On Mon, 2017-03-13 at 13:27 +0000, Russell King - ARM Linux wrote: > On Mon, Mar 13, 2017 at 03:16:48PM +0200, Sakari Ailus wrote: > > The vast majority of existing drivers do not implement them nor the user > > space expects having to set them. Making that mandatory would break existing > > user space. > > > > In addition, that does not belong to link validation either: link validation > > should only include static properties of the link that are required for > > correct hardware operation. Frame rate is not such property: hardware that > > supports the MC interface generally does not recognise such concept (with > > the exception of some sensors). Additionally, it is dynamic: the frame rate > > can change during streaming, making its validation at streamon time useless. > > So how do we configure the CSI, which can do frame skipping? > > With what you're proposing, it means it's possible to configure the > camera sensor source pad to do 50fps. Configure the CSI sink pad to > an arbitary value, such as 30fps, and configure the CSI source pad to > 15fps. > > What you actually get out of the CSI is 25fps, which bears very little > with the actual values used on the CSI source pad. > > You could say "CSI should ask the camera sensor" - well, that's fine > if it's immediately downstream, but otherwise we'd need to go walking > down the graph to find something that resembles its source - there may > be mux and CSI2 interface subdev blocks in that path. Or we just accept > that frame rates are completely arbitary and bear no useful meaning what > so ever. Which would include the frame interval returned by VIDIOC_G_PARM on the connected video device, as that gets its information from the CSI output pad's frame interval. regards Philipp _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
