Re: [PATCH] iio: afe: rescale: Fix logic bug

[Liam Beguin <liambeguin@gmail.com>]

On Tue, May 24, 2022 at 09:54:48AM +0200, Linus Walleij wrote:
> When introducing support for processed channels I needed
> to invert the expression:
> 
>   if (!iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) ||
>       !iio_channel_has_info(schan, IIO_CHAN_INFO_SCALE))
>         dev_err(dev, "source channel does not support raw/scale\n");
> 
> To the inverse, meaning detect when we can usse raw+scale
> rather than when we can not. This was the result:
> 
>   if (iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) ||
>       iio_channel_has_info(schan, IIO_CHAN_INFO_SCALE))
>        dev_info(dev, "using raw+scale source channel\n");
> 
> Ooops. Spot the error. Yep old George Boole came up and bit me.
> That should be an &&.
> 
> The current code "mostly works" because we have not run into
> systems supporting only raw but not scale or only scale but not
> raw, and I doubt there are few using the rescaler on anything
> such, but let's fix the logic.

Maybe `iio: afe: rescale: Fix boolean logic bug` if you're resending,
otherwise,

Reviewed-by: Liam Beguin <liambeguin@gmail.com>

Thanks,
Liam

> Cc: Liam Beguin <liambeguin@gmail.com>
> Cc: stable@vger.kernel.org
> Fixes: 53ebee949980 ("iio: afe: iio-rescale: Support processed channels")
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
>  drivers/iio/afe/iio-rescale.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
> index 7e511293d6d1..dc426e1484f0 100644
> --- a/drivers/iio/afe/iio-rescale.c
> +++ b/drivers/iio/afe/iio-rescale.c
> @@ -278,7 +278,7 @@ static int rescale_configure_channel(struct device *dev,
>  	chan->ext_info = rescale->ext_info;
>  	chan->type = rescale->cfg->type;
>  
> -	if (iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) ||
> +	if (iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) &&
>  	    iio_channel_has_info(schan, IIO_CHAN_INFO_SCALE)) {
>  		dev_info(dev, "using raw+scale source channel\n");
>  	} else if (iio_channel_has_info(schan, IIO_CHAN_INFO_PROCESSED)) {
> -- 
> 2.35.3
>