On 12/02/2014 12:26 AM, Laurent Pinchart wrote: > 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. I wouldn't call it a 'store'. Just call it fmt_config or pad_config something like that. > > 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. That will work. I think this is a good approach and it shouldn't be too difficult. Regards, Hans -- 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
