Hello, > -----Original Message----- > From: linux-media-owner@xxxxxxxxxxxxxxx [mailto:linux-media- > owner@xxxxxxxxxxxxxxx] On Behalf Of Laurent Pinchart > Sent: Friday, July 23, 2010 3:01 PM > To: Linux Media Mailing List > Cc: Sakari Ailus; Guennadi Liakhovetski > Subject: [RFC] Per-subdev, host-specific data > > Hi everybody, > > Trying to implement support for multiple sensors connected to the same > OMAP3 > ISP input (all but one of the sensors need to be kept in reset > obviously), I > need to associate host-specific data to the sensor subdevs. > > The terms host and bridge are considered as synonyms in the rest of > this e- > mail. > > The OMAP3 ISP platform data has interface configuration parameters for > the two > CSI2 (a and c), CCP2 and parallel interfaces. The parameters are used > to > configure the bus when a sensor is selected. To support multiple > sensors on > the same input, the parameters need to be specified per-sensor, and not > ISP- > wide. > > No issue in the platform data. Board codes declare an array of > structures that > embed a struct v4l2_subdev_i2c_board_info instance and an OMAP3 ISP- > specific > interface configuration structure. > > At runtime, when a sensor is selected, I need to access the OMAP3 ISP- > specific > interface configuration structure for the selected sensor. At that > point all I > have is a v4l2_subdev structure pointer, without a way to get back to > the > interface configuration structure. > > The only point in the code where the v4l2_subdev and the interface > configuration data are both known and could be linked together is in > the host > driver's probe function, where the v4l2_subdev instances are created. I > have > two solutions there: > > - store the v4l2_subdev pointer and the interface configuration data > pointer > in a host-specific array, and perform a an array lookup operation at > runtime > with the v4l2_subdev pointer as a key > > - add a void *host_priv field to the v4l2_subdev structure, store the > interface configuration data pointer in that field, and use the field > at > runtime > > The second solution seems cleaner but requires an additional field in > v4l2_subdev. Opinions and other comments will be appreciated. > I like the solution with an additional void *host_priv field, it could also possibly be useful for the notify() callback to v4l2_subdev parent. On our SoCs we also need some camera host interface specific data to be attached to image sensor subdevice and later passed to host driver. So host_priv field in v4l2_subdev would be nice feature to have. > -- > Regards, > > Laurent Pinchart > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" > in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html Regards, -- Sylwester Nawrocki Samsung Poland R&D Center -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
