>>>>> +  clock-frequency:
> >>>>>> +    description:
> >>>>>> +      Frequency of the mclk clock in Hertz.
> >>>>> 
> >>>>> This shouldn't be needed, you can retrieve the clock frequency at
> >>>>> runtime from the clock source.
> >>>> 
> >>>> Unless the clock source is a fixed one! What if the clock source comes from
> >>>> SoC? We need to set the rate, right?
> >>> 
> >>> In that case, if you want to hardcode the clock in DT, the preferred way
> >>> is to use the assigned-clock-rates property. Otherwise, if the driver
> >>> requires a specific clock frequency, it's better to hardcode it in the
> >>> driver itself. In this specific case, I think assigned-clock-rates is
> >>> best as the device can support three different clock frequencies.
> >> 
> >> Just note that if ACPI support is added to the sensor driver, you'll need
> >> the clock-frequency property again, for that's the only way how the driver
> >> will get the clock frequency.
> > 
> > Why is so ? Why can't we implement of assigned-clock-rates for ACPI ?
> 
> ACPI doesn't deal with clocks as such. So there's also no ACPI defined way
> to access clocks specifically, including the frequency --- instead the
> clock is controlled by an AML methods which implement power on and off
> sequences for the device.

It's a shortcoming of ACPI, which should be addressed at the ACPI level.
We shouldn't polute the DT bindings with a clock-frequency property for
this reason.

Sakari Ailus Nov. 4, 2019, 9:30 p.m. UTC | #11

Hi Laurent,

On Mon, Nov 04, 2019 at 09:02:01PM +0200, Laurent Pinchart wrote:
> Hi Sakari,
> 
> On Thu, Oct 31, 2019 at 07:08:37PM +0200, Sakari Ailus wrote:
> > On Thu, Oct 31, 2019 at 06:54:44PM +0200, Laurent Pinchart wrote:
> > > On Thu, Oct 31, 2019 at 04:28:17PM +0200, Sakari Ailus wrote:
> > >> On Thu, Oct 31, 2019 at 04:11:41PM +0200, Laurent Pinchart wrote:
> > >>> On Thu, Oct 31, 2019 at 07:15:12PM +0530, Manivannan Sadhasivam wrote:
> > >>>> On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote:
> > >>>>> On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> > >>>>>> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> > >>>>>> add MAINTAINERS entry for the binding and driver.
> > >>>>>> 
> > >>>>>> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> > >>>>>> ---
> > >>>>>>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> > >>>>>>  MAINTAINERS                                   |  8 ++
> > >>>>>>  2 files changed, 102 insertions(+)
> > >>>>>>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >>>>>> 
> > >>>>>> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >>>>>> new file mode 100644
> > >>>>>> index 000000000000..c04ec2203268
> > >>>>>> --- /dev/null
> > >>>>>> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > >>>>>> @@ -0,0 +1,94 @@
> > >>>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > >>>>>> +%YAML 1.2
> > >>>>>> +---
> > >>>>>> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> > >>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > >>>>>> +
> > >>>>>> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> > >>>>>> +
> > >>>>>> +maintainers:
> > >>>>>> +  - Manivannan Sadhasivam <[e-mail]>
> > >>>>>> +
> > >>>>>> +description: |-
> > >>>>>> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> > >>>>>> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> > >>>>>> +  features a global shutter with variable charge-integration time. It is
> > >>>>>> +  programmable through I2C and 4-wire interfaces. The sensor output is
> > >>>>>> +  available via CSI-2 serial data output (1 Lane).
> > >>>>>> +
> > >>>>>> +properties:
> > >>>>>> +  compatible:
> > >>>>>> +    const: sony,imx296
> > >>>>>> +
> > >>>>>> +  reg:
> > >>>>>> +    maxItems: 1
> > >>>>>> +
> > >>>>>> +  clocks:
> > >>>>>> +    maxItems: 1
> > >>>>>> +
> > >>>>>> +  clock-names:
> > >>>>>> +    description:
> > >>>>>> +      Input clock for the sensor.
> > >>>>>> +    items:
> > >>>>>> +      - const: mclk
> > >>>>> 
> > >>>>> The pin is named INCK, let's name the clock accordingly.
> > >>>> 
> > >>>> Okay, I thought generic names are preferred here!
> > >>>>  
> > >>>>>> +  clock-frequency:
> > >>>>>> +    description:
> > >>>>>> +      Frequency of the mclk clock in Hertz.
> > >>>>> 
> > >>>>> This shouldn't be needed, you can retrieve the clock frequency at
> > >>>>> runtime from the clock source.
> > >>>> 
> > >>>> Unless the clock source is a fixed one! What if the clock source comes from
> > >>>> SoC? We need to set the rate, right?
> > >>> 
> > >>> In that case, if you want to hardcode the clock in DT, the preferred way
> > >>> is to use the assigned-clock-rates property. Otherwise, if the driver
> > >>> requires a specific clock frequency, it's better to hardcode it in the
> > >>> driver itself. In this specific case, I think assigned-clock-rates is
> > >>> best as the device can support three different clock frequencies.
> > >> 
> > >> Just note that if ACPI support is added to the sensor driver, you'll need
> > >> the clock-frequency property again, for that's the only way how the driver
> > >> will get the clock frequency.
> > > 
> > > Why is so ? Why can't we implement of assigned-clock-rates for ACPI ?
> > 
> > ACPI doesn't deal with clocks as such. So there's also no ACPI defined way
> > to access clocks specifically, including the frequency --- instead the
> > clock is controlled by an AML methods which implement power on and off
> > sequences for the device.
> 
> It's a shortcoming of ACPI, which should be addressed at the ACPI level.
> We shouldn't polute the DT bindings with a clock-frequency property for
> this reason.

It's really not a shortcoming but a design decision: what belongs to the
scope of the firmware? And in this case system and device power management
implementation is included. I do not believe this will be revisited in any
foreseeable future, i.e. there will be no clock control interface for ACPI.

Explicitly stating the frequency also has an added benefit: the driver
can be certain that the given frequency is intended to be used on the
board. Otherwise the frequency could have been changed by e.g. another
driver. This does matter, as the frequency determines which link
frequencies can be achieved, and as the two effectively have to be
compliant, an unintended external clock frequency also means there will be
no match between possible link frequencies and configured link frequencies.

I.e. no images to capture either.

That said, I don't know if this has been a practical issue in the past.

Laurent Pinchart Nov. 4, 2019, 10 p.m. UTC | #12

Hi Sakari,

On Mon, Nov 04, 2019 at 11:30:32PM +0200, Sakari Ailus wrote:
> On Mon, Nov 04, 2019 at 09:02:01PM +0200, Laurent Pinchart wrote:
> > On Thu, Oct 31, 2019 at 07:08:37PM +0200, Sakari Ailus wrote:
> >> On Thu, Oct 31, 2019 at 06:54:44PM +0200, Laurent Pinchart wrote:
> >>> On Thu, Oct 31, 2019 at 04:28:17PM +0200, Sakari Ailus wrote:
> >>>> On Thu, Oct 31, 2019 at 04:11:41PM +0200, Laurent Pinchart wrote:
> >>>>> On Thu, Oct 31, 2019 at 07:15:12PM +0530, Manivannan Sadhasivam wrote:
> >>>>>> On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote:
> >>>>>>> On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> >>>>>>>> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> >>>>>>>> add MAINTAINERS entry for the binding and driver.
> >>>>>>>> 
> >>>>>>>> Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> >>>>>>>> ---
> >>>>>>>>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> >>>>>>>>  MAINTAINERS                                   |  8 ++
> >>>>>>>>  2 files changed, 102 insertions(+)
> >>>>>>>>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >>>>>>>> 
> >>>>>>>> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >>>>>>>> new file mode 100644
> >>>>>>>> index 000000000000..c04ec2203268
> >>>>>>>> --- /dev/null
> >>>>>>>> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> >>>>>>>> @@ -0,0 +1,94 @@
> >>>>>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> >>>>>>>> +%YAML 1.2
> >>>>>>>> +---
> >>>>>>>> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> >>>>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>>>>>>> +
> >>>>>>>> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> >>>>>>>> +
> >>>>>>>> +maintainers:
> >>>>>>>> +  - Manivannan Sadhasivam <[e-mail]>
> >>>>>>>> +
> >>>>>>>> +description: |-
> >>>>>>>> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> >>>>>>>> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> >>>>>>>> +  features a global shutter with variable charge-integration time. It is
> >>>>>>>> +  programmable through I2C and 4-wire interfaces. The sensor output is
> >>>>>>>> +  available via CSI-2 serial data output (1 Lane).
> >>>>>>>> +
> >>>>>>>> +properties:
> >>>>>>>> +  compatible:
> >>>>>>>> +    const: sony,imx296
> >>>>>>>> +
> >>>>>>>> +  reg:
> >>>>>>>> +    maxItems: 1
> >>>>>>>> +
> >>>>>>>> +  clocks:
> >>>>>>>> +    maxItems: 1
> >>>>>>>> +
> >>>>>>>> +  clock-names:
> >>>>>>>> +    description:
> >>>>>>>> +      Input clock for the sensor.
> >>>>>>>> +    items:
> >>>>>>>> +      - const: mclk
> >>>>>>> 
> >>>>>>> The pin is named INCK, let's name the clock accordingly.
> >>>>>> 
> >>>>>> Okay, I thought generic names are preferred here!
> >>>>>>  
> >>>>>>>> +  clock-frequency:
> >>>>>>>> +    description:
> >>>>>>>> +      Frequency of the mclk clock in Hertz.
> >>>>>>> 
> >>>>>>> This shouldn't be needed, you can retrieve the clock frequency at
> >>>>>>> runtime from the clock source.
> >>>>>> 
> >>>>>> Unless the clock source is a fixed one! What if the clock source comes from
> >>>>>> SoC? We need to set the rate, right?
> >>>>> 
> >>>>> In that case, if you want to hardcode the clock in DT, the preferred way
> >>>>> is to use the assigned-clock-rates property. Otherwise, if the driver
> >>>>> requires a specific clock frequency, it's better to hardcode it in the
> >>>>> driver itself. In this specific case, I think assigned-clock-rates is
> >>>>> best as the device can support three different clock frequencies.
> >>>> 
> >>>> Just note that if ACPI support is added to the sensor driver, you'll need
> >>>> the clock-frequency property again, for that's the only way how the driver
> >>>> will get the clock frequency.
> >>> 
> >>> Why is so ? Why can't we implement of assigned-clock-rates for ACPI ?
> >> 
> >> ACPI doesn't deal with clocks as such. So there's also no ACPI defined way
> >> to access clocks specifically, including the frequency --- instead the
> >> clock is controlled by an AML methods which implement power on and off
> >> sequences for the device.
> > 
> > It's a shortcoming of ACPI, which should be addressed at the ACPI level.
> > We shouldn't polute the DT bindings with a clock-frequency property for
> > this reason.
> 
> It's really not a shortcoming but a design decision: what belongs to the
> scope of the firmware? And in this case system and device power management
> implementation is included. I do not believe this will be revisited in any
> foreseeable future, i.e. there will be no clock control interface for ACPI.

I'm not saying there's a need to control clocks, but if the driver of
the camera sensor needs to know the frequency of an externally supplied
clock, the firmware should give a way for the operating system to
retrieve the clock frequency. Doing so with a clock-frequency in the
sensor node is a hack to work around a limitation of ACPI, as the Linux
model to retrieve clock frequencies it to interogate the clock provider.

> Explicitly stating the frequency also has an added benefit: the driver
> can be certain that the given frequency is intended to be used on the
> board. Otherwise the frequency could have been changed by e.g. another
> driver. This does matter, as the frequency determines which link
> frequencies can be achieved, and as the two effectively have to be
> compliant, an unintended external clock frequency also means there will be
> no match between possible link frequencies and configured link frequencies.

This doesn't solve anything, quite the contrary. With
assigned-clock-rates the frequency is set once in the firmware, the
operating system configures the clock provider to set the frequency, and
the sensor driver then queries the provider. There's a single source of
clock frequency information. With clock-frequency, you have two sources
of information, the value of the property and the value set when
programming the clock provider in the firmware (either in the BIOS/UEFI,
or in the ACPI DSDT AML). That's a chance to get it wrong, and we both
know how reliable firmware is.

Furthermore, the clock-frequency property requires drivers to be
informed of firmware details. On DT-based systems they should use
clk_get_rate(), while on ACPI-based systems they should read the
clock-frequency property. If you want to support ACPI, this should be
hidden by the firmware, with retrieval of clock frequency from the
firmware handled in core code.

One option would be to create fixed clocks automatically for ACPI
devices that report clock frequency through an ACPI-specific (as in
defined outside of the ACPI standard, through DSD for instance) mean.
Drivers would then be able to call clk_get() and clk_get_rate().

> I.e. no images to capture either.
> 
> That said, I don't know if this has been a practical issue in the past.

Rob Herring (Arm) Nov. 5, 2019, 1:43 a.m. UTC | #13

On Wed, Oct 30, 2019 at 05:31:05PM +0530, Manivannan Sadhasivam wrote:
> Hi Sakari,
> 
> On Wed, Oct 30, 2019 at 01:53:28PM +0200, Sakari Ailus wrote:
> > Hi Nabuvannan,
> > 
> > On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> > > Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> > > add MAINTAINERS entry for the binding and driver.
> > > 
> > > Signed-off-by: Manivannan Sadhasivam <[e-mail]>
> > > ---
> > >  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
> > >  MAINTAINERS                                   |  8 ++
> > >  2 files changed, 102 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > > new file mode 100644
> > > index 000000000000..c04ec2203268
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> > > @@ -0,0 +1,94 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> > > +
> > > +maintainers:
> > > +  - Manivannan Sadhasivam <[e-mail]>
> > > +
> > > +description: |-
> > > +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> > > +  sensor with square pixel array and 1.58 M effective pixels. This chip
> > > +  features a global shutter with variable charge-integration time. It is
> > > +  programmable through I2C and 4-wire interfaces. The sensor output is
> > > +  available via CSI-2 serial data output (1 Lane).
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: sony,imx296
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  clocks:
> > > +    maxItems: 1
> > > +
> > > +  clock-names:
> > > +    description:
> > > +      Input clock for the sensor.
> > > +    items:
> > > +      - const: mclk
> > > +
> > > +  clock-frequency:
> > > +    description:
> > > +      Frequency of the mclk clock in Hertz.
> > > +
> > > +  vddo-supply:
> > > +    description:
> > > +      Definition of the regulator used as interface power supply.
> > > +
> > > +  vdda-supply:
> > > +    description:
> > > +      Definition of the regulator used as analog power supply.
> > > +
> > > +  vddd-supply:
> > > +    description:
> > > +      Definition of the regulator used as digital power supply.
> > > +
> > > +  reset-gpios:
> > > +    description:
> > > +      The phandle and specifier for the GPIO that controls sensor reset.
> > > +    maxItems: 1
> > > +
> > > +  port: true
> > 
> > You're missing "type: object" under port.
> > 
> 
> I did that intentionally, since there are other places where I can see the
> "type" field not specified. So, I was not sure about that. Most of the
> display bindings don't specify "type" and they are most available ones.
> I don't think the "port" property differs between cameras and displays.
> So I went with that.

The difference is the panel bindings have a common schema included 
which defines 'port' at least as a node. I don't think an include would 
help too much here, so probably best to add 'type: object' for now. 
Either way, this may change once video-interfaces.txt is converted if 
any of those properties apply here.

Either way:

Reviewed-by: Rob Herring <[e-mail]>

Rob

Patch

diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
new file mode 100644
index 000000000000..c04ec2203268
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
@@ -0,0 +1,94 @@ 
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
+
+maintainers:
+  - Manivannan Sadhasivam <[e-mail]>
+
+description: |-
+  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
+  sensor with square pixel array and 1.58 M effective pixels. This chip
+  features a global shutter with variable charge-integration time. It is
+  programmable through I2C and 4-wire interfaces. The sensor output is
+  available via CSI-2 serial data output (1 Lane).
+
+properties:
+  compatible:
+    const: sony,imx296
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    description:
+      Input clock for the sensor.
+    items:
+      - const: mclk
+
+  clock-frequency:
+    description:
+      Frequency of the mclk clock in Hertz.
+
+  vddo-supply:
+    description:
+      Definition of the regulator used as interface power supply.
+
+  vdda-supply:
+    description:
+      Definition of the regulator used as analog power supply.
+
+  vddd-supply:
+    description:
+      Definition of the regulator used as digital power supply.
+
+  reset-gpios:
+    description:
+      The phandle and specifier for the GPIO that controls sensor reset.
+    maxItems: 1
+
+  port: true
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - clock-frequency
+  - vddo-supply
+  - vdda-supply
+  - vddd-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    imx296: camera-sensor@1a {
+        compatible = "sony,imx296";
+        reg = <0x1a>;
+        reset-gpios = <&msmgpio 35 GPIO_ACTIVE_LOW>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&camera_rear_default>;
+        clocks = <&gcc 90>;
+        clock-names = "mclk";
+        clock-frequency = <37125000>;
+        vddo-supply = <&camera_vddo_1v8>;
+        vdda-supply = <&camera_vdda_3v3>;
+        vddd-supply = <&camera_vddd_1v2>;
+
+        port {
+            imx296_ep: endpoint {
+                remote-endpoint = <&csiphy0_ep>;
+            };
+        };
+    };
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 55199ef7fa74..51194bb2c392 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15140,6 +15140,14 @@  S:	Maintained
 F:	drivers/media/i2c/imx274.c
 F:	Documentation/devicetree/bindings/media/i2c/imx274.txt
 
+SONY IMX296 SENSOR DRIVER
+M:	Manivannan Sadhasivam <[e-mail]>
+L:	[e-mail]
+T:	git git://linuxtv.org/media_tree.git
+S:	Maintained
+F:	drivers/media/i2c/imx296.c
+F:	Documentation/devicetree/bindings/media/i2c/imx296.yaml
+
 SONY IMX319 SENSOR DRIVER
 M:	Bingbu Cao <[e-mail]>
 L:	[e-mail]