Hi, On Tue 01 Dec 20, 13:12, Maxime Ripard wrote: > Hi, > > On Sat, Nov 28, 2020 at 03:28:27PM +0100, Paul Kocialkowski wrote: > > The A31 CSI controller supports a MIPI CSI-2 bridge input, which has > > its own dedicated port in the fwnode graph. > > > > Support for this input is added with this change: > > - two pads are defined for the media entity instead of one > > and only one needs to be connected at a time; > > - the pads currently match the fwnode graph representation; > > - links are created between our pads and the subdevs for each > > interface and are no longer immutable so that userspace can select > > which interface to use in case both are bound to a subdev; > > - fwnode endpoints are parsed and stored for each interface; > > - the active subdev (and fwnode endpoint) is retrieved when validating > > the media link at stream on time and cleared at stream off; > > - an error is raised if both links are active at the same time; > > - the MIPI interface bit is set if the MIPI CSI-2 bridge endpoint is > > active. > > > > In the future, the media entity representation might evolve to: > > - distinguish the internal parallel bridge and data formatter; > > - represent each of the 4 internal channels that can exist between > > the parallel bridge (for BT656 time-multiplex) and MIPI CSI-2 > > (internal channels can be mapped to virtual channels); > > - connect the controller's output to the ISP instead of its > > DMA engine. > > > > Finally note that the MIPI CSI-2 bridges should not be linked in > > the fwnode graph unless they have a sensor subdev attached. > > I'll leave most of the review to Laurent and Sakari, but I'm not quite > sure what you meant in the last paragraph. Did you mean that the > MIPI-CSI controller in the Allwinner SoC should only be linked if it has > a sensor attached, or did you mean that any MIPI-CSI2 bridge cannot be > attached to the controller? So the use of plural was a mistake and your first understanding is the correct one: if the bridge is linked to the CSI controller in the OF graph but the bridge doesn't have a sensor attached, the CSI controller driver will fail to probe, as far as I could see. I haven't investigated much but it looks like this is expected behavior. > Also, having somewhere (like your cover letter) the media-ctl setup you > tested with would be great. Understood! Cheers, Paul -- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com
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