Messages in this thread | | | From | David Brownell <> | Subject | Re: [patch/rfc 2/4] pcf875x I2C GPIO expander driver | Date | Fri, 4 Apr 2008 19:53:53 -0700 |
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On Friday 04 April 2008, Jean Delvare wrote: > > +static ssize_t gpio_direction_store(struct device *dev, > > + struct device_attribute *attr, const char *buf, size_t size) > > +{ > > + const struct gpio_desc *gdesc = dev_get_drvdata(dev); > > + int d, n = gdesc - gpio_desc; > > + > > + if (size >= 3 && !strncmp(buf, "out", 3)) { > > + d = 1; > > + } else if (size >= 2 && !strncmp(buf, "in", 2)) { > > + d = 0; > > As far as I know, the string you receive from sysfs is guaranteed to be > NUL-terminated, so the size checks are not needed. > > > + } else { > > + d = simple_strtoul(buf, NULL, 0); > > This exposes to user-space the so far internal-only decision to encode > output as 1 and input as 0. I don't see much benefit in doing this, in > particular when you don't check for errors so for example an input of > "Out" would result in value 0 i.e. input mode. I'd rather support only > "in" and "out" as valid values and return -EINVAL otherwise.
So, after trimming trailing whitespace:
if (strcmp(buf, "out") == 0) gpio_direction_output(...) else if (strcmp(buf, "in") == 0) gpio_direction_input(...)
Yes, that'd be a lot better.
> > > + } > > + > > + if (d) > > + gpio_direction_output(n, 0); > > + else > > + gpio_direction_input(n); > > + > > + return size; > > +}
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