iio: generic_buffer: be helpful about enabling channels

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 <linus.walleij@linaro.org>
Acked-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Linus Walleij 2015-08-10 10:55:08 +02:00 committed by Jonathan Cameron
parent 672f93b604
commit 53dabafe1b

View file

@ -328,6 +328,15 @@ int main(int argc, char **argv)
"diag %s\n", dev_dir_name);
goto error_free_triggername;
}
if (!num_channels) {
fprintf(stderr,
"No channels are enabled, we have nothing to scan.\n");
fprintf(stderr, "Enable channels manually in "
FORMAT_SCAN_ELEMENTS_DIR
"/*_en and try again.\n", dev_dir_name);
ret = -ENOENT;
goto error_free_triggername;
}
/*
* Construct the directory name for the associated buffer.