Hi,

On Fri, Nov 28, 2014 at 04:30:01PM +0900, Alexandre Courbot wrote:

quoted

+/**
+ * do_gpio_hog - Given node is a GPIO hog configuration, handle it
+ * @np:                device node to get GPIO from
+ *
+ * This is only used by of_gpiochip_add to request/set GPIO initial
+ * configuration.
+ */
+static int do_gpio_hog(struct device_node *np)
+{
+       struct gpio_desc *desc = NULL;
+       int err;
+       const char *name;
+       enum gpio_lookup_flags lflags;
+       enum gpiod_flags dflags;
+
+       desc = of_get_gpio_hog(np, &name, &lflags, &dflags);
+       if (!desc)
+               return -ENOTSUPP;
+       else if (IS_ERR(desc))
+               return PTR_ERR(desc);
+
+       err = gpiod_request(desc, name);

Using this function means that a GPIO chip module cannot be unloaded
if it uses GPIO hogs. Is it the intended behavior? If not, please use
gpiochip_request_own_desc() instead, and make sure to call
gpiochip_free_own_desc() for each hog when the driver is unloaded.

The only thing I'd like to have would be that the request here would
be non-exclusive, so that a later driver would still be allowed later
on to request that GPIO later on and manage it itself (ideally using
the usual gpiod_request function).

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com