On Thu, Jun 1, 2017 at 12:19 AM, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote:
> On Tue, May 30, 2017 at 07:52:26AM -0700, Andrey Smirnov wrote:
>> So far this particular aspect of various DT-bindings has been handled
>> on a per-driver basis. With this change, hopefully, we'll have a
>> single place to handle necessary logic inversions and eventually
>> would be able to migrate existing users as well as avoiding adding
>> redundant code to new drivers.
>>
>> Cc: cphealy@xxxxxxxxx
>> Cc: Nikita Yushchenko <nikita.yoush@xxxxxxxxxxxxxxxxxx>
>> Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
>> ---
>> drivers/gpio/gpiolib.c | 42 ++++++++++++++++++++++++++++++++++++++++--
>> include/gpio.h | 20 ++++++++++++++++++++
>> 2 files changed, 60 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
>> index 1f57c76..36d8874 100644
>> --- a/drivers/gpio/gpiolib.c
>> +++ b/drivers/gpio/gpiolib.c
>> @@ -13,6 +13,7 @@ static LIST_HEAD(chip_list);
>> struct gpio_info {
>> struct gpio_chip *chip;
>> bool requested;
>> + bool active_low;
>> char *label;
>> };
>>
>> @@ -45,6 +46,15 @@ static struct gpio_info *gpio_to_desc(unsigned gpio)
>> return NULL;
>> }
>>
>> +static int gpio_adjust_value(struct gpio_info *gi,
>> + int value)
>> +{
>> + if (value < 0)
>> + return value;
>> +
>> + return !!value ^ gi->active_low;
>> +}
>> +
>> int gpio_request(unsigned gpio, const char *label)
>> {
>> struct gpio_info *gi = gpio_to_desc(gpio);
>> @@ -69,6 +79,7 @@ int gpio_request(unsigned gpio, const char *label)
>> }
>>
>> gi->requested = true;
>> + gi->active_low = false;
>> gi->label = xstrdup(label);
>>
>> done:
>> @@ -93,6 +104,7 @@ void gpio_free(unsigned gpio)
>> gi->chip->ops->free(gi->chip, gpio - gi->chip->base);
>>
>> gi->requested = false;
>> + gi->active_low = false;
>> free(gi->label);
>> gi->label = NULL;
>> }
>> @@ -111,10 +123,15 @@ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
>> if (err)
>> return err;
>>
>> + if (flags & GPIOF_ACTIVE_LOW) {
>> + struct gpio_info *gi = gpio_to_desc(gpio);
>> + gi->active_low = true;
>> + }
>> +
>> if (flags & GPIOF_DIR_IN)
>> err = gpio_direction_input(gpio);
>> else
>> - err = gpio_direction_output(gpio,
>> + err = gpio_direction_active(gpio,
>> (flags & GPIOF_INIT_HIGH) ? 1 : 0);
>
> And here things get messy.
>
> For me 'high' and 'low' represent the physical values of a GPIO whereas
> "active" and "inactive" represent the logical values of a GPIO. The flag
> is named GPIOF_INIT_*HIGH*, not GPIOF_INIT_*ACTIVE*, which means a GPIO
> with this flag should get the physical 'high' value, not the logical
> 'active' value.
>
> They goofed the binding in the kernel, so I'm afraid there's nothing we
> can do about this :(
So do we want to:
a) Keep things as is in v2(I am assuming that is not really an option)
b) Improve the optics by introducing GPIOF_INIT_ACTIVE, but keeping
the behavior of hog nodes consistent with Linux kernel
c) Drop this particular chunk of code, not support keep using
gpio_direciton_output(), and print a warning when we encounter a hog
with 'active low' set
d) Drop active low API patch and handle that aspect inside of code of
the driver that needs it
e) Something else
?
Thanks,
Andrey Smirnov
_______________________________________________
barebox mailing list
barebox@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/barebox
