Hi Prabhakar, On Sunday 30 November 2014 21:30:35 Prabhakar Lad wrote: > On Sun, Nov 30, 2014 at 9:16 PM, Laurent Pinchart wrote: > > On Sunday 30 November 2014 21:05:50 Prabhakar Lad wrote: > >> On Sat, Nov 29, 2014 at 7:12 PM, Laurent Pinchart wrote: > >> > Hi Prabhakar, > >> > >> [Snip] > >> > >>>>> Sure. That's a better choice than removing the config option > >>>>> dependency of the fields struct v4l2_subdev. > >>> > >>> Decoupling CONFIG_VIDEO_V4L2_SUBDEV_API from the availability of the > >>> in-kernel pad format and selection rectangles helpers is definitely a > >>> good idea. I was thinking about decoupling the try format and > >>> rectangles from v4l2_subdev_fh by creating a kind of configuration store > >>> structure to store them, and embedding that structure in v4l2_subdev_fh. > >>> The pad-level operations would then take a pointer to the configuration > >>> store instead of the v4l2_subdev_fh. Bridge drivers that want to > >>> implement TRY_FMT based on pad-level operations would create a > >>> configuration store, use the pad-level operations, and destroy the > >>> configuration store. The userspace subdev API would use the > >>> configuration store from the file handle. > >> > >> are planning to work/post any time soon ? Or are you OK with suggestion > >> from Hans ? > > > > I have no plan to work on that myself now, I was hoping you could > > implement it ;-) > > OK will implement it. > > Can you please elaborate a more on this "The userspace subdev API would use > the configuration store from the file handle." Basically, 1. Create a subdev pad configuration store structure to store the formats and selection rectangles for each pad. 2. Embed an instance of that structure in v4l2_subdev_fh. 3. Modify the subdev pad ops to take a configuration store pointer instead of a file handle pointer. The userspace API implementation (v4l2-subdev.c) would then pass &fh->store to the pad operations instead of fh. Bridge drivers that need to implement TRY_FMT on top of pad ops would create a temporary store (or temporary stores when multiple subsdevs are involved), call the pad ops with a pointer to the temporary store to propagate TRY formats, destroy the store(s) and return the resulting format. Is that clear ? -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
