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 <manivannan.sadhasivam@xxxxxxxxxx> > >>>>>> --- > >>>>>> .../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 <manivannan.sadhasivam@xxxxxxxxxx> > >>>>>> + > >>>>>> +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. -- Regards, Laurent Pinchart
