On Mon, Mar 20, 2023 at 11:37:33AM +0200, Sakari Ailus wrote: > Hi Laurent, > > On Mon, Mar 20, 2023 at 11:26:02AM +0200, Laurent Pinchart wrote: > > In a (simplified) nutshell, > > > > ---------+ +----------+ +---------+ +-----+ +-----+ > > | Camera | --> | CSI-2 RX | --> | CSI2IPU | --> | Mux | --> | IPU | > > | Sensor | | | | Gasket | | | | | > > ---------+ +----------+ +---------+ +-----+ +-----+ > > Thank you, this is helpful. > > I suppose the mux here at least won't actively do anything to the data. So > presumably its endpoint won't contain the active configuration, but its > superset. > > > > > All those blocks, except for the gasket, have a node in DT. > > > > The IPU driver needs to know the number of CSI-2 data lanes, which is > > encoded in the data-lanes DT property present in both the sensor output > > endpoint and the CSI-2 RX input endpoint, but not the other endpoints in > > the pipeline. > > This doesn't yet explain why the sensor would need to implement > get_mbus_config if its bus configuration remains constant. If I recall correctly, the IPU driver calls .g_mbus_config() on the camera sensor to get the number of lanes, as it can't get it from its own endpoint. That's a hack, and as Jacopo proposed, calling .g_mbus_config() on the CSI-2 RX would be better, as the CSI-2 RX driver can then get the value from its own endpoint, without requiring all sensor drivers to implement .g_mbus_config(). > I suppose those blocks in between would probably need something to convey > their active configuration from upstream sub-devices. -- Regards, Laurent Pinchart
