Re: [PATCH] media: i2c: select V4L2_ASYNC where needed

[Sakari Ailus]

Hi Anrd,

On Mon, Sep 20, 2021 at 11:58:24AM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
> 
> I came across a link failure from randconfig builds:
> 
> x86_64-linux-ld: drivers/media/i2c/ths8200.o: in function `ths8200_remove':
> ths8200.c:(.text+0x491): undefined reference to `v4l2_async_unregister_subdev'
> x86_64-linux-ld: drivers/media/i2c/ths8200.o: in function `ths8200_probe':
> ths8200.c:(.text+0xe49): undefined reference to `v4l2_async_register_subdev'
> x86_64-linux-ld: drivers/media/i2c/tw9910.o: in function `tw9910_remove':
> tw9910.c:(.text+0x467): undefined reference to `v4l2_async_unregister_subdev'
> x86_64-linux-ld: drivers/media/i2c/tw9910.o: in function `tw9910_probe':
> tw9910.c:(.text+0x1123): undefined reference to `v4l2_async_register_subdev'
> 
> These clearly lack a 'select' statement, but I don't know why
> this started happening only now. I had a bit of a look around to find
> other configs that have the same problem, but could not come up with
> a reliable way and found nothing else through experimentation.
> It is likely that other symbols like these exist that need an extra
> select.
> 
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Probably this one:

commit ff3cc65cadb5d7333fde557b38cbb60b3a6cf496
Author: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Date:   Fri Mar 5 18:38:39 2021 +0100

    media: v4l: async, fwnode: Improve module organisation
    
    The V4L2 async framework is generally used with the V4L2 fwnode, which
    also depends on the former. There are a few exceptions but they are
    relatively few.
    
    At the same time there is a vast number of systems that need videodev
    module, but have no use for v4l2-async that's now part of videodev.
    
    In order to improve, split the v4l2-async into its own module. Selecting
    V4L2_FWNODE also selects V4L2_ASYNC.
    
    This also moves the initialisation of the debufs entries for async subdevs
    to loading of the v4l2-async module. The directory is named as
    "v4l2-async".
    
    Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
    Reviewed-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
    Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>

I think I must have missed some drivers using v4l2-async.

Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>

-- 
Sakari Ailus