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 <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. -- Sakari Ailus
