Hi Ricardo, On 10-Nov-24 5:04 PM, Ricardo Ribalda wrote: > On Sun, 10 Nov 2024 at 16:14, Laurent Pinchart > <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: <snip> >>> Can we start powering up the device during try/set fmt and then >>> implement the format caching as an improvement? >> >> This sounds worth trying. We'll need to test it on a wide range of >> devices though, both internal and external. Ack, as mentioned in the other mail which I just send I think this is worth trying. > We still need a plan for asynchronous controls. As I mentioned in that other email I think we can do the same there. So basically delay powering up the camera from /dev/video# open till the first moment we actually need to communicate to the camera and track per file-handle if we did a usb_autopm_get_interface() for that file-handle and if yes, then do the put-interface on file-handle close. > And we have to decide if we stop supporting the uvc button (maybe we > can start by moving USB_VIDEO_CLASS_INPUT_EVDEV to staging and see > what happens?) As I mentioned in other threads I do not think that the button only working changing from: "only works when /dev/video# is open" to: "only works when streaming from /dev/video#" (or actually only works when some action on the camera which requires it to be powered-on has been done). is a big deal, since most apps which open /dev/video# for a longer time will almost always do so to actually do something with the camera, at which point the button will work just as before. And for apps which only do a short-lived open of /dev/video# the button does not work with the current code either. TL;DR: IMHO it is fine if the button only works when streaming. Regards, Hans
