Hi Guennadi,
On Fri, Apr 12, 2013 at 05:40:22PM +0200, Guennadi Liakhovetski wrote:
> Currently bridge device drivers register devices for all subdevices
> synchronously, tupically, during their probing. E.g. if an I2C CMOS sensor
> is attached to a video bridge device, the bridge driver will create an I2C
> device and wait for the respective I2C driver to probe. This makes linking
> of devices straight forward, but this approach cannot be used with
> intrinsically asynchronous and unordered device registration systems like
> the Flattened Device Tree. To support such systems this patch adds an
> asynchronous subdevice registration framework to V4L2. To use it respective
> (e.g. I2C) subdevice drivers must register themselves with the framework.
> A bridge driver on the other hand must register notification callbacks,
> that will be called upon various related events.
>
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> ---
> +
> +static struct v4l2_async_subdev *v4l2_async_belongs(struct v4l2_async_notifier *notifier,
> + struct v4l2_async_subdev_list *asdl)
> +{
> + struct v4l2_subdev *sd = v4l2_async_to_subdev(asdl);
> + struct v4l2_async_subdev *asd = NULL;
> + bool (*match)(struct device *,
> + struct v4l2_async_hw_info *);
> +
> + list_for_each_entry (asd, ¬ifier->waiting, list) {
> + struct v4l2_async_hw_info *hw = &asd->hw;
> +
> + /* bus_type has been verified valid before */
> + switch (hw->bus_type) {
> + case V4L2_ASYNC_BUS_CUSTOM:
> + match = hw->match.custom.match;
> + if (!match)
> + /* Match always */
> + return asd;
> + break;
> + case V4L2_ASYNC_BUS_PLATFORM:
> + match = match_platform;
> + break;
> + case V4L2_ASYNC_BUS_I2C:
> + match = match_i2c;
> + break;
> + default:
> + /* Cannot happen, unless someone breaks us */
> + WARN_ON(true);
> + return NULL;
> + }
> +
> + if (match && match(sd->dev, hw))
> + break;
> + }
> +
> + return asd;
'asd' can never be NULL here. You have to explicitly return NULL when
leaving the loop without match.
Sascha
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