Currently if generic_buffer is invoked without first enabling any
channels in scan_elements/*_en, it will fail unable to enable the
buffer because bytes_per_datum inside the kernel will be zero if
no channels are available.
It is implied that the user of the program should enable channels
manually or with a script before executing generic_buffer.
Be more helpful by stopping execution if no enabled channels can
be found, and print a helptext that will tell you what is wrong
and what needs to be done.
Signed-off-by: Linus Walleij <firstname.lastname@example.org>
Acked-by: Hartmut Knaack <email@example.com>
Signed-off-by: Jonathan Cameron <firstname.lastname@example.org>