On Mon, Dec 25, 2017 at 09:58:02AM +0100, Ondřej Jirman wrote: > Hello, > > On Mon, Dec 25, 2017 at 11:15:26AM +0800, Yong wrote: > > Hi, > > > > On Fri, 22 Dec 2017 14:46:48 +0100 > > Ondřej Jirman <megous@xxxxxxxxxx> wrote: > > > > > Hello, > > > > > > Yong Deng píše v Pá 22. 12. 2017 v 17:32 +0800: > > > > > > > > Test input 0: > > > > > > > > Control ioctls: > > > > test VIDIOC_QUERY_EXT_CTRL/QUERYMENU: OK (Not Supported) > > > > test VIDIOC_QUERYCTRL: OK (Not Supported) > > > > test VIDIOC_G/S_CTRL: OK (Not Supported) > > > > test VIDIOC_G/S/TRY_EXT_CTRLS: OK (Not Supported) > > > > test VIDIOC_(UN)SUBSCRIBE_EVENT/DQEVENT: OK (Not Supported) > > > > test VIDIOC_G/S_JPEGCOMP: OK (Not Supported) > > > > Standard Controls: 0 Private Controls: 0 > > > > > > I'm not sure if your driver passes control queries to the subdev. It > > > did not originally, and I'm not sure you picked up the change from my > > > version of the driver. "Not supported" here seems to indicate that it > > > does not. > > > > > > I'd be interested what's the recommended practice here. It sure helps > > > with some apps that expect to be able to modify various input controls > > > directly on the /dev/video# device. These are then supported out of the > > > box. > > > > > > It's a one-line change. See: > > > > > > https://www.kernel.org/doc/html/latest/media/kapi/v4l2-controls.html#in > > > heriting-controls > > > > I think this is a feature and not affect the driver's main function. > > I just focused on making the CSI main function to work properly in > > the initial version. Is this feature mandatory or most commonly used? > > I grepped the platform/ code and it seems, that inheriting controls > from subdevs is pretty common for input drivers. (there are varying > approaches though, some inherit by hand in the link function, some > just register and empty ctrl_handler on the v4l2_dev and leave the > rest to the core). > > Practically, I haven't found a common app that would allow me to enter > both /dev/video0 and /dev/v4l-subdevX. I'm sure anyone can write one > themselves, but it would be better if current controls were available > at the /dev/video0 device automatically. > > It's much simpler for the userspace apps than the alternative, which > is trying to identify the correct subdev that is currently > associated with the CSI driver at runtime, which is not exactly > straightforward and requires much more code, than a few lines in > the kernel, that are required to inherit controls: And it becomes much more complicated once you have the same controls on the v4l2 device and subdevice, which is not that uncommon. Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
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