On Mo, 2023-03-20 at 13:47 +0100, Jacopo Mondi wrote: > Hi Philipp > > On Mon, Mar 20, 2023 at 12:26:26PM +0100, Philipp Zabel wrote: > > On Mo, 2023-03-20 at 11:55 +0200, Laurent Pinchart wrote: > > > 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(). > > > > The IPU driver doesn't call get_mbus_config, the CSI-2 RX driver does > > Am I confusing IPU CSI with CSI-2 ? > https://elixir.bootlin.com/linux/latest/source/drivers/staging/media/imx/imx-media-csi.c#L211 What the eyesight ... Sorry for the confusion. You are right, it's right there. Yes, that is IPU CSI calling get_mbus_config. I had git grepped for get_mbus_config this morning, and was convinced I only found the call in imx-media-csi2, which is where the number of lanes is evaluated. The call in imx-media-csi.c is used to determine whether the sensor is parallel or CSI-2 and whether the CSI has to operate in bypass mode (for 16-bit parallel bus). regards Philipp
