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>
diff --git a/tools/iio/generic_buffer.c b/tools/iio/generic_buffer.c
index 9f7b85b..01c4f67 100644
--- a/tools/iio/generic_buffer.c
+++ b/tools/iio/generic_buffer.c
@@ -328,6 +328,15 @@
"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.