On Thu, Apr 24, 2014 at 7:47 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> On Wed, Apr 23, 2014 at 5:28 PM, Thierry Reding
> <thierry.reding@xxxxxxxxx> wrote:
>
>> From: Thierry Reding <treding@xxxxxxxxxx>
>>
>> Many bindings use the -gpio suffix in property names. Support this in
>> addition to the -gpios suffix when requesting GPIOs using the new
>> descriptor-based API.
>>
>> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
>
> Are the DT bindings really full of such ambiguity between
> singular and plural? Examples?
>
> What happens in affected drivers today? It just doesn't work?
They mostly seem to use of_get_named_gpio.
>
> Does that mean these bindings are not actively used by any
> drivers yet so we could augment the bindings instead, or are
> they already deployed so we must implement this?
>
> Would like a word from the DT people here...
Interestingly, there is not a single occurrence of '-gpio ' in
powerpc, but a bunch in ARM. In hindsight, we should have perhaps
enforced using -gpios only, but that doesn't really matter now. We
have -gpio in use, so we need to support it. That doesn't necessarily
mean this function has to support it. For example, this function could
a legacy method and some other function should be used instead
(of_get_named_gpio perhaps).
>> drivers/gpio/gpiolib.c | 18 ++++++++++++------
>> 1 file changed, 12 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
>> index 7a0b97076374..b991462c22fb 100644
>> --- a/drivers/gpio/gpiolib.c
>> +++ b/drivers/gpio/gpiolib.c
>> @@ -2594,17 +2594,23 @@ static struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
>> unsigned int idx,
>> enum gpio_lookup_flags *flags)
>> {
>> + static const char *suffixes[] = { "gpios", "gpio" };
>> char prop_name[32]; /* 32 is max size of property name */
>> enum of_gpio_flags of_flags;
>> struct gpio_desc *desc;
>> + unsigned int i;
>>
>> - if (con_id)
>> - snprintf(prop_name, 32, "%s-gpios", con_id);
>> - else
>> - snprintf(prop_name, 32, "gpios");
>> + for (i = 0; i < ARRAY_SIZE(suffixes); i++) {
>> + if (con_id)
>> + snprintf(prop_name, 32, "%s-%s", con_id, suffixes[i]);
>> + else
>> + snprintf(prop_name, 32, "%s", suffixes[i]);
This has the side effect of searching for "gpio" as property name
which I don't think we want to allow. It also allows a DT with either
suffix to work. While I don't necessarily think the kernel's job
should be DT validation, we don't have any other validation today and
I don't see how this change simplifies the code. Between stricter DT
checking (in the kernel) and simpler code, I'd pick the latter.
Rob
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