PROBLEM: FB_BACKLIGHT prevents building module backlight.ko

Apologies if this is the wrong place to report a potential Kconfig
issue with fbdev.  Please let me know where I should move the
discussion in that case.

I'm trying to compile the backlight.ko module, by setting

| CONFIG_BACKLIGHT_CLASS_DEVICE=m

in my kernel `.config` file.

The `FB_BACKLIGHT=y` configuration (also present in my kernel config)
appears to override the `CONFIG_BACKLIGHT_CLASS_DEVICE` value above to
"y", and so the backlight.ko module does not get built.

It looks like this happens in the fbdev Kconfig, because if I change
`drivers/video/fbdev/Kconfig` as follows so that
`BACKLIGHT_CLASS_DEVICE` is a "depends on", rather than a "select", it
builds properly.  In that case `CONFIG_BACKLIGHT_CLASS_DEVICE=m` is
preserved.

| config FB_BACKLIGHT
|         bool
|         depends on FB
|         select BACKLIGHT_LCD_SUPPORT
|         depends on BACKLIGHT_CLASS_DEVICE
|         default n

Without the above change, my kernel config reverts to
`CONFIG_BACKLIGHT_CLASS_DEVICE=y` and the backlight.ko module is not
built.

I'm not entirely sure the "depends on" change is the right approach,
especially with menuconfig.  How best to fix this?

Thank you,
jpap