Hi Sascha
On Tue, 30 Apr 2013, Sascha Hauer wrote:
> 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.
I've already proposed a fix for this and Laurent has proposed a simplified
version.
Thanks
Guennadi
>
> Sascha
>
>
> --
> Pengutronix e.K. | |
> Industrial Linux Solutions | http://www.pengutronix.de/ |
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>
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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