Re: [PATCH] staging: gpib: simplify and fix get_data_lines

[Dan Carpenter <dan.carpenter@linaro.org>]

On Wed, Aug 27, 2025 at 12:05:02AM +0200, Osama Abdelkader wrote:
> The function `get_data_lines()` in gpib_bitbang.c currently reads 8
> GPIO descriptors individually and combines them into a byte.
> This has two issues:
> 
>   * `gpiod_get_value()` returns an `int` which may be negative on
>     error. Assigning it directly into a `u8` may propagate unexpected
>     values. Masking ensures only the LSB is used.

Using the last bit in an error code is not really "error handling"...

What you could do instead would be something like:

	int ret;

	for (i = 0; i < 8; i++) {
		ret |= (gpiod_get_value(lines[i]) & 1) << i;
		if (ret < 0) {
			pr_err("something failed\n");
			return -EINVAL;
		}
	}

	return ~ret;

Which might also not be correct, but it's probably closer to being okay.

regards,
dan carpenter