Hi Russell,

On Tue, Aug 13, 2019 at 12:38:46PM +0100, Russell King - ARM Linux admin wrote:

On Tue, Aug 06, 2019 at 06:39:36PM +0530, Manivannan Sadhasivam wrote:

quoted

+Required Properties:
+- compatible: Should be "sony,imx290"
+- reg: I2C bus address of the device
+- clocks: Reference to the xclk clock.
+- clock-names: Should be "xclk".
+- clock-frequency: Frequency of the xclk clock.

Driver code:

+       ret = of_property_read_u32(dev->of_node, "clock-frequency", &xclk_freq);+       if (ret) {
+               dev_err(dev, "Could not get xclk frequency\n");
+               return ret;
+       }
+
+       /* external clock must be 37.125 MHz */
+       if (xclk_freq != 37125000) {
+               dev_err(dev, "External clock frequency %u is not supported\n",
+                       xclk_freq);
+               return -EINVAL;
+       }

So, only 37125000 is supported - is that not worth mentioning in this
description?  Is this a hard requirement of the sensor?  If so, why
does it need to be mentioned in the DT binding?

The driver only supports a particular frequency, but the sensor is not
limited to that. Unfortunately this is not uncommon for camera sensors, for
the vendors often provide register settings for a given configuration only
(external clock frequency, number of CSI-2 lanes, CSI-2 bus frequency,
image cropping, binning etc.).

That still doesn't mean there are no alternative configurations for
different external clock frequencies, or that there could not be a driver
that was able to configure the sensor to use a given frequency.

-- 
Regards,

Sakari Ailus

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