Messages in this thread |  | | Date | Mon, 2 Dec 2013 13:11:24 +0200 | From | Heikki Krogerus <> | Subject | Re: [PATCH] gpio: better lookup method for platform GPIOs |
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Hi,
On Mon, Dec 02, 2013 at 07:33:35PM +0900, Alex Courbot wrote: > On 11/29/2013 08:57 PM, Heikki Krogerus wrote: > >Hi, > > > >On Thu, Nov 28, 2013 at 05:46:28PM +0900, Alexandre Courbot wrote: > >>@@ -88,16 +89,20 @@ Note that GPIO_LOOKUP() is just a shortcut to GPIO_LOOKUP_IDX() where idx = 0. > >> > >> A lookup table can then be defined as follows: > >> > >>- struct gpiod_lookup gpios_table[] = { > >>- GPIO_LOOKUP_IDX("gpio.0", 15, "foo.0", "led", 0, GPIO_ACTIVE_HIGH), > >>- GPIO_LOOKUP_IDX("gpio.0", 16, "foo.0", "led", 1, GPIO_ACTIVE_HIGH), > >>- GPIO_LOOKUP_IDX("gpio.0", 17, "foo.0", "led", 2, GPIO_ACTIVE_HIGH), > >>- GPIO_LOOKUP("gpio.0", 1, "foo.0", "power", GPIO_ACTIVE_LOW), > >>- }; > >>+struct gpiod_lookup_table gpios_table = { > >>+ .dev_id = "foo.0", > >>+ .size = 4, > >>+ .table = { > >>+ GPIO_LOOKUP_IDX("gpio.0", 15, "led", 0, GPIO_ACTIVE_HIGH), > >>+ GPIO_LOOKUP_IDX("gpio.0", 16, "led", 1, GPIO_ACTIVE_HIGH), > >>+ GPIO_LOOKUP_IDX("gpio.0", 17, "led", 2, GPIO_ACTIVE_HIGH), > >>+ GPIO_LOOKUP("gpio.0", 1, "power", GPIO_ACTIVE_LOW), > >>+ }, > >>+}; > > > >Instead of using the size variable, wouldn't it be more clear to > >expect the array to be null terminated? > > This is a zero-length array, its entries are not pointers but > flattened lookup entries. Thus you cannot simply null-terminate it. > It would be possible to use { NULL } as a terminator, but this would > expand into a whole gpiod_lookup and is not very pleasant > esthetically-speaking. So I think the size member is maybe better > suited here.
The gpio_loopup_table would look like this, which IMO is more nicer looking compared to the extra size variable:
struct gpiod_lookup_table gpios_table = { .dev_id = "foo.0", .table = { GPIO_LOOKUP_IDX("gpio.0", 15, "led", 0, GPIO_ACTIVE_HIGH), GPIO_LOOKUP_IDX("gpio.0", 16, "led", 1, GPIO_ACTIVE_HIGH), GPIO_LOOKUP_IDX("gpio.0", 17, "led", 2, GPIO_ACTIVE_HIGH), GPIO_LOOKUP("gpio.0", 1, "power", GPIO_ACTIVE_LOW), { }, }, };
That would also make it more straight forward to handle in gbiolib.c:
struct gpiod_lookup *p; ... for (p = table->table; p->chip_label; p++) { ...
Thanks,
-- heikki
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